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WO2001096010A1 - Encapsulation photostimulee par separation des phases - Google Patents

Encapsulation photostimulee par separation des phases Download PDF

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Publication number
WO2001096010A1
WO2001096010A1 PCT/CA2001/000869 CA0100869W WO0196010A1 WO 2001096010 A1 WO2001096010 A1 WO 2001096010A1 CA 0100869 W CA0100869 W CA 0100869W WO 0196010 A1 WO0196010 A1 WO 0196010A1
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WIPO (PCT)
Prior art keywords
polymer
microcapsules
liquid
moieties
azobenzene
Prior art date
Application number
PCT/CA2001/000869
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English (en)
Inventor
Harald D. H. STÖVER
Anna Shulkin
Original Assignee
Mcmaster University
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Filing date
Publication date
Application filed by Mcmaster University filed Critical Mcmaster University
Priority to AU2001267215A priority Critical patent/AU2001267215A1/en
Publication of WO2001096010A1 publication Critical patent/WO2001096010A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
    • A01N25/00—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests
    • A01N25/26—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests in coated particulate form
    • A01N25/28—Microcapsules or nanocapsules
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
    • B01J13/02—Making microcapsules or microballoons
    • B01J13/06—Making microcapsules or microballoons by phase separation
    • B01J13/10—Complex coacervation, i.e. interaction of oppositely charged particles

