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WO2018189068A1 - Composition pour la nanoencapsulation et nanocapsules comprenant un milieu à cristaux liquides - Google Patents

Composition pour la nanoencapsulation et nanocapsules comprenant un milieu à cristaux liquides Download PDF

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Publication number
WO2018189068A1
WO2018189068A1 PCT/EP2018/058962 EP2018058962W WO2018189068A1 WO 2018189068 A1 WO2018189068 A1 WO 2018189068A1 EP 2018058962 W EP2018058962 W EP 2018058962W WO 2018189068 A1 WO2018189068 A1 WO 2018189068A1
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nanocapsules
phe
cyc
compounds
mixture
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PCT/EP2018/058962
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English (en)
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Kevin Adlem
Rachel TUFFIN
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Merck Patent Gmbh
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Publication of WO2018189068A1 publication Critical patent/WO2018189068A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/52—Liquid crystal materials characterised by components which are not liquid crystals, e.g. additives with special physical aspect: solvents, solid particles
    • C09K19/54—Additives having no specific mesophase characterised by their chemical composition
    • C09K19/542—Macromolecular compounds
    • C09K19/544—Macromolecular compounds as dispersing or encapsulating medium around the liquid crystal
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/52—Liquid crystal materials characterised by components which are not liquid crystals, e.g. additives with special physical aspect: solvents, solid particles
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/52—Liquid crystal materials characterised by components which are not liquid crystals, e.g. additives with special physical aspect: solvents, solid particles
    • C09K19/54—Additives having no specific mesophase characterised by their chemical composition
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K2019/0444—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit characterized by a linking chain between rings or ring systems, a bridging chain between extensive mesogenic moieties or an end chain group
    • C09K2019/0448—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit characterized by a linking chain between rings or ring systems, a bridging chain between extensive mesogenic moieties or an end chain group the end chain group being a polymerizable end group, e.g. -Sp-P or acrylate
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K19/06—Non-steroidal liquid crystal compounds
    • C09K19/08—Non-steroidal liquid crystal compounds containing at least two non-condensed rings
    • C09K19/10—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings
    • C09K19/12—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings at least two benzene rings directly linked, e.g. biphenyls
    • C09K2019/121—Compounds containing phenylene-1,4-diyl (-Ph-)
    • C09K2019/123—Ph-Ph-Ph
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K19/06—Non-steroidal liquid crystal compounds
    • C09K19/08—Non-steroidal liquid crystal compounds containing at least two non-condensed rings
    • C09K19/10—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings
    • C09K19/14—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings linked by a carbon chain
    • C09K19/18—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings linked by a carbon chain the chain containing carbon-to-carbon triple bonds, e.g. tolans
    • C09K2019/181—Ph-C≡C-Ph
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
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    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K19/06—Non-steroidal liquid crystal compounds
    • C09K19/08—Non-steroidal liquid crystal compounds containing at least two non-condensed rings
    • C09K19/10—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings
    • C09K19/14—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings linked by a carbon chain
    • C09K19/18—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings linked by a carbon chain the chain containing carbon-to-carbon triple bonds, e.g. tolans
    • C09K2019/183—Ph-Ph-C≡C-Ph
    • C—CHEMISTRY; METALLURGY
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    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K19/06—Non-steroidal liquid crystal compounds
    • C09K19/08—Non-steroidal liquid crystal compounds containing at least two non-condensed rings
    • C09K19/30—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing saturated or unsaturated non-aromatic rings, e.g. cyclohexane rings
    • C09K19/3001—Cyclohexane rings
    • C09K19/3003—Compounds containing at least two rings in which the different rings are directly linked (covalent bond)
    • C09K2019/3025—Cy-Ph-Ph-Ph
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    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/52—Liquid crystal materials characterised by components which are not liquid crystals, e.g. additives with special physical aspect: solvents, solid particles
    • C09K2019/525—Solvents
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/52—Liquid crystal materials characterised by components which are not liquid crystals, e.g. additives with special physical aspect: solvents, solid particles
    • C09K2019/528—Surfactants

Definitions

  • composition for nanoencapsulation and nanocapsules comprising a liquid-crystalline medium
  • the present invention relates to compositions for nanoencapsulation which comprise a mesogenic medium as set forth hereinafter, one or more polymerizable compounds, wherein at least one of the one or more polymerizable compounds is a fluorine-containing polymerizable compound, and one or more surfactants, to nanocapsules containing the mesogenic medium, to methods of their preparation and to their use in electro-optical devices.
  • LC media are widely used in liquid crystal displays (LCDs), in particular in electro-optical displays having active-matrix or passive-matrix addressing, to display information.
  • LCDs liquid crystal displays
  • active- matrix displays individual pixels are usually addressed by integrated, nonlinear active elements, such as transistors, for example thin-film transistors (TFTs), while in the case of passive-matrix displays, individual pixels are usually addressed by the multiplex method, as known from the prior art.
  • TFTs thin-film transistors
  • LCDs of the TN (“twisted nematic”) type which however have the disadvantage of a strong viewing-angle dependence of the contrast.
  • so-called VA vertical aligned
  • OCB optical compensated bend
  • PDLC polymer dispersed liquid crystal
  • PIPS polymerization- induced phase separation
  • PDLC films may be prepared based on
  • TIPS temperature-induced phase separation
  • SIPS solvent-induced phase separation
  • PNLC polymer network liquid crystal
  • micrometer-sized encapsulated LC materials Furthermore, micrometer-sized encapsulated LC materials
  • microcapsules for use in displays have been described, wherein the microcapsules are prepared by forming an aqueous emulsion of LC material with an immiscible binder such as polyvinyl alcohol (PVA) which serves as the encapsulating medium, see e.g. US 4,435,047.
  • PVA polyvinyl alcohol
  • LCDs which include a layer comprising nanocapsules, wherein the nanocapsules contain liquid crystal molecules.
  • a configuration of an LCD device arranged with a layer which contains such nanocapsules in a so- called buffer material is described in US 2014/0184984 A1 .
  • Nanocapsules having a mean diameter of approximately 1 10 nm are prepared by adding a nematic LC to a mixture of nonionic polymeric surfactant and PVA, which serves as shell- forming polymer and water-soluble emulsifier, dissolved in aqueous solution, forming a nanoemulsion, heating up of the nanoemulsion to a cloud point and stirring to phase separate PVA around the LC
  • porous nanoparticles made of crosslinked polymer which can act like a sponge to imbibe LC substances, having a possible application as phase retardation films in an LCD.
  • An object of the present invention is therefore to provide improved compositions which allow favourable performance during encapsulation, while further providing favourable characteristics in the resultant nanocapsules, as well as to provide improved nanocapsules comprising mesogenic media. It is a further object to provide an improved method for preparing nanocapsules comprising mesogenic media. In particular, it is an object to provide the compositions and the nanocapsules such that the mesogenic media contained in the nanocapsules have suitably high ⁇ and high electrical resistance as well as suitably high ⁇ and favourable values of the electro-optical parameters, while furthermore particularly providing relatively low rotational viscosity and favourable reliability.
  • the mesogenic media comprised in the nanocapsules exhibit broad and stable LC, in particular nematic, phase ranges, low melting points and a relatively high clearing point, and a suitably high voltage holding ratio. It is a further object to provide stable and reliable nanocapsules and composite systems comprising the nanocapsules and binder which are useful in light-modulation elements and electro-optical devices, in particular having a suitably low threshold voltage, favourably fast response times, improved low-temperature behaviour and an improvement in the operating properties at low temperatures, a minimal temperature dependence of the electro-optical parameters such as, for example, the threshold voltage, and a high contrast.
  • a first aspect of the present invention provides a composition for nanoencapsulation, wherein the composition comprises (i) a mesogenic medium which comprises one or more compounds of formula I
  • R and R' denote, independently of one another, a group selected from F, CF3, OCF3, CN, and straight-chain or branched alkyl or alkoxy having 1 to 15 carbon atoms or straight- chain or branched alkenyl having 2 to 15 carbon atoms which is unsubstituted, monosubstituted by CN or CF3 or mono- or polysubstituted by halogen, preferably F, and wherein one or more CH2 groups may be, in each case independently of one another, replaced by -O-,
  • a and A' denote, independently of one another, a group selected from -Cyc-, -Phe-, -Cyc-Cyc-, -Cyc-Phe-, -Phe-Phe-, -Cyc-Cyc-Cyc-, -Cyc-Cyc-Phe-, -Cyc-Phe-Cyc-, -Cyc-Phe-Cyc-, -Cyc-Phe-Phe-, -Phe-Cyc-Phe-, -Phe-Cyc-Phe- and the respective mirror images thereof,
  • Cyc is trans-1 ,4-cyclohexylene, in which one or two non-adjacent CH2 groups may be replaced by O, and wherein Phe is 1 ,4-phenylene, in which one or two non-adjacent CH groups may be replaced by N and which may be substituted by one or two F, and
  • Y denotes single bond, -COO-, -CH2CH2-, -CF2CF2-,
  • compositions according to the invention which comprise a combination of the components (i), (ii) and (iii) as set forth above it is possible to prepare nanocapsules containing a mesogenic medium in an improved and surprisingly facile process, wherein the compositions exhibit a favourable performance in the process.
  • these compositions allow to obtain nanocapsules which provide significant benefits in terms of their physical and chemical attributes, in particular with respect to their electro-optical properties and their suitability in light-modulation elements and electro-optical devices.
  • polymerizable compound in the composition can contribute to favourably tuning or adjusting the properties of the obtained nanocapsules.
  • the fluorinated reactive monomer compound(s) can be especially useful to adjust, in particular to lower, the surface energy of the obtained polymer, which can favourably improve the material properties and performance, e.g. reduce the operating voltage and improve the switching speed and behaviour.
  • Providing the fluorine-containing polymerizable compound(s) in the composition according to the invention can also be useful to adjust the solubilities and miscibilities of the reactive and non-reactive components of the composition and to favourably influence the performance in the preparation process of the nanocapusles, e.g. in terms of the obtainable phase separation behaviour.
  • nanocapsules which respectively comprise a polymeric shell, and a core containing a mesogenic medium which comprises one or more compounds of formula I as set forth above.
  • nanocapsules according to the invention can be obtained by or
  • a light modulating material which comprises nano-sized droplets (nanodroplets) of LC as a core encapsulated by a polymeric shell can be provided, wherein the nanocapsules as a whole and also the mesogenic medium contained therein have suitable and even improved properties.
  • the LC material nanoencapsulated by a polymeric shell can be easily applied to and supported from a single substrate, which may be flexible and wherein the layer or film thickness can be variable or respectively varied.
  • the LC medium which is surrounded, i.e. enclosed by a polymeric wall is operable in at least two states.
  • the nanodroplets each provide only a comparatively small volume of LC. It was thus presently realized to preferably and favourably provide the LC component having a suitably large ⁇ , while furthermore exhibiting good transmission and good reliability, including in particular a suitable voltage holding ratio (VHR) and thermal and UV stability as well as relatively small rotational viscosity. Furthermore, the LC component can favourably be provided with suitable and reasonably high values for the dielectric anisotropy ⁇ to obtain relatively small threshold voltages in electro-optical device applications.
  • VHR voltage holding ratio
  • the LC component can favourably be provided with suitable and reasonably high values for the dielectric anisotropy ⁇ to obtain relatively small threshold voltages in electro-optical device applications.
  • the interface area between the LC core and the polymeric shell is relatively large compared to the provided nanovolume and that therefore the respective properties of the polymeric shell component and the LC core component and their interrelations need to be particularly taken into consideration.
  • the interactions between the polymer and the LC component can favourably and suitably be set and adjusted, which is primarily obtainable on account of the provided composition for nanoencapsulation according to the invention as well as the control and adaptability of the provided process of preparation.
  • the interface interactions can favour or discourage the formation of any alignment or orientation in the LC nanodroplets.
  • the capsules may advantageously be only very weak scatterers of visible light.
  • the LC medium may in one case form a disordered phase with little or no orientation in the nanosized volumes, in particular an isotropic phase, which can for example provide excellent viewing angle behaviour.
  • an isotropic phase in the unpowered or non-addressed state can be advantageous in device applications in that a very good dark state may be realized, in particular when using polarizers.
  • arrangement may occur, wherein in particular the interface interaction(s) can be used to induce or influence alignment and orientation in the LC medium, for example by setting or adjusting anchoring strengths with the capsule wall.
  • uniform, planar, radial or bipolar alignment may occur.
  • nanocapsules having respectively and individually LC orientation or alignment are randomly dispersed, overall an optical isotropy may be observed.
  • the spherical or spheroidal geometry along with curvature set a constraint or boundary condition for the nematic configuration as well as the alignment of the liquid crystal molecules, which can further depend on the anchoring of the LC at the capsule surface, the elastic properties and the bulk and surface energetics as well as the size of the capsules.
  • the electro-optical response in turn is dependent on the LC ordering and orientation in the nanocapsules. Furthermore, any possible absence or presence of alignment and orientation of the encapsulated LC medium is independent of the substrate such that there is no need to provide an alignment layer on the substrate.