Definitions

  • the present invention relates to microcapsules, to methods of making them, and to their use .
  • Microcapsules and matrices containing an encapsulated active ingredient are known for many purposes. In some instances, slow release of the encapsulated ingredient is required.
  • Materials that have been encapsulated in microcapsules and hydrogel matrices include pharmaceuticals, pesticides, fungicides, herbicides, bactericides, dyes, inks, chemical reagents and flavouring materials, and semiochemicals, that is materials that will modify the behaviour of animal species, for example pheromones .
  • insect pheromones are proving to be a biorational alternative to conventional hard pesticides.
  • attractant pheromones can be used effectively in controlling insect populations by disrupting the mating process.
  • small amounts of species-specific pheromone are dispersed over the area of interest during the mating season, raising the background level of pheromone to the point where the male insect cannot identify and follow the plume of attractant pheromone released by his female mate.
  • Polymer microcapsules are some of the delivery devices used to deliver the pheromone throughout the mating period of the insect, typically two to six weeks.
  • Polymer microcapsules in particular promise to serve as efficient delivery vehicles, as they: a) are easily prepared by a number of interfacial and precipitation polymerizations, b) enhance the resistance of the pheromone to oxidation and irradiation during storage and release, c) may in principle be tailored to control the rate of release of the pheromone fill,
  • One known method of forming pheromone-filled microcapsules involves dissolving pheromone and a diisocyanate in xylene and dispersing this solution into an aqueous solution followed by addition of a diamine.
  • a polyurea membrane forms rapidly at the interface between the continuous aqueous phase and the dispersed xylene droplets, resulting in formation of microcapsules containing the pheromone and xylene; see for example PCT international application WO 98/45036, Li, Nielson, Sengupta, published 15 October 1998.
  • this method is useful and yields valuable products it does have some limitations. For instance, isocyanates are highly reactive compounds and it is difficult to encapsulate compounds that react with the isocyanate. Hence, it is difficult to encapsulate compounds containing hydroxyl groups such as alcohols.
  • the present invention provides an encapsulation method that does not require use of an isocyanate reactant. Furthermore, the present invention provides a method to photochemically control microcapsule formation.
  • the present invention provides a method of preparing microcapsules which comprises dissolving or dispersing a radiation-sensitive polymer in a first liquid, dispersing the first liquid in a continuous phase of a second liquid that is more polar than the first liquid, and irradiating the polymer to increase its polarity, thereby causing it to migrate from the first liquid to the interface between the first and second liquids and form a membrane.
  • the invention extends to the microcapsules prepared. It is also possible to encapsulate
  • the invention also extends to microcapsules encapsulating such materials .
  • UN light of 360 nm wavelength causes azobenzenes to isomerize from the trans to the cis configuration.
  • Azobenzenes are much more polar in the cis configuration than in the trans configuration.
  • irradiation with light of 360 nm will cause the azobenzenes to isomerize to the more polar cis configuration.
  • the polymer will migrate from the oil phase to the aqueous phase, if the solubility parameters of the organic phase are suitable, i.e. if the organic phase is a near theta solvent for the polymer, and the polymer will form a membrane at the oil/water interface.
  • the solubility parameters of the organic phase are suitable, i.e. if the organic phase is a near theta solvent for the polymer, and the polymer will form a membrane at the oil/water interface.
  • the cis-trans isomerization of individual azobenzene molecules is reversible, as shown by the equation above, it is found that the formation of membranes by irradiation is not reversible.
  • Membrane-forming polymers in which azobenzene moieties can be incorporated include polymers that contain anhydride moieties, for example, styrene-maleic anhydride (SMA) copolymers .
  • SMA styrene-maleic anhydride
  • Such copolymers, containing 50% or more of styrene, are readily available, or readily made, and it is possible to modify a preformed SMA copolymer to incorporate azobenzene moities or to copolymerise an azobenzene-containing monomer with styrene and maleic anhydride or maleimide, or both maleic anhydride and maleimide.
  • an SMA-azobenzene copolymer by copolymerization of styrene, maleic anhydride and an azobenzene-containing monomer, for example a 4- phenylazomaleinanil, of formula:
  • R' is hydrogen, alkyl, alkoxy, alkoxyalkyl, amino, monoalkylamino or dialkylamino, the alkyl moieties containing up to 18, preferably up to 6, carbon atoms.
  • styrene and maleic anhydride are preferred' co-monomers for use with the azobenzene-containing moiety, it is possible to use other unsaturated polymerisable monomers in addition to, or instead of these. For instance it is possible to use styrene, ⁇ -met ylstyrene, or styrene or ⁇ -methylstyrene that is substituted in the benzene ring of the styrene moiety.
  • substituent mention is made of lower alkyl groups having up to 18 carbon atoms, preferably up to 6 carbon atoms.
  • the extra alkyl substituents on, for example, p-methylstyrene and p- tert . -butylstyrene render the copolymer less polar and more soluble in the water-immiscible solvents such as xylene and toluene that are preferred for use in interfacial reactions.
  • unsaturated copolymerisable monomers that may be present, in place of or in addition to styrene, include olefins such as ethylene, conjugated dienes such as 1, 3 -butadiene and isoprene, alkyl acrylates and methacrylates, especially lower alkyl such as the methyl, ethyl and, preferably, the butyl and ethylhexyl esters, vinyl acetate, acrylonitrile, methacrylonitrile, acrylamides, methacrylamides and unsaturated ethers such as alkyl vinyl ethers, for instance, the methyl and ethyl ethers.
  • olefins such as ethylene, conjugated dienes such as 1, 3 -butadiene and isoprene
  • alkyl acrylates and methacrylates especially lower alkyl such as the methyl, ethyl and, preferably, the butyl and ethylhexy
  • the azobenzene moiety can be introduced into a polymer in other ways.
  • an azobenzene compound bearing a reactive group can undergo a condensation reaction with pendant reactive groups of a polymer.
  • an azobenzene bearing a primary or secondary amino group can react with a glycidyl group pendant from a polymer chain.
  • a glycidyl group can be provided by polymerizing glycidyl acrylate or
  • Suitable unsaturated copolymerisable monomers include those mentioned above in the discussion of anhydride-containing copolymers .
  • polymers with acid chloride groups can condense with an azobenzene-containing compound that also bears a primary or secondary amino group or a hydroxy group
  • a preformed SMA copolymer can be reacted with an aminoazobenzene .
  • Attack of the aminoazobenzene on the anhydride moieties results in the formation of one carboxyl moiety and one amide moiety bearing the azobenzene, in accordance with the following equation:
  • the amino azobenzene can bear substituents, preferably in the 4' -position, i.e., R' in the formula of the aminoazobenzene can be, for example hydrogen, an alkyl group, an alkoxy group, an ether group, an amino group or a monoalkylamino or dialkylamino group, the alkyl moieties of these groups containing up to 18, preferably up to 6 carbon atoms .
  • the reaction can be carried out at reflux temperature in a polar solvent, for example tetrahydrofuran (THF) .
  • a polar solvent for example tetrahydrofuran (THF)
  • the functionalized polymer can be recovered by cooling in admixture with a non-polar solvent, for example heptane, to cause it to precipitate .
  • SMA can be reacted with a hydroxy-azobenzene compound, resulting in the opening of an anhydride moiety and the formation of a carboxyl moiety and an ester moiety bearing the azobenzene .
  • Styrene-maleic anhydride copolymers containing 50 mol% or more of styrene are readily available commercially, or are readily prepared. Any of these can be used, although it is preferred that the copolymer contains at least about 5 mol%, more preferably at least about 14 mol% of maleic anhydride.
  • the number of anhydride moieties present in the copolymer, and the number of those maleic anhydrides that are reacted with an azobenzene-containing compound will determine the frequency of the occurrence of radiation-sensitive groups along the polymer chain. This clearly can be controlled by the choice of the molar ratio of maleic anhydride moieties to azobenzene- containing compound. Preferably this ratio may be in the range from 1:1 to 20:1, more preferably in the range from 1:1 to 5:1.
  • maleic anhydride moieties have been used in the incorporation of the photoreactive azobenzene moiety in a polymer.
  • Other unsaturated polymerisable monomers that contain anhydride moieties can be used in addition to, or instead of, maleic anhydride for this purpose.
  • these other anhydride moieties include itaconic anhydride, citraconic (methylmaleic) anhydride, ethylmaleic anhydride, 1, 2-cyclohexene-l, 2-dicarboxylic acid anhydride and 1, 2-cyclohexene-4, 5-dicarboxylic acid anhydride.
  • an SMA copolymer reacted with stoichiometric amounts of 4-aminoazobenzene will contain free carboxyl groups. After the irradiation, these carboxyl groups can be coupled with, for instance, polyamines or polyols, especially in the presence of suitable water-soluble coupling reagents such as l-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride (EDAC) .
  • EDAC l-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride
  • EDAC l-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride
  • EDAC l-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride
  • EDAC l-ethyl-3- (3-dimethylaminopropyl) carbodiimi
  • Suitable water-soluble primary and secondary polyamines preferably primary diamines include those of formula (I) :
  • n is an integer from 2 to 10, preferably 2 to 6.
  • mixed primary/secondary amines include those of formula (II) :
  • m is an integer from 1 to 1,000, preferably 1 to 10, and R is hydrogen or a methyl or ethyl group.
  • R is hydrogen or a methyl or ethyl group.
  • TEPA tetraethylenepentamine