  • the nanocapsules are substantially optically isotropic. This allows to realize an excellent dark state when two crossed polarizers are used. Upon switching with an electric field, in particular in-plane switching, an axial configuration which is optically anisotropic can be obtained, where the induced birefringence causes transmission of light.
  • agitating preferably mechanically agitating, the provided aqueous mixture to obtain nanodroplets comprising the composition, and in particular the mesogenic medium, according to the invention dispersed in an aqueous phase, and subsequent to step (b) polymerizing the one or more polymerizable compounds according to the invention to obtain nanocapsules each comprising a polymeric shell and a core which contains the mesogenic medium as set forth above and below.
  • the aqueous phase can be depleted, removed or exchanged, wherein for example a centrifugation or filtration method can be used.
  • nanocapsules comprising LC medium can be favourably prepared by a process using in situ polymerization, and which in particular is based on polymerization induced phase separation.
  • encapsulation of the mesogenic medium on the nanoscale can favourably be performed starting in situ from polymer precursors.
  • a preformed polymer, and also an emulsifier specifically provided therewith can favourably be avoided.
  • the use of a premade polymer as given may make formation and stabilization of a nanoemulsion difficult while it furthermore may limit the adjustability of the overall process.
  • the polymerizable compound(s) is (are) at least partially soluble or respectively at least partially solubilized in the phase comprising the mesogenic medium, preferably the one or more polymerizable compounds and the mesogenic medium are intimately mixed, in particular homogeneously mixed, wherein this mixture is in a later stage nanophase-separated through PIPS, i.e. polymerization- induced phase separation.
  • the temperature can be set and adjusted to favourably influence the solubility.
  • solubilization and/or mixing optionally and preferably an organic solvent may be added to the composition, which can furthermore favourably influence phase separation during polymerization.
  • the organic solvent may also influence the properties of the obtainable nanocapsules, e.g. by interacting with the LC phase or at the interface between the LC molecules and the polymer wall.
  • the choice of wavelength is favourably not limited by the UV cutoff of glass, but can be rather set e.g. in view of the material properties and stability of the composition. It is also possible to use light including both the UV and the visible spectrum, e.g. by using a lamp in the wavelength range from 300 nm to 600 nm
  • the present process is based on a combination of nanodispersion and PIPS, and it provides significant advantages in terms of providing a controlled and adaptable preparation method.
  • the nanocapsules obtained by or respectively obtainable from this process show suitable and tunable particle size, while at the same time giving favourably high particle size uniformity, i.e. favourably low polydispersity, and in turn advantageously homogeneous product properties. It was surprisingly found that the setting of a suitable capsule nanosize while furthermore observing and achieving a low polydispersity can have a favourable influence on the operating voltage. Considering the controllability and adaptability of the process, the electro-optical parameters of the obtained nanocapsules and in particular of the LC medium contained therein can be favourably set and tuned.
  • the provision of at least one fluorine- containing polymerizable compound in the composition can contribute to favourably tuning or adjusting the properties of the obtained nanocapsules as well as the efficiency and effectiveness of the process for preparing the nanocapsules.
  • fluorinated or at least partially fluorinated polymer shells are formed.
  • the encapsulation process is based on polymerization reaction, i.e. that a specific dynamic process is underlying the capsule formation.
  • the polymerizable compound(s) used for the encapsulation has (have) a suitable miscibility with the LC medium, while the formed capsule shell polymer exhibits a suitably low solubility with the LC material.
  • polymerization conversion or completion can be surprisingly high and the amount of residual unreacted polymerizable compound favourably low. This can ensure that the properties and performance of the LC medium in the formed capsules are not or only minimally affected by residual reactive monomers. It was furthermore found that before polymerization the provision of surfactant can favourably promote formation and subsequently
  • stabilization in particular ionic and/or steric stabilization, of discrete nanodroplets in the dispersion medium, in particular the aqueous dispersion medium, wherein the nanodroplets comprise the LC medium and the polymerizable compound(s).
  • Mechanical agitation in particular high-shear mixing, can suitably yield or further effect dispersion, in particular emulsion, and homogenization, and likewise promote
  • nanodroplet formation Both mechanical agitation and the provision of surfactant thus can play advantageous roles in obtaining nanodroplets and in turn nano-sized capsules, in particular nanocapsules with a substantially uniform size distribution or respectively low polydispersity.
  • the small and uniform size of the nanocapsules can be beneficial in terms of obtaining fast and uniform switching in response to an applied electric field, preferably giving low millisecond or even sub-millisecond response times.
  • phase separation and the properties of the formed polymeric shell, in particular stability and immiscibility with LC component can be advantageously influenced by optionally and preferably crosslinking the forming or respectively formed polymer chains. However, also without such crosslinking the capsule properties can already be sufficiently good.
  • Another aspect of the invention relates to a composite system which comprises the nanocapsules according to the invention and one or more binders. It was found that the combination of the nanocapsules with binder material(s) can suitably influence and increase the processibility and applicability of the light modulating material, in particular in view of coating or printing on substrates and film formation.
  • the one or more binders can act as both dispersant and adhesion or binding agent, and furthermore provide suitable physical and mechanical stability while maintaining or even promoting flexibility. Furthermore, density or concentration of the capsules can advantageously be adjusted by varying the amount of binder provided.
  • a further aspect of the invention provides an electro-optical device which comprises the nanocapsules according to the invention or the composite system according to the invention.
  • the nanoencapsulated LC medium according to the invention optionally combined with a binder material, in an electro-optical device several significant advantages are obtainable. These include, for example, good mechanical stability, flexibility and insensitivity to external applied forces or respectively pressure such as from touch as well as further favourable properties regarding switching speed, transmittance, dark state, viewing angle behaviour and threshold voltage. Further advantages rest in the possible use of flexible substrates and the possibility to vary film or layer thickness and the tolerability of film thickness deviations or variance. In this respect simple dropping, coating or printing methods can be used to apply the light-modulating material to the substrate.
  • an alignment layer such as conventionally used polyimide (PI) alignment layers
  • PI polyimide
  • the two electrodes in the device are provided on the same substrate such as in the case of IPS or FFS a single substrate can be sufficient to provide functionality and stability or respectively support, making the provision of an opposing substrate merely optional.
  • opposing substrate may still be beneficial, for example in terms of providing further optical elements or physical or chemical protection.
  • liquid crystal LC
  • thermotropic LCs thermotropic LCs
  • lyotropic LCs concentration ranges in solutions
  • mesogenic compound and “liquid crystal compound” mean a compound comprising one or more calamitic (rod- or board/lath-shaped) or discotic (disc-shaped) mesogenic groups, i.e. groups with the ability to induce liquid-crystalline phase or mesophase behaviour.
  • the LC compounds or materials and the mesogenic compounds or materials comprising mesogenic groups do not necessarily have to exhibit a liquid-crystalline phase themselves. It is also possible that they show liquid-crystalline phase behaviour only in mixtures with other compounds. This includes low-molecular-weight non-reactive liquid-crystalline compounds, reactive or polymerizable liquid-crystalline compounds, and liquid-crystalline polymers.
  • a calamitic mesogenic compound is usually comprising a mesogenic core consisting of one or more aromatic or non-aromatic cyclic groups connected to each other directly or via linkage groups, optionally comprising terminal groups attached to the ends of the mesogenic core, and optionally comprising one or more lateral groups attached to the long side of the mesogenic core, wherein these terminal and lateral groups are usually selected e.g. from carbyl or hydrocarbyl groups, polar groups like halogen, nitro, hydroxy, etc., or polymerizable groups.
  • liquid crystal material or medium is used for both liquid crystal materials or media and mesogenic materials or media, and vice versa, and the term “mesogen” is used for the mesogenic groups of the material.
  • non-mesogenic compound or material means a compound or material that does not contain a mesogenic group as defined above.
  • polymer will be understood to mean a molecule that encompasses a backbone of one or more distinct types of repeating units (the smallest constitutional unit of the molecule) and is inclusive of the commonly known terms “oligomer”, “copolymer”, “homopolymer” and the like. Further, it will be understood that the term polymer is inclusive of, in addition to the polymer itself, residues from initiators, catalysts, and other elements attendant to the synthesis of such a polymer, where such residues are understood as not being covalently incorporated thereto.
  • residues and other elements while normally removed during post-polymerization purification processes, are typically mixed or co- mingled with the polymer such that they generally remain with the polymer when it is transferred between vessels or between solvents or dispersion media.
  • (meth)acrylic polymer as used in the present invention includes a polymer obtained from acrylic monomers, a polymer obtainable from methacrylic monomers, and a corresponding co-polymer obtainable from mixtures of such monomers.
  • polymerization means the chemical process to form a polymer by bonding together multiple polymerizable groups or polymer precursors (polymerizable compounds) containing such polymerizable groups.
  • Polymerizable compounds with one polymerizable group are also referred to as “monoreactive” compounds, compounds with two polymerizable groups as “direactive” compounds, and compounds with more than two polymerizable groups as “multireactive” compounds.
  • Compounds without a polymerizable group are also referred to as “non-reactive” or “non- polymerizable” compounds.
  • film and layer include rigid or flexible, self-supporting or freestanding films or layers with more or less pronounced mechanical stability, as well as coatings or layers on a supporting substrate or between two substrates.
  • Visible light is electromagnetic radiation that has a wavelength in a range from about 400 nm to about 745 nm.
  • Ultraviolet (UV) light is
  • electromagnetic radiation with a wavelength in a range from about 200 nm to about 400 nm.
  • compositions comprise the components (i), (ii) and (iii) as defined above.
  • a mesogenic medium which comprises one or more compounds of the formula I.
  • compositions as provided according to the invention allow to prepare advantageous nanocapsules containing a mesogenic medium in a favourable process, in particular a process using in situ polymerization, especially a process which is based on PIPS, wherein the compositions have a favourable performance in the process. Furthermore, these compositions allow to obtain nanocapsules which provide significant benefits in terms of their physical and chemical attributes, in particular with respect to their electro-optical properties and their suitability in electro-optical devices. The inventive compositions are thus useful in the preparation of nanocapsules.
  • compositions can be provided by suitably mixing or blending the components.
  • composition according to the invention comprises the LC medium in an amount, based on the overall
  • composition from 5% by weight to 95% by weight, more preferably from 15% by weight to 75% by weight, in particular from 25% by weight to 65% by weight.
  • the composition according to the invention further comprises one or more organic solvents.
  • organic solvent can contribute to setting or adapting the components solubilities or respectively miscibilities.
  • the solvent may act as a suitable cosolvent, wherein the solvent power of other organic constituents may be enhanced or influenced.
  • the organic solvent(s) can have a favourable influence during phase separation induced by the
  • the provision of the organic solvent(s) can contribute to obtaining improved separation of LC material and the prepared polymer component, and it may further influence, in particular reduce, the anchoring energy at the interface.
  • organic solvent(s) standard organic solvents can be used.
  • the solvent(s) can be selected, for example, from aliphatic hydrocarbons, halogenated aliphatic hydrocarbons, aromatic
  • hydrocarbons including fluorinated alcohols, glycols or their esters, ethers, esters, lactones, ketones, and the like, more preferably from diols and n-alkanes. It is also possible to use binary, ternary or higher mixtures of the above solvents. In a particular embodiment it is preferred to use a fluorinated organic solvent.
  • the solvent is selected from one or more of cyclohexane, tetradecafluorohexane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, perfluorohexadecane, 1 ,5-dimethyltetralin, 3-phenoxytoluene, heptadecane 2-isopropoxy ethanol, octyldodecanol, perfluorooctanol, pentafluorooctanol, pentadecafluorooctanol, 1 ,2- ethanediol, 1 ,2-propanediol, 1 ,3-butanediol, 1 ,4-butanediol, pentanediol, in particular 1 ,4-pentanediol, phenylcyclohexane,
  • the organic solvent used comprises hexadecane, methyl octanoate, ethyl acetate or 1 ,4-pentanediol, in particular is hexadecane, methyl octanoate, ethyl acetate or 1 ,4-pentanediol.
  • a combination comprising hexadecane and 1 ,4-pentanediol is used.
  • the organic solvent(s), in particular hexadecane, is (are) preferably added in an amount, based on the overall composition, from 0.1 % by weight to 35% by weight, more preferably from 1 % by weight to 25% by weight, in particular from 3% by weight to 17% by weight.
  • the organic solvent can enhance solubility or respectively solubilisation, or dilute other organic components and may contribute to tuning the viscosity.
  • the organic solvent acts as a hydrophobic agent. Its addition to the dispersed phase of the nano- or miniemulsion can influence, in particular increase, the osmotic pressure in the nanodroplets. This can contribute to stabilizing the "oil-in-water" emulsion by suppressing Ostwald ripening.
  • Preferable organic solvents serving as hydrophobic agents have a solubility in water which is lower than the solubility of the liquid crystal in water, while they are soluble in the liquid crystal.