  • Suitable primary/secondary/tertiary amines include compounds like those
  • polyetheramines of general formula (III) are also suitable.
  • r is an integer from 1 to 20, preferably 2 to 15, more preferably 2 to 10, and R is hydrogen, methyl or ethyl.
  • R is hydrogen, methyl or ethyl.
  • the amine must contain at least two amino groups capable of reacting with the anhydride, i.e., primary or secondary amino groups.
  • the compound must be, at least, a diamine, but it may contain more than two amino groups; see for example compounds of formula (II) .
  • diamine is used to indicate a compound that has at least two reactive amino groups, but the term does not necessarily exclude reactants that contain more than two amino groups. Similar remarks apply to the term "diol" .
  • Reactants that can be used in post-irradiation reaction also include compounds that contain both amino and
  • the reaction between, for example, maleic anhydride and polyamine results in the opening of the anhydride ring with the formation of one amide moiety and one ammonium salt moiety between a carboxyl group and an amine.
  • the membrane formed is, in part, ionic. It is possible to subject this product to elevated temperature to dehydrate it to form a maleimide .
  • a material is to be encapsulated in the microcapsules formed, that material is dissolved or dispersed in the first liquid, together with the radiation-sensitive polymer. This material must not be so reactive with the polymer that it interferes with the radiation-induced reaction of the polymer.
  • Alcohols can be encapsulated. The ability to encapsulate alcohols is of particular significance.
  • the pheromone of the codling moth is E,E-8,10-C ⁇ 2 alcohol and it has been difficult to encapsulate this pheromone by the previously known technique involving isocyanate.
  • the present invention permits encapsulation of alcoholic compounds, including alcoholic pheromones and should permit encapsulation of codling moth pheromone.
  • a catalyst can be incorporated with the amine in the aqueous phase to speed post-irradiation reactions with polyamines or polyols.
  • Suitable catalysts include tertiary amines.
  • the tertiary amine in the amount used, should be freely soluble in the water present in the reaction mixture.
  • the simplest tertiary amine is trimethylamine and this compound, and its C 2 , C 3 and C 4 homologues can be used. It is of course possible to use tertiary amines containing a mixture of alkyl groups, for instance methyldiethylamine .
  • the tertiary amines containing a mixture of alkyl groups for instance methyldiethylamine .
  • 10 amine can contain more than one tertiary amine moiety. It may also contain other functional groups provided that those other functional groups do not interfere with the required reaction, or the functional groups participate beneficially in the required reaction. As an example of a functional group that does not interfere there is mentioned an ether group. As examples of groups that participate there are mentioned primary and secondary amine groups, and hydroxyl groups. Examples of suitable tertiary amines include compounds of the following structures:
  • triethylamine TAA
  • TAA triethylamine
  • the amount of the tertiary amine required is not very great. It is conveniently added in the form of a solution containing 0.5g of TEA per lOmL of water. Usually 0.5% by
  • Catalysts other than tertiary amines can be used.
  • Metal salts that are soluble in an organic solvent used as the first liquid can be used. Mention is made of titanium tetraalkoxides available under the trademark Tyzor from DuPont, and stannous octanoate, although these should not be used when there is also present in the organic solvent an alcohol to be encapsulated.
  • Suitable polyols include diols of formula (IV) :
  • n is an integer from 2 to 10, preferably 2 to 4 , and of formula (V) :
  • m is an integer from 1 to 10 and R is hydrogen or a methyl or ethyl group.
  • a catalyst can be used and suitable catalysts include the tertiary amines and other catalysts mentioned above.
  • the first liquid that serves as the dispersed phase, is a liquid in which the radiation-sensitive polymer can be dispersed or dissolved and in which any material to be encapsulated can be dispersed or dissolved. It should be immiscible, or at least only partially miscible, with the second liquid. While the limits on what is meant by “partially miscible” are not precise, in general a substance is considered to be water-immiscible if its solubility in water is less than
  • the first liquid is a marginal solvent for the polymer reactant, and has a boiling point in the vicinity of 100°C. The properties of the first liquid, which will become encapsulated with the active material that is to be released, will affect the rate of release of that active material. Selection of a first liquid has to be made with these considerations in mind.
  • Suitable candidates for use as the first liquid include alkylbenzenes such as toluene and xylene, ethers such as methyl tert . -butyl ether, ketones such as methylisobutylketone, esters such as ethyl acetate and propyl acetate, halogenated aliphatic hydrocarbons such as dichloromethane, and aliphatic nitriles such as butyronitrile . Mixtures of solvents can be used. There can also be used co- solvents to change the properties of solvents or solvent mixtures. As co-solvents there are mentioned aliphatic liquids such as kerosene and also cyclic hydrocarbons such as cyclohexane.