  • one or more polymerizable compounds are provided as the precursors for the polymeric shell or wall containing or respectively surrounding the LC medium. According to the present invention at least one of the one or more polymerizable
  • the material properties and performance of the prepared nanocapsules and also the process for their preparation may be favourably influenced, e.g. by lowering the surface energy of the polymer, by tuning the anchoring energy at the polymer interface or by adjusting the phase separation.
  • the polymerizable compounds as provided in the composition also comprise, in addition to the at least one fluorine- containing polymerizable compound, one, two or more polymerizable compounds which do not contain fluorine.
  • the polymerizable compound(s) is (are) selected exclusively from fluorine- containing polymerizable compounds, i.e. that the composition contains only fluorine-containing polymerizable compound(s) as the polymerizable compound(s).
  • the one or more fluorine-containing polymerizable compounds are reactive monomers or polymer precursors that have at least one polymerizable group and that contain fluorine.
  • the fluorine-containing polymerizable compounds according to the invention comprise fluorinated compounds that are monofluorinated, polyfluorinated and perfluorinated.
  • the polymerizable or reactive group of the at least one fluorine-containing polymerizable compound is preferably selected from a vinyl group, an acrylate group, a methacrylate group, a fluoroacrylate group, an oxetane group or an epoxy group, especially preferably an acrylate group or a methacrylate group.
  • the at least one fluorine-containing polymerizable compound is selected from a fluorine-containing acrylate and a fluorine-containing methacrylate.
  • the at least one fluorine-containing polymerizable compound in particular the fluorine-containing acrylate and the fluorine-containing methacrylate, may be selected from monoreactive monomers and di- or multireactive monomers.
  • the composition according to the invention comprises the at least one fluorine-containing polymerizable compound in an amount, based on the overall composition, from 0.1 % by weight to 60% by weight, more preferably from 0.5% by weight to 35% by weight, in particular from 1 .5% by weight to 15% by weight.
  • fluorine-containing polymerizable compounds are selected from hexafluoroisopropylacrylate, 1 ,1 -dihydroperfluoropropyl acrylate, perfluorodecylacrylate, pentafluoropropylacrylate,
  • perfluorododecanediol diacrylate perfluorododecyl methacrylate, perfluorohexyl acrylate, perfluorohexyl diacrylate, 3-perfluorohexyl-2- hydroxypropyl acrylate, perfluorohexyl methacrylate, perfluoro-9- methyldecyl methacrylate, perfluoro-5-methylhexylmethacrylate and perfluoro-7-methyloctyl acrylate.
  • the polymerizable compounds according to the invention have at least one polymerizable group.
  • the one or more polymerizable compounds which in addition to the at least one fluorine-containing polymerizable compound may also comprise compounds which do not contain fluorine, are chosen such that they have a suitable and sufficient solubility in the LC component or phase.
  • the polymerizable compound(s) can undergo a suitable polymerization with a high conversion rate, leading to a favourably low amount of residual unreacted polymerizable compound after the reaction. This can provide benefits in terms of stability and performance of the LC medium. Furthermore, the polymerizable
  • the polymer forming therefrom is suitably phase-separating or respectively that the polymer formed thereform is phase-separated to constitute the polymeric capsule shell.
  • solubility of the LC component in the shell polymer and swelling or gelling of the formed polymer shell are favourably avoided or respectively minimized, wherein the amount and also the constitution of the LC medium remains substantially constant in the formed capsules.
  • favourably preferential solubility of any LC compound of the LC material in the wall is minimized or avoided.
  • the polymerization or curing time depends, inter alia, on the reactivity and the amount of the polymenzable material, the thickness of the formed capsule shell and, if present, the type and amount of polymerization initiator as well as the reaction temperature and/or the power of the radiation, e.g. of the UV lamp.
  • the polymerization or curing times and conditions may be chosen such as to e.g. obtain a fast process for polymerization, or alternatively to e.g. obtain a slower process wherein however the completeness of conversion and separation of the polymer may be beneficially influenced. It can thus be preferred to have short polymerization and curing times, for example below 5 minutes, while in an alternative embodiment longer polymerization times, such as more than one hour or even at least three hours, can be preferred.
  • non-mesogenic polymenzable compounds i.e.
  • RMs reactive mesogens
  • these compounds contain a mesogenic group and one or more polymerizable groups, i.e. functional groups which are suitable for polymerization.
  • the polymerizabe compound(s) according to the invention comprise(s) only reactive mesogen(s), i.e. all the reactive monomers are mesogens.
  • RMs can be provided in combination with one or more non-mesogenic polymerizable compounds.
  • the RMs can be monoreactive or di- or multireactive. RMs can exhibit favourable solubility or respectively miscibility with the LC medium.
  • polymerizable mesogenic compounds comprise at least one polymerizable group as a terminal group and a mesogenic group as a core group, further preferably comprising a spacer and/or a linking group between the polymerizable group and the mesogenic group.
  • a spacer and/or a linking group between the polymerizable group and the mesogenic group is used.
  • 2-methyl-1 ,4-phenylene-bis[4[3(acryloyloxy)propyloxy]benzoate (RM 257, Merck KGaA) is used.
  • one or more lateral substituents of the mesogenic group may also be polymerizable groups.
  • the use of mesogenic polymerizable compounds is avoided.
  • one or more polymerizable compounds are added to the composition which are selected from vinylchloride, vinylidenechloride, acrylnitriles, methacrylnitriles, acrylamides,
  • methacrylamides methyl-, ethyl-, n- or tert.- butyl-, cyclohexyl-, 2- ethylhexyl-, phenyloxyethyl-, hydroxyethyl-, hydroxypropyl-, 2-5 C- alkoxyethyl-, tetrahydrofurfurylacrylates or methacrylates, vinylacetates, - propionates, -acrylates, -succinates, N-vinylpyrrolidones, N- vinylcarbazoles, styrenes, divinylbenzenes, ethylenediacrylates, 1 ,6- hexanediolacrylates, bisphenol-A-diacrylates and - dimethacrylates, trimethylylpropanediacrylates, trimethylolpropanetriacrylates,
  • hexaacrylates hexaacrylates.
  • thiol-enes are preferred such as, for example, the commercially available product Norland 65 (Norland Products). It is also possible to use silane-based or siloxane-based reactive monomers. It is particularly preferred that fluorinated variants of the above monomers and polymer precursors are used, either alone or in combination with the non- fluorinated reactive compounds.
  • the polymerizable or reactive group is preferably selected from a vinyl group, an acrylate group, a methacrylate group, a fluoroacrylate group, an oxetane group or an epoxy group, especially preferably an acrylate group or a methacrylate group.
  • the fluorinated polymerizable compounds are selected from fluoroacrylates, fluorinated acrylates and fluorinated methacrylates.
  • one or more polymerizable compounds selected from non-fluorinated acrylates, methacrylates and vinyl acetate are contained in the composition, wherein the composition even more preferably further comprises one or more direactive and/or trireactive polymerizable compounds, preferably selected from fluorinated and/or non-fluorinated diacrylates, dimethacrylates, triacrylates and trimethacrylates.
  • the one or more polymerizable compounds (ii) as set forth above comprise polymerizable groups selected from one, two or more acrylate, methacrylate and vinyl acetate groups, wherein the compounds preferably are non-mesogenic compounds.
  • the composition according to the invention comprises one or more monoacrylates, preferably added in an amount, based on the overall composition, from 0.1 % by weight to 75% by weight, more preferably from 0.5% by weight to 50% by weight, in particular from 2.5% by weight to 25% by weight.
  • non-fluorinated monoreactive compounds are selected from methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, t-butyl acrylate, pentyl acrylate, hexyl acrylate, nonyl acrylate, 2-ethyl-hexyl acrylate, 2-hydroxy-ethyl acrylate, 2-hydroxy- butyl acrylate, 2,3-dihydroxypropyl acrylate, 3-tris(trimethylsiloxy)silylpropyl acrylate, stearylacrylate and glycidyl acrylate.
  • vinyl acetate may be added.
  • composition according to the invention comprises, optionally in addition to the above monoacrylates, one or more monomethacrylates, preferably added in an amount, based on the overall composition, from 0.1 % by weight to 75% by weight, more preferably from 0.5% by weight to 50% by weight, in particular from 2.5% by weight to 25% by weight.
  • Particularly preferred non-fluorinated monoreactive compounds are selected from methyl methacrylate, ethyl methacrylate, propyl
  • methacrylate ispropyl methacrylate, butyl methacrylate, t-butyl
  • methacrylate pentyl methacrylate, hexyl methacrylate, nonyl methacrylate, 2-ethyl-hexyl methacrylate, 2-hydroxy-ethyl methacrylate, 2-hydroxy-butyl methacrylate, 2,3-dihydroxypropyl methacrylate,
  • At least one crosslinking agent is added to the composition, i.e. a polymerizable compound containing two or more polymerizable groups.
  • Crosslinking of the polymeric shell in the prepared particle can provide additional benefits, especially with respect to further improve stability and containment, and to tune or respectively reduce susceptibility to swelling, in particular swelling due to solvent.
  • direactive and multireactive compounds can serve to form polymer networks of their own and/or to crosslink polymer chains formed
  • non-fluorinated compounds are selected from ethylene diacrylate, propylene diacrylate, butylene diacrylate, pentylene diacrylate, hexylene diacrylate, glycol diacrylate, glycerol diacrylate, pentaerythritol tetraacrylate, ethylene dimethacrylate, also known as ethyleneglycol dimethacrylate, propylene diamethcrylate, butylene dimethacrylate, pentylene dimethacrylate, hexylene dimethacrylate, tripropylene glycol diacrylate, glycol dimethacrylate, glycerol
  • the composition according to the invention comprises one or more surfactants.
  • the surfactant(s) can be prepared or provided separately in an initial step, and then added to the other components.
  • the surfactant(s) can be prepared or provided as an aqueous mixture or composition, which is then added to the other components comprising the mesogenic medium and the polymerizable compound(s) as set forth above and below.
  • the one or more surfactants are provided as aqueous surfactant(s).
  • the surfactant(s) can be useful in lowering the surface or interfacial tension and in promoting emulsifying and dispersion.
  • surfactants known in the art can be used, including anionic surfactants, for example sulfate, e.g. sodium lauryl sulfate, sulfonate, phosphate and carboxylate surfactants, cationic surfactants, for example secondary or tertiary amine and quaternary ammonium salt surfactants, zwitterionic surfactants, for example betaine, sultaine and phospholipid surfactants, and nonionic surfactants, for example long chain alcohol and phenol, ether, ester or amide nonionic surfactants.
  • fluorinated surfactant or so-called fluorosurfactant is used, in particular perfluorinated alkylated surfactant.
  • nonionic surfactant is used.
  • the use of nonionic surfactant can provide benefits during the process of preparing the nanocapsules, in particular with respect to dispersion formation and stabilization as well as in PIPS. It was
  • Preferable compounds are selected from the group of polyoxyethylene glycol alkyl ether surfactants, polyoxypropylene glycol alkyl ether surfactants, glucoside alkyl ether surfactants, polyoxyethylene glycol octylphenol ether surfactants such as Triton X-100, polyoxyethylene glycol alkylphenol ether surfactants, glycerol alkyl ester surfactants,
  • polyoxyethylene glycol sorbitan alkyl ester surfactants such as
  • polysorbate polysorbate, sorbitan alkyl ester surfactants, cocamide monoethanol- amine, cocamide diethanolamine and dodecyldimethylamine oxide.
  • the used surfactant(s) is (are) selected from polyoxyethylene glycol alkyl ether surfactants, which comprise commercially available Brij ® agents. Particular preference is given to a surfactant which comprises, more preferably consists of, tricosaethylene glycol dodecyl ether.
  • the commercially available Brij ® L23 (Sigma-Aldrich), also referred to as Brij 35 or polyoxyethylene (23) lauryl ether, is used.
  • surfactant is provided in the composition in an amount, based on the overall composition, of less than 25% by weight, more preferably less than 20% by weight, and in particular less than 15% by weight.
  • the surfactant is provided as a prepared aqueous mixture
  • the amount of water is not considered to contribute to the overall composition in terms of weight, i.e. water is excepted in this respect.
  • polymeric surfactants or surface active polymers or block copolymers can be used.
  • polymerizable surfactant i.e. surfactant comprising one or more polymerizable groups, can be used.
  • Such polymerizable surfactant can be used alone, i.e. as the only surfactant provided, or in combination with non-polymerizable surfactant.
  • a polymerizable surfactant is provided in addition and in combination with a non-polymerizable surfactant.
  • This optional provision of polymerizable surfactant can provide the combined benefits of contributing to suitable droplet formation and stabilization as well as to the formation of stable polymeric capsule shells. Therefore, these compounds act at the same time as surfactant and polymerizable compound.
  • polymerizable nonionic surfactants in particular to nonionic surfactants which additionally have one or more acrylate and/or methacrylate groups.
  • This embodiment which includes the use of polymerizable surfactant can have an advantage in that the template properties at the amphiphilic interface may be particularly well preserved during polymerization.
  • the polymerizable surfactant may not only take part in the polymerization reaction, but may be favourably incorporated as a building block into the polymer shell, and more preferably also at the shell surface such that it may advantageously influence the interface interactions.
  • silicone polyether acrylate is used as polymerizable surfactant, more preferably cross-linkable silicone polyether acrylate. It is also possible to add poly(ethylene glycol) methyl ether methacrylate.
  • the composition according to the invention is provided as an aqueous mixture, wherein more preferably the composition comprising the components (i), (ii) and (iii) are dispersed in an aqueous phase.
  • the provided surfactant(s) can favourably contribute to form and stabilize the dispersion, in particular emulsion, and to promote homogenization.
  • water is not considered to contribute to the overall composition in terms of weight, i.e. water is excepted in this respect.
  • water is provided as purified water, in particular deionized water.
  • composition according to the invention is provided as nanodroplets dispersed in an aqueous phase.
  • composition may contain additional compounds such as one or more pleochroic dyes, in particular dichroic dye(s), one or more chiral
  • Pleochroic dyes preferably are dichroic dyes and can be selected from for example azo dyes and thiadiazol dyes.
  • Suitable chiral compounds are for example standard chiral dopants like R- or S-81 1 , R- or S-101 1 , R- or S-201 1 , R- or S-301 1 , R- or S-401 1 , R- or S-501 1 , or CB 15 (all available from Merck KGaA, Darmstadt, Germany), sorbitols as described in WO 98/00428, hydrobenzoins as described in GB 2,328,207, chiral binaphthols as described in WO 02/94805, chiral binaphthol acetals as described in WO 02/34739, chiral TADDOLs as described in WO 02/06265, or chiral compounds having fluorinated linkage groups as described in WO 02/06196 or WO 02/06195.
  • anisotropy the optical anisotropy, the viscosity and/or the temperature dependence of electro-optical parameters of the LC material.
  • the mesogenic medium according to the invention comprises one or more compounds of the formula I as set forth above.
  • the liquid-crystalline medium consists of 2 to 25, preferably 3 to 20 compounds, at least one of which is a compound of formula I.
  • the medium preferably comprises one or more, more preferably two or more, and most preferably three or more compounds of the formula I according to the invention.
  • the medium preferably comprises low molecular weight liquid-crystalline compounds selected from nematic or nematogenic substances, for example from the known classes of the azoxybenzenes, benzylidene-anilines, biphenyls, terphenyls, phenyl or cyclohexyl
  • benzoates phenyl or cyclohexyl esters of cyclohehexanecarboxylic acid, phenyl or cyclohexyl esters of cyclohexylbenzoic acid, phenyl or cyclohexyl esters of cyclohexylcyclohexanecarboxylic acid, cyclohexylphenyl esters of benzoic acid, of cyclohexanecarboxylic acid and of
  • cyclohexylcyclohexanecarboxylic acid phenylcyclohexanes, cyclohexyl- biphenyls, phenylcyclohexylcyclohexanes, cyclohexylcyclohexanes, cyclohexylcyclohexenes, cyclohexylcyclohexylcyclohexenes, 1 ,4-bis- cyclohexylbenzenes, 4,4'-bis-cyclohexylbiphenyls, phenyl- or cyclo- hexylpy midines, phenyl- or cyclohexylpyridines, phenyl- or cyclo- hexylpyridazines, phenyl- or cydohexyldioxanes, phenyl- or cyclo-hexyl-1 ,3- dithianes, 1 ,2-dip
  • the LC host mixture is a nematic LC mixture, which preferably does not have a chiral LC phase.
  • Suitable LC mixtures can have positive dielectric anisotropy. Such mixtures are described, for example, in JP 07-181 439 (A), EP 0 667 555, EP 0 673 986, DE 195 09 410, DE 195 28 106, DE 195 28 107,
  • the LC medium has negative dielectric anisotropy.
  • Such media are described in for example EP 1 378 557 A1 .
  • the one or more compounds of formula I are selected from one or more compounds of the formulae la, lb and lc, wherein
  • R 1 , R 2 , R 3 , R 4 and R 5 denote, independently of one another, straight- chain or branched alkyl or alkoxy having 1 to 15 carbon atoms or straight-chain or branched alkenyl having 2 to 15 carbon atoms which is unsubstituted, monosubstituted by CN or CF3 or mono- or polysubstituted by halogen, preferably F, and wherein one or more CH2 groups may be, in each case independently of one another, replaced by -O-, -S-, -CO-, -COO-, -OCO-, -OCOO- or -C ⁇ C- in such a manner that oxygen atoms are not linked directly to one another,
  • X 1 denotes F, CF 3 , OCF 3 or CN
  • compositions according to the invention as described above are useful in and provide particular advantages in the method to prepare nanocapsules according to the invention. It was surprisingly found that according to the invention an efficient and controlled process can be carried out, ultimately on the nanoscale, to produce nanosized containers, which typically are spherical or spheroidal, enclosing LC material.
  • the process makes use of dispersion, in particular nanoemulsion, which is also called miniemulsion, wherein nanosized phases comprising LC material and reactive, polymerizable compound(s) are dispersed in a suitable dispersion medium.
  • the dispersed phase exhibits poor solubility in the dispersion medium, that means it shows low solubility or is even practically insoluble in the dispersion medium which forms the continuous phase.
  • water, water-based or aqueous solutions or mixtures are used to form the continuous or external phase.
  • each droplet constitutes a separate nanosized reaction volume for the subsequent polymerization.
  • the process conveniently utilizes in situ polymerization.
  • polymerization is combined with phase separation.
  • the size given by the nanodroplets sets the length scale or volume of these transformations or respectively separations leading to polymerization induced nanophase separation.
  • the droplet interface can serve as a template for the
  • the polymer chains or networks forming or starting to form in the nanodroplets may segregate to or be driven to or accumulate at the interface with the aqueous phase, where polymerization may proceed and also terminate to form a closed encapsulation layer.
  • the forming or respectively formed polymeric shell is substantially immiscible in both the aqueous phase as well as the LC medium. Therefore, in an aspect of the invention the polymerization can ensue, be promoted and/or continue at the interface between the aqueous phase and the phase comprising the LC medium. In this respect the interface can act as a diffusion barrier and as a reaction site, possibly also for reactive species in the aqueous phase.
  • the characteristics, in particular the structure and the building blocks of the polymer, of the forming and formed interface of the capsules can influence the material properties, in particular LC alignment, e.g.
  • anchoring energy or strength is reduced to favourably influence electro- optical switching, wherein e.g. the polymer surface morphology and polarity can be suitably set and adjusted.
  • the combined elements of the process can favourably result in the preparation of a large multitude of individual, dispersed or respectively dispersible nanocapsules which each have a polymeric shell and a core comprising LC material.
  • an aqueous mixture is prepared or provided which comprises the composition according to the invention.
  • a surfactant solution or mixture preferably in water, can be prepared and added to the other components of the composition.
  • the provided aqueous mixture is then agitated, in particular mechanically agitated, to obtain nanodroplets comprising the polymerizable
  • Agitation or mixing can be carried out using high-shear mixing.
  • high-performance dispersing devices using the rotor- stator principle can be used, such as commercially available Turrax (IKA).
  • IKA commercially available Turrax
  • high-shear mixing may be replaced by sonication.
  • sonication and high-shear mixing wherein preferably sonication precedes high-shear mixing.
  • the combination of agitation as described above and the provision of surfactant can favourably result in the suitable formation and stabilization of the dispersion, in particular emulsion.
  • a high-pressure homogenizer optionally and preferably used in addition to the above described mixing, can further favourably influence the preparation of the nanodispersion, in particular nanoemulsion, by setting or adjusting and respectively reducing droplet size and by also making the droplet size distribution narrower, i.e. improving uniformity of the particle size. It is particularly preferred when the high-pressure homogenization is repeated, especially for several times such as three, four or five times.
  • a commercially available Microfluidizer Microfluidics
  • Microfluidics Microfluidics
  • the dispersed nanodroplets are then subjected to a polymerization step.
  • the polymerizable compound(s) contained in, or respectively mixed with, the nanodroplets are polymerized.
  • This polymerization leads to PIPS and the formation of the nanocapsules having a core-shell structure as described above and below.
  • the obtained or respectively obtainable nanocapsule are typically spherical, substantially spherical or spheroidal. In this respect some shape asymmetry or small deformation may be beneficial, e.g. in terms of the operating voltage.
  • Polymerization in the emulsion droplets and at each droplet interface can be carried out using conventional methods. The polymerization can be carried out in one or more steps.
  • polymerization of the polymerizable compound(s) in the nanodroplets is preferably achieved by exposure to heat or to actinic radiation, wherein exposure to actinic radiation means irradiation with light, like UV light, visible light or IR light, irradiation with X-rays or gamma rays, or irradiation with high-energy particles, such as ions or electrons.
  • actinic radiation means irradiation with light, like UV light, visible light or IR light, irradiation with X-rays or gamma rays, or irradiation with high-energy particles, such as ions or electrons.
  • free radical polymerization is carried out.
  • Polymerization can be carried out at a suitable temperature.
  • polymerization is performed at a temperature below the clearing point of the mesogenic mixture.
  • polymerization is carried out by heating the emulsion, i.e. by thermal polymerization, for example by thermal polymerization of acrylate and/or methacrylate compound(s).
  • thermal polymerization for example by thermal polymerization of acrylate and/or methacrylate compound(s).
  • thermal polymerization for example by thermal polymerization of acrylate and/or methacrylate compound(s).
  • thermally initiated free radical polymerization of the reactive polymerizable precursors leading to the nanoencapsulation of the LC material is particularly preferred.
  • polymerization is carried out by photoirradiation, i.e. with light, preferably UV light.
  • a source for actinic radiation for example a single UV lamp or a set of UV lamps can be used. When using a high lamp power the curing time can be reduced.
  • a laser like e.g. a UV laser, a visible laser or an IR laser.
  • Suitable and conventionally used thermal initiators or photoinitiators can be added to the composition to facilitate the reaction, for example azo compounds or organic peroxides such as Luperox type initiators.
  • a photoinitiator when polymerizing by means of UV light, a photoinitiator can be used that decomposes under UV irradiation to produce free radicals or ions that start the polymerization reaction.
  • a radical photoinitiator is used for polymerizing acrylate or methacrylate groups.
  • a cationic photoinitiator is used for polymerizing vinyl, epoxide or oxetane groups preferably a cationic photoinitiator is used.
  • a thermal polymerization initiator that decomposes when heated to produce free radicals or ions that start the polymerization.
  • Typical radical photoinitiators are for example the commercially available Irgacure® or Darocure® (Ciba Geigy AG, Basel, Switzerland).
  • a typical cationic photoinitiator is for example UVI 6974 (Union Carbide).
  • nanodroplets but which are water insoluble, or at least substantially water insoluble.
  • azobisisobutyronitrile AIBN
  • AIBN azobisisobutyronitrile
  • water soluble initiators may be provided, such as for example 2,2'-azobis(2-methylpropionamide) dihydrochloride (AIBA).
  • AIBA 2,2'-azobis(2-methylpropionamide) dihydrochloride
  • a non-ionic initiator in particular a non-ionic photoinitiator.
  • the polymerizable material can additionally comprise one or more additives, such as for example catalysts, sensitizers, stabilizers, inhibitors and chain transfer agents.
  • the polymerizable material may also comprise one or more stabilizers or inhibitors to prevent undesired spontaneous polymerization, like for example the commercially available Irganox® (Ciba Geigy AG, Basel, Switzerland).
  • stabilizers or inhibitors like for example the commercially available Irganox® (Ciba Geigy AG, Basel, Switzerland).
  • chain transfer agents By adding one or more chain transfer agents to the polymerizable material the properties of the obtained or respectively obtainable polymer may be modified.
  • chain transfer agents By using chain transfer agents the length of the free polymer chains and/or the length of the polymer chains between two crosslinks in the polymer can be adjusted, wherein typically the polymer chain length in the polymer decreases when the amount of the chain transfer agent is increased.
  • Polymerization is preferably performed under an inert gas atmosphere, for example nitrogen or argon, more preferably in a heated nitrogen atmosphere. But also polymerization in air is possible.
  • an inert gas atmosphere for example nitrogen or argon, more preferably in a heated nitrogen atmosphere. But also polymerization in air is possible.
  • polymerization is carried out in the presence of the organic solvent described above.
  • the use of the organic solvent for example hexadecane, can be favourable in terms of adjusting the solubility of the reactive compound(s) with the LC material and to stabilize the nanodroplets, and it can also be beneficial in influencing phase separation.
  • the amount of organic solvent, if used at all is limited, typically to below 25% by weight, based on the overall composition, more preferably to less than 20% by weight, and in particular to less than 15% by weight.
  • the formed polymer shell suitably exhibits low solubility, i.e. is
  • the forming polymer or respectively the formed polymer in the shell is crosslinked.
  • Such crosslinking can provide benefits in forming a stable polymeric shell and in giving suitable containment and barrier functionality, while maintaining sufficient mechanical flexibility.