  • styrene-maleic anhydride copolymer containing 14% maleic anhydride is soluble in all of these solvents, whereas copolymer containing 50% maleic anhydride is soluble only in ethylacetate, dichloromethane and butyronitrile .
  • the second liquid that forms the continuous phase is preferably water or an aqueous solution with water as the major component, or another polar solvent.
  • the first liquid shall be a near theta solvent for the particular polymer, that it shall be immiscible with the second liquid, or at least not completely miscible with the second liquid, shall have a relatively high
  • Surfactants and emulsifiers can be used to assist in dispersion of the first liquid, i.e. the oil phase, in the second liquid.
  • IGEPAL 630 indicating a molecular weight of about 630, is mentioned. IGEPAL 630 is preferred to poly (vinylalcohol) as it results in smaller microcapsules.
  • Other suitable surfactants and emulsifiers include polyethyleneglycol alkyl ethers, for example, C ⁇ 8 H 35 (OCH 2 CH 2 ) n OH, where n has an approximate value of about 20, available under the trade-mark BRIJ 98.
  • Ionic surfactants can be used.
  • Sodium dodecyl sulphate (SDS) is mentioned as an example of an anionic surfactant .
  • the first liquid can be dispersed in the second liquid by dropping the first liquid into a stirred bath of the second liquid.
  • the first liquid then forms droplets throughout the continuous phase of the second liquid.
  • the reaction mixture is then irradiated to change the polarity of the polymer and cause capsule formation.
  • Any second reactant for post-irradiation reaction to enhance the membrane formation may be present in the second liquid before the first liquid is added.
  • the second reactant is not present in the second liquid when the first liquid has been dispersed, but is added subsequently, after irradiation.
  • the membrane forming raction can be carried out at any temperature between about 0°C and about 70°C, preferably between about 10°C and about 40°C. Most preferably the reaction is carried out at about room temperature, i.e. about 20 to about 25°C.
  • the lamp used to irradiate may also give off heat, so it may be desirable to apply cooling.
  • R is an alkyl group, for instance a methyl or ethyl group .
  • insect pheromones As examples of materials to be encapsulated, particular mention is made of insect pheromones. In the notation used below to describe the structure of the pheromones, the type (E or Z) and position of the double bond or bonds are given first, the number of carbon atoms in the chain is given next and the nature of the end group is given last. To illustrate, the pheromone Z-10 C19 aldehyde has the structure :
  • Pheromones may in fact be mixtures of compounds with one component of the mixture predominating, or at least being a significant component. Mentioned as examples of significant or predominant components of insect pheromones, with the target species in brackets, are the following: E/Z-ll C14 aldehyde
  • An example of a ketone that is a pheromone is E or Z 7-tetradecen-2-one, which is effective with the oriental beetle.
  • An ether that is not a pheromone but is of value is 4- allylanisole, which can be used to render pine trees unattractive to the Southern pine beetle.
  • the product of the microencapsulation process is a plurality of microcapsules having a size in the range of from about 1 ⁇ m to about 5000 ⁇ m, preferably 20 ⁇ m to 2000 ⁇ m. Particularly preferred microcapsules have sizes in the range from about 10 ⁇ m to about 60 ⁇ m, more preferably about 20 to about 30 ⁇ m, and an encapsulated pheromone contained within the membrane.
  • the microcapsules can be used in suspension in water to give a suspension suitable for aerial spraying.
  • the suspension may contain a suspending agent, for instance a gum suspending agent such as guar gum, rhamsan gum or xanthan gum.
  • Suitable light stabilizers include the tertiary phenylene diamine compounds disclosed in Canadian Patent No.
  • the light stabilizer can be incorporated by dissolving it, with the pheromone, in the oil phase.
  • Antioxidants and UV absorbers can also be incorporated. Many hindered phenols are known for this purpose. Mention is made of antioxidants available from Ciba-Geigy under the trade-marks Irganox 1010 and 1076. As UN absorbers there are mentioned Tinuvin 292, 400, 123 and 323 available from Ciba-Geigy.
  • a coloured dye or pigment in the microcapsules.
  • the dye should be oil-soluble and can be incorporated, with the pheromone, in the oil phase.
  • an oil-soluble or oil- dispersible dye can be included in the aqueous suspension of microcapsules, where it is absorbed by the microcapsule shell.
  • Suitable oil-soluble or oil-dispersible dyes can be obtained from DayGlo Color Corporation, Cleveland, Ohio, and include Blaze Orange, Saturn Yellow, Aurora Pink, and the like.
  • mercaptans Other compounds of interest for encapsulation and controlled release include mercaptans .
  • Ingredients in the urine of such animals include mercaptans.
  • the urine of a wolf includes a mercaptan, and distribution of microcapsules from which this mercaptan is gradually released to define a territory will discourage deer from entering that territory.