  • the process according to the invention thus provides encapsulation and confinement of the mesogenic medium, while maintaining the electro- optical performance and in particular electric responsiveness of the LC material.
  • the composition as well as process conditions are provided such that stability of the LC material is maintained.
  • the LC can therefore exhibit in the formed nanocapsules favourable characteristics, for example suitably high ⁇ , suitably high ⁇ , a high favourable clearing point and a low melting point.
  • the LC material provided can show suitable and favourable stability in the polymerization, for example with respect to exposure to heat or UV light.
  • the provided composition as well as the produced nanocapsules show suitable stability and chemical resistance to the presence of water, for example with respect to hydrolysis.
  • the amount of water may be reduced or even substantially minimized by providing or adding polar media, preferably non-aqueous polar media, containing for example formamide or ethylene glycol. Therefore, in the process stable nanocapsules are produced which are suitably dispersed.
  • the aqueous phase can be removed, or respectively the amount of water can be reduced or depleted, or alternatively the aqueous phase can be exchanged for another dispersion medium.
  • the dispersed or respectively dispersible nanocapsules are substantially or fully separated from the aqueous phase, for example by filtration or centnfugation.
  • Conventionally used filtration e.g. membrane filtration, dialysis, cross-flow filtration and in particular cross-flow filtration in combination with dialysis, and/or centrifugation techniques can be used.
  • Filtration and/or centrifugation can provide further benefits by, for example, removing excess or unwanted or even residual surfactant. It is thus possible to not only provide concentration of the nanocapsules but also purification, e.g. by removing contaminants, impurities or unwanted ions.
  • the amount of surface charge of the capsules is kept at a minimum.
  • the nanocapsules can be subjected to the separation techniques with relative ease. It is also possible to dry the nanocapsules, wherein drying means removing the dispersion medium but leaving the contained LC material inside the capsules. Conventional techniques such as drying in air, critical point drying and freeze-drying, in particular freeze-drying can be used.
  • the process according to the invention provides a large multitute of individual nanocapsules which are dispersible and even redispersible. They can thus be further used and applied to various environments with ease and flexibility. Due to their stability storing of the capsules, in particular with suitably long shelf life, before use in various applications also becomes possible.
  • capsules are suitably stable during processing, in particular for coating applications.
  • the process as described above provides a convenient method to produce the nanocapsules in a controlled and adaptable manner.
  • capsule particle size can suitably be tuned while keeping polydispersity low, for example by adjusting the amount of surfactant in the composition. It was surprisingly found that a suitably set, uniform capsule size can be particularly advantageous in view of reducing the operating voltage in electro-optical applications.
  • the surfactant provided in the composition can be incorporated in the polymeric capsule shell, at least in part, and in particular at the interface with the LC in the interior of the capsule.
  • Such incorporated surfactant molecules at the interface may favourably influence the electro-optical performance and reduce the operating voltage, in particular by setting or tuning the interfacial properties and interactions.
  • the surfactant may favourably influence alignment of the LC molecules, e.g. promoting a homeotropic alignment resulting in a radial configuration. Additionally or alternatively the surfactant molecules may influence the morphology and the
  • the surfactant provided in the composition thus not only contributes to the advantageous process according to the invention, but it may also provide benefits in the obtained nanocapsules.
  • polymerization and/or are added to the obtained nanocapsules.
  • the further additive(s) may be added after carrying out the polymerization and forming the nanocapsules.
  • two or more surfactants are used in the dispersion of the composition as nanodroplets in an aqueous phase.
  • one or more further additives i.e. in addition to the surfactant(s).
  • an agent may be used which influences wettability, solubility, viscosity or the osmotic pressure. In particular hydrophobic or
  • hydrophobizing agents may preferably additionally be added before, during or also after the dispersion of the composition.
  • said nanocapsules constitute nanocontainers having a polymeric shell, which optionally and preferably is crosslinked, filled with the LC material.
  • the capsules are individual and separate, i.e. discrete and dispersible particles having a core-shell structure.
  • the capsules can act individually but also collectively as light modulating material. They can be applied to various environments and, depending on the dispersion medium, be redispersed in different media.
  • nanocapsules can also be referred to as nanoparticles.
  • the nanoparticles comprise nanoscale LC material surrounded by a polymer shell.
  • These nanoencapsulated liquid crystals may optionally additionally be embedded in a polymeric binder.
  • phase separation is less pronounced or less complete it can be possible that a polymer network is forming in the droplet interior such that capsules are obtained that exhibit a sponge-like or porous interior, wherein the LC material fills the voids.
  • the LC material is filling the pores in the sponge-like structure or network, while a shell encloses the LC material.
  • the separation between the LC material and the polymer may be at an intermediate level wherein the interface or boundary between the LC interior and the wall is only less pronounced and shows a gradient behaviour.
  • the comprised mesogenic medium can further contain one or more chiral dopants and/or one or more pleochroic dyes and/or other customary additives.
  • the nanocapsules according to the invention are obtained by or obtainable from polymerization of the inventive composition, and in particular from the efficient and controlled process described herein.
  • a shell polymer in the nanocapsules a shell polymer can be provided, in particular by polymerizing the precursor compound(s) described above, which is well matched with respect to the LC component and which is compatible with the LC performance. It is preferred that the electrical impedance of the capsule polymer is at least equal to and more preferably larger than that of the LC material. According to the invention the obtained shell polymer is fluorinated or at least partially fluorinated, which can provide the additional advantages and benefits as described above.
  • the shell polymer can be advantageous in terms of
  • the capsules according to the invention wherein a liquid crystal is encapsulated by a shell material component, are characterized in that they are nano-sized. Preference is given to nanocapsules having an average size of not greater than 400 nm. Preferably, the nanocapsules have an average size, as determined by dynamic light scattering analysis, of not greater than 400 nm, more preferably of not greater than 250 nm. Dynamic light scattering (DLS) is a commonly known technique which is useful for determining the size as well as the size distribution of particles in the submicron region.
  • DLS Dynamic light scattering
  • the average size of the nanocapsules is below 200 nm, in particular is not greater than 150 nm, as is preferably
  • the average nanocapsule size is below the wavelength of visible light, in particular smaller than ⁇ /4 of visible light. It is advantageously found that the nanocapsules according to the invention in at least one state, in particular with appropriate LC alignment or configuration, can be very weak scatterers of visible light, i.e. that they do not, or substantially not, scatter visible light. In this case the capsules can be useful in modulating the phase shift between the two polarization components of light, i.e. the phase retardation, while not showing or substantially not showing unwanted scattering of light in any state.
  • the polymer-encapsulated mesogenic medium preferably exhibits a confinement size from 15 nm to 400 nm, more preferably from 50 nm to 250 nm and in particular from 75 nm to 150 nm.
  • the functionality of the capsules may become less efficient, considering that the amount of enclosed LC material decreases and also the mobility of the LC molecules becomes more limited.
  • the thickness of the polymeric shell or respectively wall, which forms a discrete individual structure, is chosen such that it effectively contains and stably confines the contained LC medium, while at the same time allowing for relative flexibility and still enabling excellent electric responsiveness of the LC material.
  • the shell should preferably be as thin as possible while still providing adequate strength for containment. Therefore, the typical capsule shell or wall thickness is below 100 nm.
  • the polymeric shell has a thickness of less than 50 nm, more preferably below 25 nm, and in particular below 15 nm. In a preferred embodiment, the polymeric shell has a thickness from 1 nm to 15 nm , more preferably form 3 nm to 10 nm, and in particular from 5 nm to 8 nm.
  • Microscopy techniques in particular SEM and TEM can be used to observe the nanocapsule size, structure and morphology. Wall thickness can e.g. be determined by TEM on freeze-fractured samples. Alternatively, neutron scattering techniques may be used. Moreover, for example AFM, NMR, ellipsometric and sum-frequency generation techniques can be useful to study the nanocapsule structure.
  • the nanocapsules according to the invention typically have spherical or spheroidal shape, wherein the hollow spherical or spheroidal shells are filled with or respectively contain the LC medium according to the invention.
  • nanocapsules are substantially free of surfactant, such that preferably even residual surfactant is kept at a minimum or is even entirely avoided. Therefore, in an aspect nanocapsules are provided which are substantially free of surfactant.
  • the present invention thus provides a plurality of discrete spherical or spheroidal bodies or particles of LC which are each nanoencapsulated by a polymeric shell and which each individually but also collectively are operable in electro-optical devices in at least two states.
  • the LC component provides the beneficial chemical, physical and electro- optical characteristics as described above, such as good reliability and stability and low rotational viscosity.
  • the LC medium according to the invention has a birefringence of ⁇ > 0.15, more preferably > 0.20 and most preferably > 0.25. It is even more preferred when the LC medium according to the invention additionally has a dielectric anisotropy of ⁇ > 10.
  • This uniformity can favourably provide a uniform electro- optical performance of the capsules in device applications.
  • the capsules obtained by or respectively obtainable from the controlled and adaptable process according to the invention can be adjusted and tuned in terms of capsule size, which in turn allows to tune the electro-optical performance as desired, in particular based on the Kerr effect.
  • a composite system which comprises the nanocapsules according to the invention and one or more binders.
  • the discrete nanocapsules can be mixed with a binder material, wherein the mixed nanocapsules substantially maintain, preferably fully maintain, their integrity in the composite while however being bound, held or mounted in the binder.
  • the binder material can be the same material as the polymeric shell material or a different material. Therefore, according to the invention the nanocapsules can be dispersed in a binder made from the same material as or a different material from that of the nanocapsule shell.
  • the binder is a different or at least modified material.
  • the binder can be useful in that it can disperse the nanocapsules, wherein the amount or concentration of the capsules can be set and adjusted. Surprisingly, by independently providing the capsules and a suitable binder the amount of the capsules in the combined composite cannot only be tuned, but especially a very high content, and alternatively also a very low content, of the capsules is obtainable if desired.
  • the nanocapsules are contained in the composite in a proportion from about 2% by weight to about 95% by weight.
  • the composite contains the nanocapsules in a range from 10% by weight to 85% by weight, more preferably from 30% by weight to 70% by weight. In a preferred
  • the amounts of binder and nanocapsules used are approximately the same. In another embodiment the composite contains above 50% by weight of the nanocapsules.
  • the binder material can furthermore improve or influence the coatabilty or printability of the capsules and the film forming ability and performance.
  • the binder can provide mechanical support while maintaining a suitable degree of flexibility, and it can serve as a matrix.
  • the binder furthermore exhibits suitable and adequate transparency.
  • the binder can be selected from, for example, inorganic glass monoliths, as described e.g. in US 4,814,21 1 , or other inorganic materials.
  • the binder is a polymeric material.
  • Suitable materials may be synthetic resins such as, for example, epoxy resins and polyurethanes which, for example, are thermally curable.
  • vinyl compounds and acrylates in particular polyvinyl acrylates and polyvinyl acetates may be used.
  • polymethyl methacrylate, polyurea, polyurethane, urea formaldehyde, melamine formaldehyde, melamine urea formaldehyde can be used or added. It is also possible to use thiol-ene based systems, for example, the commercially available product Norland Optical Adhesive 65 (Norland Products).
  • water-soluble polymers such as, for example, polyvinyl alcohol (PVA), starch, carboxyl methyl cellulose, methyl cellulose, ethyl cellulose, polyvinyl pyrrolidine, gelatin, alginate, casein, gum arabic, or latex-like emulsions.
  • PVA polyvinyl alcohol
  • the binder can for example be chosen in view of setting the respective hydrophobicity or hydrophilicity.
  • the binder, in particular the dried binder absorbs little or no water.
  • the one or more binders comprise polyvinyl alcohol, which includes partially and fully hydrolyzed PVA.
  • water solubility and hydrophilicity can be adjusted by varying the degree of hydrolysis.
  • water uptake may be controlled or reduced.
  • the properties, such as mechanical strength or viscosity, of the PVA may be favourably set by e.g. adjusting the molecular weight, the degree of hydrolysis or by chemical modification of the PVA.
  • the binder properties can also be favourably influenced by cross-linking the binder. Therefore, in particular when PVA is provided as the binder, in an embodiment the binder is cross-linked, preferably by cross-linking agents such as dialdehydes, e.g. glutaraldehyde, formaldehyde and glyoxal. Such cross-linking may e.g. favourably reduce any tendency for undesirable crack-formation.
  • the composite may further comprise customary additives such as stabilizers, antioxidants, free radical scavengers and/or plasticizers.
  • additives such as stabilizers, antioxidants, free radical scavengers and/or plasticizers.
  • ethylene glycol can be used as a preferable plasticizer.
  • glycerol to the binder, in particular PVA-based binder.
  • These additives added to the binder, in particular to PVA may also be useful to favourably influence or adjust further material properties, e.g. the operating voltage or the dielectric permittivity.
  • film-forming agents for example polyacrylic acid, and anti-foaming agents may be added.
  • Such agents may be used to improve film formation and substrate wettability.
  • degassing and/or filtration of the coating may be used to improve film formation and substrate wettability.
  • composition can be carried out to further improve film properties.
  • setting and adjusting binder viscosity can have a favourable influence on the forming or respectively formed film.
  • the binder can be provided as a liquid or paste, wherein a carrier medium or solvent, such as water, aqueous solvent or organic solvent, can be removed from the composite mixture, for example during or after film formation, in particular by evaporation at an elevated temperature.
  • a carrier medium or solvent such as water, aqueous solvent or organic solvent
  • the binder preferably mixes and combines well with the nanocapsules, while further avoiding aggregation of capsules, such that e.g. light leakage can be avoided or minimized, which in turn can make a very good dark state possible.
  • the binder can be chosen such that a high density of nanocapsules can be provided in the composite, for example in a film formed of the composite.
  • the structural and mechanical advantages of the binder can be combined with the favourable electro-optical properties of the LC capsules.
  • the nanocapsules according to the invention can be applied to a large variety of different environments, in particular by (re)dispersing them. They can be favourably dispersed in or respectively mixed with the binder.
  • the binder cannot only improve film forming behviour but also film properties, wherein in particular the binder can hold the capsules relative to a substrate.
  • the capsules are randomly distributed or respectively randomly oriented in the binder.
  • the composite comprising the binder material, but also the nanocapsules on their own, may be suitably applied or laminated to a substrate.
  • the composite or just the nanocapsules can be applied onto the substrate by conventional coating techniques such as spin coating, blade coating or drop coating. Alternatively they can also be applied to the substrate by conventional and known printing methods, like for example ink-jet printing. It is also possible to dissolve the capsules or the composite in a suitable solvent. This solution is then coated or printed onto the substrate, for example by spin-coating or printing or other known techniques, and the solvent is evaporated off. In many cases it is suitable to heat the mixture in order to facilitate the evaporation of the solvent.
  • solvents for example water, aqueous mixtures or standard organic solvents can be used.
  • the material applied to the substrate is the composite, i.e. that it also contains binder.
  • films are formed having a thickness of below 25 ⁇ , preferably below 15 ⁇ .
  • a film made of the composite has a thicknes of from 0.5 ⁇ to 10 ⁇ , very preferably from 1 ⁇ to 7 ⁇ , in particular from 2 ⁇ to 5 ⁇ .
  • substrate for example glass, silicon, quartz sheets or plastic films can be used. It is also possible to put a second substrate on top of the applied, preferably coated or printed, material. Isotropic or birefringent substrates can be used. It is also possible to apply an optical coating, in particular with optical adhesive. In a preferred embodiment the substrate can be a flexible material. Given the flexibility as provided by the composite, overall a flexible system or device is thus obtainable.
  • Suitable and preferred plastic substrates are for example films of polyester such as polyethyleneterephthalate (PET) or polyethylenenaphthalate
  • PET films polyvinylalcohol (PVA), polycarbonate (PC) or triacetylcellulose (TAC), more preferably PET or TAC films.
  • PVA polyvinylalcohol
  • PC polycarbonate
  • TAC triacetylcellulose
  • PET films are commercially available for example from DuPont Teijin Films under the trade name Melinex ® .
  • the substrates can be transparent and transmissive or reflective.
  • the substrates can exhibit electrode(s).
  • a glass substrate with ITO electrodes is provided.
  • the electrical and optical properties of the LC material, the polymeric capsule shell and the binder are favourably and preferably matched or aligned in terms of compatibility and in view of the respective applications.
  • the composite according to the invention can provide suitable and advantageous electro-optical behaviour and performance.
  • the binder and preferably also the polymer shell, has a relatively large impedance in view of the electric responsiveness of the LC as well as a suitable dielectric constant close to that of the LC material to limit charging at the interfaces. It is observed that the dielectric constant of the binder is sufficiently high to ensure that an electric field is efficiently applied across the LC medium in the capsules. Any charge or ionic content in these materials is preferably minimized to keep conductivity very low. In this respect it was found that the properties of the provided binder, preferably PVA, can be improved by purification, in particular by removing or decreasing the amount of impurities and charged
  • the binder in particular PVA, may be dissolved and washed in deionized water or alcohol, and it may be treated by dialysis or soxhlet purification.
  • the refractive indices of the LC material, the polymeric capsule shell and the binder are favourably and preferably matched or aligned in view of optimum performance in the respective applications.
  • the refractive indices of the LC material and the binder are coordinated.
  • the refractive index of the binder can be set or adjusted in view of the extraordinary refractive index (n e ) of the LC, the ordinary refractive index (n 0 ) of the LC, or the average refractive index (n avg ) of the LC.
  • the refractive index of the binder, and also of the shell polymer can be matched closely to n e , n 0 or n avg of the LC material.
  • the nanocapsules are dispersed in the binder, wherein the capsules in the binder exhibit a random orientation relative to each other. Regardless of any possible absence or presence of alignment or orientation of the LC material within each individual capsule, this random orientation of the capsules with respect to each other can result in the LC material as a whole giving an observed average refractive index (n avg ). Considering the nano-size of the capsules and their favourable potential to act as only very weak scatterers of light, in this embodiment the
  • the refractive index of the binder, and preferably also the polymeric capsule shell can e.g. suitably and advantageously be adjusted or matched with respect to n avg of the LC material.
  • nanocapsules can thus behave as efficient nanoscale phase modulators.
  • light scattering may be substantially suppressed, preferably completely suppressed, in particular for sizes smaller than 400 nm.
  • scattering and refraction may be controlled by matching or adjusting the refractive indices of the LC material and of the polymeric material(s).
  • the phase shift can be polarization- independent for normally incident light.
  • the capsules are aligned or oriented in the binder.
  • the composite systems according to the invention advantageously allow for a high degree of adaptability and for setting and adjusting several degrees of freedom, especially in view of tuning the electro-optical properties and functionality.
  • the layer or film thickness can be set, adapted or varied while being able to independently vary the density of the nano-sized LC material in the film, wherein furthermore the size of the nanocapsules, i.e. the amount of LC material in each individual capsule can be preset and thus also adjusted.
  • the LC medium can be chosen to have specific properties, e.g. suitably high values of ⁇ and ⁇ .
  • the amount of LC in the composition, in the nanocapsules and in the composite is suitably maximized to achieve favourably high electro-optical performance.
  • a composite can favourably be provided, with relative production ease and high processibility, that can make good transmittance, low operating voltages, improved VHR and a good dark state possible.
  • a robust, effective and efficient system is obtainable, which is applicable to a single substrate without any alignment layer or without surface rubbing and which can exhibit relative insensitivity to layer thickness deviations or to external forces such as touching, also in terms of light leakage.
  • a wide viewing angle can be obtainable without providing an alignment layer or an additional retardation layer.
  • the nanocapsules and composite systems as provided show sufficient processibility such that aggregation during concentration and filtration of the capsules, mixing with the binder, film formation and optional drying of the film is kept at a minimum.
  • nanocapsules and the composites according to the invention are useful in displays and other optical and electro-optical applications.
  • the nanocapsules containing the LC medium are suitable for efficient control and modulation of light. They may be used, for example, in optical filters, tunable polarizers and lenses, and phase plates. As phase modulators they may be useful for photonic devices, optical communications and information processing, and three-dimensional displays. A further use is in smart windows or privacy windows which are switchable.
  • the invention thus advantageously provides light-modulation elements and electro-optical modulators. These elements and modulators comprise the nanocapsules according to the invention, wherein preferably the capsules are mixed and dispersed in the binder.
  • an electro-optical device in particular an electro-optical display, which makes advantageous use of the
  • nanocapsules and/or the composite system as described above and below In the device a plurality of the nanocapsules are provided.
  • Many of the mesogenic compounds or mixtures thereof described above and below are commercially available. All of these compounds are either known or can be prepared by methods which are known per se, as described in the literature (for example in the standard works such as Houben-Weyl, Methoden der Organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart), to be precise under reaction conditions which are known and suitable for said reactions. Use may also be made here of variants which are known per se, but are not mentioned here in greater detail.
  • the media according to the invention are prepared in a manner conventional per se.
  • the components are dissolved in one another, preferably at elevated temperature.
  • the liquid-crystalline phases of the present invention can be modified in such a way that they can be used in liquid-crystal display elements.
  • Additives of this type are known to the person skilled in the art and are described in detail in the literature (H. Kelker/ R. Hatz, Handbook of Liquid Crystals, Verlag Chemie, Weinheim, 1980).
  • pleochroic dyes can be added for the production of coloured guest-host systems or substances can be added in order to modify the dielectric anisotropy, the viscosity and/or the alignment of the nematic phases.
  • alkyl according to the present invention preferably
  • alkyl groups having 1 -7 carbon atoms encompasses straight-chain and branched alkyl groups having 1 -7 carbon atoms, particularly the straight-chain groups methyl, ethyl, propyl, butyl, pentyl, hexyl and heptyl. Groups having 2-5 carbon atoms are generally preferred.
  • An alkoxy can be straight-chain or branched, and it preferably is straight- chain and has 1 , 2, 3, 4, 5, 6 or 7 carbon atoms, and accordingly is preferably methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy or heptoxy.
  • alkenyl according to the present invention preferably
  • alkenyl groups having 2-7 carbon atoms, in particular the straight-chain groups.
  • Particularly preferred alkenyl groups are C2-C7-I E-alkenyl, C 4 -C7-3E-alkenyl, Cs-C7-4E-alkenyl, C6-C7-5E-alkenyl and C7-6E-alkenyl, in particular C2-C7-I E-alkenyl,
  • alkenyl groups are vinyl, 1 E-propenyl, 1 E-butenyl, 1 E-pentenyl, 1 E-hexenyl, 1 E-heptenyl, 3-butenyl, 3E-pentenyl, 3E-hexenyl, 3E-heptenyl, 4-pentenyl, 4Z-hexenyl, 4E-hexenyl, 4Z-heptenyl, 5-hexenyl and 6-heptenyl. Groups having up to 5 carbon atoms are generally preferred.
  • Fluorinated alkyl or alkoxy preferably comprises CF3, OCF3, CFH2, OCFH2, CF 2 H, OCF2H, C2F5, OC2F5, CFHCFs, CFHCF2H, CFHCFH2, CH2CF3, CH2CF2H, CH2CFH2, CF2CF2H, CF2CFH2, OCFHCF3,
  • Fluoroalkyl in a preferred embodiment encompasses straight-chain groups with terminal fluorine, i.e. fluoromethyl, 2-fluoroethyl, 3-fluoropropyl, 4-fluorobutyl, 5-fluoropentyl,
  • Halogen is preferably F or CI, in particular F.
  • one of the above mentioned groups is an alkyl group in which one Ch group has been replaced by -O- and one has been replaced by -CO-, these are preferably adjacent. These thus contain an acyloxy group -CO-O- or an oxycarbonyl group -O-CO-. These are preferably straight- chain and have 2 to 6 carbon atoms.
  • one of the above mentioned groups is an alkyl or alkenyl group which is monosubstituted by CN or CF3, this group is preferably straight-chain.
  • the substitution by CN or CF3 is in any position.
  • one of the above mentioned groups is an alkyl or alkenyl group which is at least monosubstituted by halogen, this group is preferably straight-chain and halogen is preferably F or CI, more preferably F. In the case of polysubstitution, halogen is preferably F.
  • the resulting groups also include perfluorinated groups.
  • the fluoro or chloro substituent can be in any desired position, but is preferably in the
  • Compounds containing branched groups may occasionally be of importance owing to better solubility in some conventional liquid-crystalline base materials. However, they are particularly suitable as chiral dopants if they are optically active.
  • Branched groups of this type generally contain not more than one chain branch.
  • Preferred branched groups are isopropyl, 2-butyl
  • one of the above mentioned groups is an alkyl group in which two or more Ch groups have been replaced by -O- and/or -CO-O-, this can be straight-chain or branched. It is preferably branched and has 3 to 12 carbon atoms.
  • biscarboxymethyl 2,2-bis- carboxyethyl, 3,3-biscarboxypropyl, 4,4-biscarboxybutyl, 5,5-biscarboxy- pentyl, 6,6-biscarboxyhexyl, 7,7-biscarboxyheptyl, 8,8-biscarboxyoctyl, 9,9-biscarboxynonyl, 10,10-biscarboxydecyl, bis(methoxycarbonyl)methyl, 2,2-bis(methoxycarbonyl)ethyl, 3,3-bis(methoxycarbonyl)propyl, 4,4-bis- (methoxycarbonyl)butyl, 5,5-bis(methoxycarbonyl)pentyl, 6,6-bis(methoxy- carbonyl)hexyl, 7,7-bis(methoxycarbonyl)heptyl, 8,8-bis(methoxycarbonyl)- octyl, bis(e
  • the LC medium according to the present invention preferably has a nematic phase range between -10°C and +70°C.
  • the LC medium even more preferably has a nematic phase range between -20°C and +80°C. It is most preferred when the LC medium according to the present invention has a nematic phase range between -20°C and +90°C.