  • microcapsules of the invention include perfumes, pharmaceuticals, fragrances, flavouring agents and the like.
  • microcapsules of this invention are pH-sensitive .
  • the microcapsules shrink in acid and swell in base. Release of encapsulated material is slowed when the microcapsules are shrunken and is accelerated when the microcapsules are swollen.
  • styrene-maleic anhydride- azobenzene copolymers are biocompatible, microcapsules of the invention can be used to supply pH-sensitive pharmaceutical materials to the intestine. In the acidic stomach environment the microcapsules are shrunken and little or no release of active ingredient occurs. On entering the intestine, with its alkaline environment, the microcapsules swell and release of encapsulated active ingredient occurs .
  • Figures 1A and IB are environmental scanning electron microscope (ESEM) images of microcapsules prepared in Example 5;
  • Figures 2A and 2B are ESEM images of microcapsules prepared in Example 6;
  • Figures 3A and 3B are optical photomicrographs of capsules formed in Example 7.
  • Poly (styrene-maleic anhydride) of 50% maleic anhydride content was obtained from Aldrich, and was also prepared according to the procedure described below.
  • Poly (styrene-maleic anhydride), with 32% and 14% maleic anhydride content, 4 -aminoazobenzene, maleic anhydride, 4- phenylazomaleinanil (PAMA) , N-phenylmaleimide (PMA) and methylethylketone were obtained from Aldrich and used as received.
  • Styrene was purchased from Aldrich, and passed neat through a short alumina column to remove inhibitors .
  • Table 2 shows styrene-maleimide based azobenzene functionalized copolymer.
  • Table 3 shows styrene-maleic anhydride based azobenzene- functionalized copolymers.
  • a UN reactor consisting of a set of 8 Rayonet photochemical reactor lamps RPR-3500A lining the inner wall of a vertical aluminum cylinder of 12 cm diameter, cooled with a small fan, was used for the irradiations.
  • ESEM Environmental Scanning Electron Microscope
  • the oil phase consisting of a solution of one of the azobenzene functionalized polymers in a suitable solvent or solvent mixture, was dispersed in an aqueous phase containing an emulsifier.
  • the resulting emulsion was irradiated at 350 nm at room temperature for about an hour, after which time the emulsion droplets had turned into liquid-filled polymer microcapsules .
  • the polymer phase separated from the solvent during irradiation, and migrated to the organic/water interface to form the capsule wall .
  • microcapsules prepared from S-PAMA50, mol. wt . 15,000 in methyl isobutyl ketone 100 mL deionized water containing lg polyvinylalcohol (80% hydrolyzed, 9000 - 10000 Da) was placed into a 200 mL beaker, stirred at 450 rpm, and the oil phase consisting of 0.5g S-PAMA50 dissolved in 10 mL methylisobutylketone was added dropwise over 60 seconds to form an oil-in-water emulsion. After an additional 20 min of stirring, the emulsion was transferred to a UN-reactor and irradiated for 1 hr. A glass cold finger was submerged into the emulsion to keep its temperature near room temperature. Following irradiation, the resulting aqueous dispersion of microcapsules was stored at room temperature.
  • Figures 1A and IB show environmental scanning electron microscope (ESEM) images of microcapsules prepared by irradiating aqueous emulsions of methylisobutylketone containing 5% by weight of S-PAMA50.
  • ESEM environmental scanning electron microscope
  • the concentration of copolymer in the organic phase is reflected in the shell thickness of the microcapsules. Lowering the polymer content of the oil phase produces thinner shells, as seen from electron micrographs of the fractured microcapsules prepared from emulsions with 5% of copolymer and 10% of copolymer ( Figures IB and 2B) .
  • Lower polymer concentration narrows the microcapsule size distribution, and decreases the average size of the capsules.
  • a higher concentration of the polymer in the droplet phase leads to the formation of correspondingly larger droplets because more viscous liquids are less easily broken up to smaller droplets.
  • Styrene-maleimide based copolymers with less than 50% of UN-sensitive groups were also prepared. It was found that S-PAMA10-PMA 0 copolymer, which has only 10% of UN- sensitive groups precipitates out upon UN-irradiation from the mixture THF/heptane (3/1) and also from ethylene glycol dimethyl ether. This result indicates that 10% of photosensitive groups on the polymer is enough to cause the
  • the copolymers with high content of PAMA are more hydrophobic than the copolymers with low content of PAMA. It is indicated that PAMA is a more hydrophobic monomer than PMA.
  • Capsules were prepared from S-PAMA30-PMA20, mol. wt . 32,000 dissolved in toluene/aniline (8/1) and toluene/dichloromethane (6/1) mixtures according to the general procedure (Fig. 3A and 3B) .
  • the capsules were prepared at room temperature, stirring speed 450 rpm with sodium dodecyl sulphate (0.3%) as surfactant.
  • the aqueous phase was 100 mL in volume and in each case the oil phase consisted of 0.3 g of polymer in 7 mL of total organic phase .
  • Capsules in Figure 3A were made using a toluene/aniline (8/1) mixture as first liquid (core oil) and capsules in Figure 3B used a toluene/dichloromethane (6/1) mixture.

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Abstract

L'invention concerne un procédé de préparation de microcapsules, qui consiste à dissoudre ou à disperser dans un premier liquide un polymère sensible au rayonnement, à disperser le premier liquide dans une phase continue d'un deuxième liquide plus polaire que le premier liquide, et à irradier le polymère afin d'augmenter sa polarité et former une membrane. L'invention concerne en outre les membranes préparées selon le procédé de l'invention.
PCT/CA2001/000869 2000-06-12 2001-06-12 Encapsulation photostimulee par separation des phases WO2001096010A1 (fr)

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AU2001267215A AU2001267215A1 (en) 2000-06-12 2001-06-12 Photostimulated phase separation encapsulation

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CA 2311195 CA2311195A1 (fr) 2000-06-12 2000-06-12 Encapsulation par separation de phase photostimulee
CA2,311,195 2000-06-12

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Cited By (10)

* Cited by examiner, † Cited by third party
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WO2003097218A1 (fr) * 2002-05-16 2003-11-27 Mcmaster University Nouvelles tecto-membranes composites formees par reaction interfaciale entre des microspheres polymeriques reticulees et des agents de couplage
WO2005122758A1 (fr) * 2004-06-14 2005-12-29 Monsanto Technology Llc Microcapsules dans lesquelles un materiau noyau est libere activement
US20130039962A1 (en) * 2011-08-10 2013-02-14 Johan Smets Encapsulates
CN104861783A (zh) * 2015-04-21 2015-08-26 佛山市南方包装有限公司 一种含偶氮苯的微胶囊型液晶及其在光控液晶防伪油墨中的应用
US9877478B2 (en) 2009-02-13 2018-01-30 Monsanto Technology Llc Encapsulation of herbicides to reduce crop injury
US9913469B2 (en) 2010-08-18 2018-03-13 Monsanto Technology Llc Early applications of encapsulated acetamides for reduced injury in crops
US20210197099A1 (en) * 2018-05-31 2021-07-01 Battelle Memorial Institute Photoactive separation of solutes
US11129381B2 (en) 2017-06-13 2021-09-28 Monsanto Technology Llc Microencapsulated herbicides
US11140900B2 (en) 2014-01-27 2021-10-12 Monsanto Technology Llc Aqueous herbicidal concentrates
US11419331B2 (en) 2019-01-30 2022-08-23 Monsanto Technology Llc Microencapsulated acetamide herbicides