  • the LC medium according to the present invention preferably has a birefringence of ⁇ > 0.15, more preferably > 0.20, and most preferably > 0.25.
  • the LC medium according to the present invention preferably has a dielectric anisotropy ⁇ > +10, more preferably > +15, and most preferably > +20.
  • the LC medium according to the present invention preferably and favourably exhibits a high reliability and a high electric resistivity, also known as specific resistivity (SR).
  • SR value of an LC medium according to the invention is preferably > 1 x10 13 W cm, very preferably > 1 x10 14 W cm. Unless described otherwise, the measurement of the SR is carried out as described in G. Weber et al., Liquid Crystals 5, 1381 (1989).
  • the LC medium according to the present invention also preferably and favourably exhibits a high voltage holding ratio (VHR), see S. Matsumoto et al., Liquid Crystals 5, 1320 (1989); K. Niwa et al., Proc. SID
  • the VHR of an LC medium according to the invention is preferably > 90 %, very preferably > 95 %. Unless described otherwise, the measurement of the VHR is carried out as described in T. Jacob, U. Finkenzeller in "Merck Liquid Crystals - Physical Properties of Liquid Crystals", 1997.
  • the dielectric anisotropy ⁇ is determined at 20°C and 1 kHz.
  • the optical anisotropy ⁇ is determined at 20°C and a wavelength of 589.3 nm.
  • ⁇ and ⁇ values and the rotational viscosity ( ⁇ ) of the compounds according to the invention are obtained by linear extrapolation from liquid- crystalline mixtures consisting of 5% to 10% of the respective compound according to the invention and 90% to 95% of the commercially available liquid-crystal mixtures ZLI-2857 or ZLI-4792 (both mixtures from Merck KGaA).
  • C crystalline phase
  • N nematic phase
  • Sm nematic phase
  • Table C gives the meanings of the codes for the left- hand or right-hand end groups.
  • the acronyms are composed of the codes for the ring elements with optional linking groups, followed by a first hyphen and the codes for the left-hand end group, and a second hyphen and the codes for the right-hand end group.
  • Table D shows illustrative structures of compounds together with their respective abbreviations.
  • n and m each denote integers, and the three dots are placeholders for other abbreviations from this table.
  • n, m and I preferably, independently of one another, denote 1 to 7.
  • Table E shows possible stabilizers which can be added to the LC media according to the invention, wherein n denotes an integer from 1 to 12, preferably 1 , 2, 3, 4, 5, 6, 7 or 8, terminal methyl groups are not shown.
  • the LC media preferably comprise 0 to 10% by weight, in particular 1 ppm to 5% by weight, particularly preferably 1 ppm to 1 % by weight, of stabilizers.
  • Table F below shows illustrative compounds which can preferably be used as chiral dopants in the mesogenic media according to the present invention.
  • the mesogenic media comprise one or more compounds selected from the compounds shown in Table F.
  • the mesogenic media according to the present invention preferably comprise two or more, preferably four or more, compounds selected from the compounds shown in the above tables D to F.
  • the LC media according to the present invention preferably comprise three or more, more preferably five or more compounds shown in Table D.
  • Vo denotes threshold voltage, capacitive [V] at 20°C, n e denotes extraordinary refractive index at 20°C and 589 nm, n 0 denotes ordinary refractive index at 20°C and 589 nm, ⁇ denotes optical anisotropy at 20°C and 589 nm,
  • ⁇ 1 1 denotes dielectric permittivity parallel to the director at 20°C and 1 kHz
  • ⁇ denotes dielectric permittivity perpendicular to the director at
  • ⁇ denotes dielectric anisotropy at 20°C and 1 kHz
  • T(N,I) denotes clearing point [°C]
  • ⁇ denotes rotational viscosity measured at 20°C [mPa s], determined by the rotation method in a magnetic field
  • Ki denotes elastic constant
  • splay deformation at 20°C [pN]
  • K2 denotes elastic constant
  • twist deformation at 20°C [pN]
  • K3 denotes elastic constant, "bend” deformation at 20°C [pN],
  • threshold voltage for the present invention relates to the capacitive threshold (Vo), unless explicitly indicated otherwise.
  • the optical threshold can also be indicated for 10% relative contrast (V10).
  • a liquid-crystal mixture B-1 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.
  • a liquid-crystal mixture B-2 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.
  • PPTUI-3-4 25.00% ⁇ [mPa-s, 20°C]:
  • a liquid-crystal mixture B-3 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.
  • a liquid-crystal mixture B-4 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.
  • a liquid-crystal mixture B-5 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.
  • a liquid-crystal mixture B-6 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.
  • a liquid-crystal mixture B-7 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.
  • a liquid-crystal mixture B-8 is prepared and characterized with respect to its general physical properties, having the composition and properties as indicated in the following table.
  • PPTUI-3-4 15.00% ⁇ [mPa-s, 20°C]:
  • Nanocapsules LC mixture B-1 (2.00 g), hexadecane (100 mg), ethylene dimethacrylate (660 mg), hydroxyethylmethacrylate (75 mg) and methylmethacrylate (165 mg) are weighed into a 250 ml tall beaker.
  • Brij L23 (300 mg) is weighed into a 250 ml conical flask and water (100 ml) is added. This mixture is then sonicated for 5 to 10 minutes.
  • the Brij aqueous surfactant solution is poured directly into the beaker containing the organics.
  • the mixture is turrax mixed for 10 minutes at 10,000 rpm. Once turrax mixing is complete, the crude emulsion is passed through a high-pressure homogenizer at 30,000 psi five times.
  • the mixture is charged into a flask and fitted with a condenser, and after adding 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) (20 mg) is heated to 75°C for four hours.
  • AAPH 2,2'-azobis(2-amidinopropane) dihydrochloride
  • the reaction mixture is cooled, filtered twice through a 1 ⁇ cloth, and then size analysis of the material is carried out on a Zetasizer (Malvern Zetasizer Nano ZS) instrument.
  • One part of the obtained sample is further used as is. Another part of the sample is concentrated before further use. This is carried out by centrifuge (Thermo Biofuge Stratos). A centrifuge tube is filled with the mixture and centrifuged at 4,000 rpm for 10 minutes, the supernatant is collected and put in a new tube and centrifuged at 15,000 rpm for 20 minutes. The resulting pellet is redispersed in 1 ml of the supernatant and sampled for testing.
  • centrifuge Thermo Biofuge Stratos
  • the obtained nanocapsules exhibit suitable physical and electro-optical characteristics and show suitable switching behaviour in response to an applied voltage.
  • the PVA (molecular weight M w of PVA: 31 k; 88% hydrolysed) is first washed to remove ions in a Soxhlet apparatus for 3 days.
  • the solid content of the filtered binder is measured 3 times and the average is calculated by weighing an empty DSC pan using a DSC microbalance, adding approximately 40 mg of the binder mixture to the DSC pan and recording the mass, placing the pan on a 60°C hotplate for 1 hour followed by 1 10°C hotplate for 10 min, removing the pan from the hotplate and allowing to cool, recording the mass of the dry pan, and calculating the solid content.
  • the obtained nanocapsule sample is initially checked by microscopy for unwanted clumping or lumping, and also after film forming.
  • the solid content of the concentrated nanocapsule suspension is measured, wherein the solid content of the sample is measured 3 times and the average is calculated.
  • the sample is weighed in an empty DSC pan using the DSC microbalance. Approximately 40 mg of the sample is added to the DSC pan and the mass is recorded. The pan is placed on a 60°C hotplate for 1 hour followed by 1 10°C hotplate for 10 min. The pan is removed from the hotplate and allowed to cool. The mass of the dry pan is recorded, and the solid content is calculated.
  • the prepared PVA is added to the concentrated nanocapsule sample, wherein the approximately 30% washed 31 k PVA mixture is added in a 2.5 ml vial, and then the nanocapsules are added to the vial. Ion-free water is added to give a total solids content of 20% of an approximately 0.5 g mixture, with a nanocapsules to PVA weight ratio of 40:60.
  • the mixture is stirred using a vortex stirrer and leaving the mixture on a roller overnight to allow the PVA to disperse.
  • the substrate used is IPS (in-plane switching) glass having ITO coated interdigitated electrodes with an electrode width of 4 ⁇ and a gap of 8 ⁇ .
  • the substrate is placed in a rack and plastic box for washing.
  • Deionised water is added and the sample is placed in a sonicator for 10 minutes.
  • the substrate is removed from the water and blotted with a paper towel to remove the excess water. Washing is repeated with acetone, 2-propanol (IPA) and finally water for ion-chromatography.
  • the substrate is then dried using a compressed air gun. The substrate is treated with UV-ozone for 10 minutes.
  • the composite system comprising the nanocapsules and the binder is then coated on the substrate.
  • 40 ⁇ _ of mixture are coated as a film using a coating machine (K Control Coater, RK PrintCoat Instruments, bar coating with k bar 1 , coating speed of 7).
  • the sample is dried at 60 °C for 10 minutes on a hotplate. The appearance of the film is recorded. Prepared films are stored in a dry box between measurements.
  • Film thickness is measured by removing the film from above the electrical contacts with a razor blade.
  • the film thickness is measured in the region of the middle electrode using a profilometer (Dektak XT surface profiler, Bruker) with a stylus force of 5 mg and a scan length of 3000 nm and a time of 30 s.
  • the measured film thickness is 6.5 ⁇ .
  • Electro-optical Properties The appearance of the film is checked by eye for uniformity and defects. Two electrodes are soldered to the glass. Voltage-transmission curves are measured.
  • Switching speeds are measured at 40°C and 25°C at 150 Hz modulation frequency.
  • Electro-optical performance is checked on a Display Measurement System (Autronic-Melchers), wherein the intensity of the back light is taken as 100% transmission T and the dark state between crossed polarizers is taken as 0% transmission T and wherein switching is performed at 1 kHz and 24 °C.
  • a Display Measurement System Alignment-Melchers
  • V90 is 57.5 V
  • the dark state transmission is 1 .3%
  • the bright state transmission is 19.7%.
  • LC mixture B-1 (1 .00 g), hexadecane (104 mg), ethylene dimethacrylate (332 mg), hydroxyethylmethacrylate (69 mg) and pentadecafluorooctanol (1 15 mg) are weighed into a 250 ml tall beaker.
  • Brij L23 (75 mg) is weighed into a 250 ml conical flask and water (70 ml) is added. This mixture is then sonicated for 5 to 10 minutes.
  • the Brij aqueous surfactant solution is poured directly into the beaker containing the organics.
  • the mixture is treated and investigated as described above in Comparative Example 1 .
  • the obtained nanocapsules exhibit suitable physical and electro-optical characteristics and show suitable switching behaviour in response to an applied voltage.
  • a composite system and a film comprising the obtained capsules and the binder are prepared as described above in Comparative Example 1 .
  • the measured film thickness is 4.5 ⁇ .
  • LC mixture B-1 (1 .00 g), hexadecane (105 mg), ethylene dimethacrylate (340 mg), hydroxyethylmethacrylate (73 mg) and pentadecafluorooctanol (1 15 mg) are weighed into a 250 ml tall beaker.
  • Brij L23 (75 mg) is weighed into a 250 ml conical flask and water (70 ml) is added. This mixture is then sonicated for 5 to 10 minutes.
  • the Brij aqueous surfactant solution is poured directly into the beaker containing the organics.
  • the mixture is treated and investigated as described above in Comparative Example 1 .
  • the obtained nanocapsules exhibit suitable physical and electro-optical characteristics and show suitable switching behaviour in response to an applied voltage.
  • a composite system and a film comprising the obtained capsules and the binder are prepared as described above in Comparative Example 1 .
  • the measured film thickness is 3.7 ⁇ .
  • V90 is 53.0 V
  • the dark state transmission is 2.8%
  • the bright state transmission is 14.2%.
  • hydroxyethylmethacrylate (166 mg), methylmethacrylate (67 mg) and 1 ,1 ,1 ,3,3,3-hexafluoroisopropyl acrylate (23 mg) are weighed into a 250 ml tall beaker.
  • Brij L23 (150 mg) is weighed into a 250 ml conical flask and water (100 ml) is added. This mixture is then sonicated for 5 to 10 minutes.
  • the Brij aqueous surfactant solution is poured directly into the beaker containing the organics.
  • the mixture is treated and investigated as described above in Comparative Example 1 .
  • the obtained nanocapsules exhibit favourable physical and electro-optical characteristics and show suitable switching behaviour in response to an applied voltage.
  • a composite system and a film comprising the obtained capsules and the binder are prepared as described above in Comparative Example 1 .
  • the measured film thickness is 4.2 ⁇ .
  • V90 is 81 .5 V
  • the dark state transmission is 2.1 %
  • the bright state transmission is 16.6%.
  • hydroxyethylmethacrylate (81 mg), methylmethacrylate (67 mg) and 1 ,1 ,1 ,3,3,3-hexafluoroisopropyl acrylate (1 17 mg) are weighed into a 250 ml tall beaker.
  • a composite system and a film comprising the obtained capsules and the binder are prepared as described above in Comparative Example 1 .