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3405071A (en) * 1963-12-30 1968-10-08 Ibm Process of making microcapsules
JPS54119373A (en) * 1978-03-09 1979-09-17 Agency Of Ind Science & Technol Preparation of microcapsule
JPS63256129A (ja) * 1987-04-14 1988-10-24 Yoshiharu Tsujita ベシクル混合物とベシクル構造の制御方法

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3405071A (en) * 1963-12-30 1968-10-08 Ibm Process of making microcapsules
JPS54119373A (en) * 1978-03-09 1979-09-17 Agency Of Ind Science & Technol Preparation of microcapsule
JPS63256129A (ja) * 1987-04-14 1988-10-24 Yoshiharu Tsujita ベシクル混合物とベシクル構造の制御方法

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 003, no. 142 (C - 065) 24 November 1979 (1979-11-24) *
PATENT ABSTRACTS OF JAPAN vol. 013, no. 063 (C - 568) 13 February 1989 (1989-02-13) *

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WO2003097218A1 (fr) * 2002-05-16 2003-11-27 Mcmaster University Nouvelles tecto-membranes composites formees par reaction interfaciale entre des microspheres polymeriques reticulees et des agents de couplage
WO2005122758A1 (fr) * 2004-06-14 2005-12-29 Monsanto Technology Llc Microcapsules dans lesquelles un materiau noyau est libere activement
US12239130B2 (en) 2009-02-13 2025-03-04 Monsanto Technology Llc Encapsulation of herbicides to reduce crop injury
US9877478B2 (en) 2009-02-13 2018-01-30 Monsanto Technology Llc Encapsulation of herbicides to reduce crop injury
US10813352B2 (en) 2009-02-13 2020-10-27 Monsanto Technology Llc Encapsulation of herbicides to reduce crop injury
US9913469B2 (en) 2010-08-18 2018-03-13 Monsanto Technology Llc Early applications of encapsulated acetamides for reduced injury in crops
US11412734B2 (en) 2010-08-18 2022-08-16 Monsanto Technology Llc Early applications of encapsulated acetamides for reduced injury in crops
US20130039962A1 (en) * 2011-08-10 2013-02-14 Johan Smets Encapsulates
CN103747771A (zh) * 2011-08-10 2014-04-23 宝洁公司 包封物
EP2741731B1 (fr) * 2011-08-10 2017-05-17 The Procter and Gamble Company Agents encapsulés
US9890351B2 (en) * 2011-08-10 2018-02-13 The Procter & Gamble Company Encapsulates
US11140900B2 (en) 2014-01-27 2021-10-12 Monsanto Technology Llc Aqueous herbicidal concentrates
CN104861783A (zh) * 2015-04-21 2015-08-26 佛山市南方包装有限公司 一种含偶氮苯的微胶囊型液晶及其在光控液晶防伪油墨中的应用
US11129381B2 (en) 2017-06-13 2021-09-28 Monsanto Technology Llc Microencapsulated herbicides
US11937599B2 (en) 2017-06-13 2024-03-26 Monsanto Technology Llc Microencapsulated herbicides
US20210197099A1 (en) * 2018-05-31 2021-07-01 Battelle Memorial Institute Photoactive separation of solutes
US12011678B2 (en) * 2018-05-31 2024-06-18 Battelle Memorial Institute Photoactive separation of solutes
US11419331B2 (en) 2019-01-30 2022-08-23 Monsanto Technology Llc Microencapsulated acetamide herbicides

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