  • the measured film thickness is 5.2 ⁇ .
  • V90 132.5 V
  • the dark state transmission is 0.3%
  • the bright state transmission is 17.4%.
  • LC mixture B-1 (2.01 g), hexadecane (100 mg), ethylene dimethacrylate (330 mg), hydroxyethylmethacrylate (85 mg), methyl methacrylate (37 mg) and 1 ,1 ,1 ,3,3,3-hexafluoroisopropyl acrylate (450 mg) are weighed into a 250 ml tall beaker.
  • Brij L23 (150 mg) is weighed into a 250 ml conical flask and water (100 ml) is added. This mixture is then sonicated for 5 to 10 minutes.
  • the Brij aqueous surfactant solution is poured directly into the beaker containing the organics.
  • the mixture is treated and investigated as described above in Comparative Example 1 .
  • the obtained nanocapsules exhibit favourable physical and electro-optical characteristics and show suitable switching behaviour in response to an applied voltage.
  • a composite system and a film comprising the obtained capsules and the binder are prepared as described above in Comparative Example 1 .
  • the measured film thickness is 4.3 ⁇ .
  • V90 is 49.5 V
  • the dark state transmission is 3.2%
  • the bright state transmission is 19.1 %.
  • LC mixture B-8 (2.01 g), hexadecane (97 mg), ethylene dimethacrylate (645 mg), 2-hydroxyethyl methacrylate (166 mg), 1 ,1 ,1 ,3,3,3- hexafluoroisopropyl acrylate (23mg) and methyl methacrylate (67 mg) are weighed into a 250 ml tall beaker.
  • the Brij aqueous surfactant solution is poured directly into the beaker containing the organics.
  • the mixture is turrax mixed for 10 minutes at 10,000 rpm. Once turrax mixing is complete, the crude emulsion is circulated through a high-pressure homogenizer at 30,000 psi for eight minutes.
  • the mixture is charged into a flask and fitted with a condenser, and after adding 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) (20 mg) is heated to 70°C for four hours.
  • AAPH 2,2'-azobis(2-amidinopropane) dihydrochloride
  • the obtained capsules have an average size of 176 nm, as determined by dynamic light scattering (DLS) analysis (Zetasizer).
  • DLS dynamic light scattering
  • One part of the obtained sample is further used as is. Another part of the sample is concentrated before further use. This is carried out by centrifuge. A centrifuge tube is filled with the mixture and centrifuged at 6,500 rpm for 10 minutes, the supernatant is collected and put in a new tube and centrifuged at 15,000 rpm for 20 minutes. The resulting pellet is re-dispersed in 1 ml of the supernatant and sampled for testing.
  • the obtained nanocapsules exhibit favourable physical and electro-optical characteristics and show suitable switching behaviour in response to an applied voltage.
  • a composite system and a film comprising the obtained capsules and the binder are prepared analogous to Comparative Example 1 .
  • the prepared film has a thickness of 4.2 ⁇ .
  • the measured electro-optical parameter V50 is 48 V
  • the measured electro-optical parameter V90 is 82 V.
  • the Brij aqueous surfactant solution is poured directly into the beaker containing the organics.
  • the mixture is turrax mixed for 10 minutes at 10,000 rpm. Once turrax mixing is complete, the crude emulsion is ultra- sonicated on a Branson sonifier W450 at 50% amplitude for a total of six minutes.
  • the mixture is charged into a flask and fitted with a condenser, and after adding 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) (10 mg) is heated to 70°C for four hours.
  • AAPH 2,2'-azobis(2-amidinopropane) dihydrochloride
  • the obtained capsules have an average size of 191 nm, as determined by dynamic light scattering (DLS) analysis (Zetasizer).
  • DLS dynamic light scattering
  • One part of the obtained sample is further used as is.
  • Another part of the sample is concentrated before further use. This is carried out by centrifuge. A centrifuge tube is filled with the mixture and centrifuged at 6,500 rpm for 10 minutes, the supernatant is collected and put in a new tube and centrifuged at 15,000 rpm for 20 minutes. The resulting pellet is re-dispersed in 1 ml of the supernatant and sampled for testing.
  • the obtained nanocapsules exhibit favourable physical and electro-optical characteristics and show suitable switching behaviour in response to an applied voltage.
  • a composite system and a film comprising the obtained capsules and the binder are prepared analogous to Comparative Example 1 .
  • Example 6 LC mixture B-8 (2.01 g), 2,2,3,3,3-pentafluoropropylacrylate (1 17 mg), ethylene dimethacrylate (663 mg), 2-hydroxyethyl methacrylate (81 mg) and methyl methacrylate (167 mg) are weighed into a 250 ml tall beaker.
  • Brij L23 (100 mg) is weighed into a 250 ml conical flask and water (100 g) is added. This mixture is then sonicated for 5 to 10 minutes.
  • the Brij aqueous surfactant solution is poured directly into the beaker containing the organics.
  • the mixture is turrax mixed for 10 minutes at 10,000 rpm. Once turrax mixing is complete, the crude emulsion is circulated through a high-pressure homogenizer at 30,000 psi for eight minutes. The mixture is charged into a flask and fitted with a condenser, and after adding 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) (20 mg) is heated to 70°C for four hours. The reaction mixture is cooled, filtered, and then size analysis of the material is carried out by Zetasizer instrument.
  • AAPH 2,2'-azobis(2-amidinopropane) dihydrochloride
  • the obtained capsules have an average size of 191 nm, as determined by dynamic light scattering (DLS) analysis (Zetasizer).
  • DLS dynamic light scattering
  • One part of the obtained sample is further used as is.
  • Another part of the sample is concentrated before further use. This is carried out by centrifuge. A centrifuge tube is filled with the mixture and centrifuged at 6,500 rpm for 10 minutes, the supernatant is collected and put in a new tube and centrifuged at 15,000 rpm for 20 minutes. The resulting pellet is re-dispersed in 1 ml of the supernatant and sampled for testing.
  • the obtained nanocapsules exhibit favourable physical and electro-optical characteristics and show suitable switching behaviour in response to an applied voltage.
  • a composite system and a film comprising the obtained capsules and the binder are prepared analogous to Comparative Example 1 .
  • the prepared film has a thickness of 5.2 ⁇ .
  • the measured electro-optical parameter V50 is 80 V
  • the measured electro-optical parameter V90 is 132 V.
  • LC mixture B-8 (2.00 g), 2,2,3,3,4,4,4-heptafluorobutylacrylate (1 17 mg), ethylene dimethacrylate (659 mg), 2-hydroxyethyl methacrylate (79 mg) and methyl methacrylate (170 mg) are weighed into a 250 ml tall beaker.
  • Brij L23 100 mg is weighed into a 250 ml conical flask and water (100 g) is added. This mixture is then sonicated for 5 to 10 minutes.
  • the Brij aqueous surfactant solution is poured directly into the beaker containing the organics.
  • the mixture is turrax mixed for 10 minutes at 10,000 rpm. Once turrax mixing is complete, the crude emulsion is circulated through a high-pressure homogenizer at 30,000 psi for eight minutes.
  • the mixture is charged into a flask and fitted with a condenser, and after adding 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) (20 mg) is heated to 70°C for four hours.
  • AAPH 2,2'-azobis(2-amidinopropane) dihydrochloride
  • the obtained capsules have an average size of 147 nm, as determined by dynamic light scattering (DLS) analysis (Zetasizer). One part of the obtained sample is further used as is.
  • DLS dynamic light scattering
  • Another part of the sample is concentrated before further use. This is carried out by centrifuge. A centrifuge tube is filled with the mixture and centrifuged at 6,500 rpm for 10 minutes, the supernatant is collected and put in a new tube and centrifuged at 15,000 rpm for 20 minutes. The resulting pellet is re-dispersed in 1 ml of the supernatant and sampled for testing.
  • the obtained nanocapsules exhibit favourable physical and electro-optical characteristics and show suitable switching behaviour in response to an applied voltage.
  • a composite system and a film comprising the obtained capsules and the binder are prepared analogous to Comparative Example 1 .
  • the prepared film has a thickness of 4.9 ⁇ .
  • the measured electro-optical parameter V50 is 77.5 V, and the measured electro-optical parameter V90 is 130 V.
  • LC mixture B-8 (2.01 g), 1 H,1 H,2H,2H-perfluorodecylacrylate (1 13 mg), ethylene dimethacrylate (657 mg), 2-hydroxyethyl methacrylate (75 mg) and methyl methacrylate (171 mg) are weighed into a 250 ml tall beaker.
  • Brij L23 (100 mg) is weighed into a 250 ml conical flask and water (100 g) is added. This mixture is then sonicated for 5 to 10 minutes. The Brij aqueous surfactant solution is poured directly into the beaker containing the organics. The mixture is turrax mixed for 10 minutes at 10,000 rpm. Once turrax mixing is complete, the crude emulsion is circulated through a high-pressure homogenizer at 30,000 psi for eight minutes.
  • the mixture is charged into a flask and fitted with a condenser, and after adding 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) (20 mg) is heated to 70°C for four hours.
  • AAPH 2,2'-azobis(2-amidinopropane) dihydrochloride
  • the obtained capsules have an average size of 188 nm, as determined by dynamic light scattering (DLS) analysis (Zetasizer).
  • DLS dynamic light scattering
  • One part of the obtained sample is further used as is.
  • Another part of the sample is concentrated before further use. This is carried out by centrifuge. A centrifuge tube is filled with the mixture and centrifuged at 6,500 rpm for 10 minutes, the supernatant is collected and put in a new tube and centrifuged at 15,000 rpm for 20 minutes. The resulting pellet is re-dispersed in 1 ml of the supernatant and sampled for testing.
  • the obtained nanocapsules exhibit favourable physical and electro-optical characteristics and show suitable switching behaviour in response to an applied voltage.
  • a composite system and a film comprising the obtained capsules and the binder are prepared analogous to Comparative Example 1 .
  • the prepared film has a thickness of 5.3 ⁇ .
  • the measured electro-optical parameter V50 is 75 V, and the measured electro-optical parameter V90 is 1 15 V.
  • Example 9 10. 1 1 . 12, 13 and 14 Example 4 is repeated, wherein however LC mixture B-8 is respectively replaced by LC mixtures B-2, B-3, B-4, B-5, B-6 and B-7.

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Abstract

La présente invention se rapporte à des compositions pour la nanoencapsulation, qui comprennent le milieu mésogène tel que décrit dans la revendication 1, un ou plusieurs composés polymérisables, au moins l'un du ou des composés polymérisables étant un composé polymérisable contenant du fluor, et un ou plusieurs tensioactifs, à des nanocapsules contenant le milieu mésogène et à leur utilisation dans des dispositifs électro-optiques.
PCT/EP2018/058962 2017-04-10 2018-04-09 Composition pour la nanoencapsulation et nanocapsules comprenant un milieu à cristaux liquides WO2018189068A1 (fr)

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EP3399006A3 (fr) * 2017-04-13 2019-03-20 LG Display Co., Ltd. Dispositif d'affichage à cristaux liquides comprenant une capsule à cristaux liquides et son procédé de fabrication
WO2019110458A1 (fr) * 2017-12-06 2019-06-13 Merck Patent Gmbh Milieu à cristaux liquides destiné à être utilisé dans un élément de commutation
WO2020229434A1 (fr) * 2019-05-15 2020-11-19 Merck Patent Gmbh Procédé de préparation d'un élément de commutation à base de cristaux liquides
GB2587254A (en) * 2019-05-28 2021-03-24 Merck Patent Gmbh Compositions comprising waterborne polyurethane dispersion and nanocapsules containing a liquid-crystalline medium

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EP3399006A3 (fr) * 2017-04-13 2019-03-20 LG Display Co., Ltd. Dispositif d'affichage à cristaux liquides comprenant une capsule à cristaux liquides et son procédé de fabrication
US11073714B2 (en) 2017-04-13 2021-07-27 Lg Display Co., Ltd. Liquid crystal display device including liquid crystal capsule and method of fabricating the same
US11619842B2 (en) 2017-04-13 2023-04-04 Lg Display Co., Ltd. Liquid crystal display device including liquid crystal capsule and method of fabricating the same
WO2019110458A1 (fr) * 2017-12-06 2019-06-13 Merck Patent Gmbh Milieu à cristaux liquides destiné à être utilisé dans un élément de commutation
US11760931B2 (en) 2017-12-06 2023-09-19 Merck Patent Gmbh Liquid-crystalline medium for use in a switching element
WO2020229434A1 (fr) * 2019-05-15 2020-11-19 Merck Patent Gmbh Procédé de préparation d'un élément de commutation à base de cristaux liquides
GB2587254A (en) * 2019-05-28 2021-03-24 Merck Patent Gmbh Compositions comprising waterborne polyurethane dispersion and nanocapsules containing a liquid-crystalline medium
GB2587254B (en) * 2019-05-28 2023-05-24 Merck Patent Gmbh Compositions comprising waterborne polyurethane dispersion and nanocapsules containing a liquid-crystalline medium

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