WO2019007707A1

WO2019007707A1 - Process for producing omniphobic surfaces

Info

Publication number: WO2019007707A1
Application number: PCT/EP2018/066730
Authority: WO
Inventors: Michael Beckmann; Jakob SABLOWSKI; Simon Unz; Julia LINNEMANN; Lars Giebeler
Original assignee: Technische Universität Dresden; Leibniz-Institut Für Festkörper- Und Werkstoffforschung Dresden E.V.
Priority date: 2017-07-07
Filing date: 2018-06-22
Publication date: 2019-01-10
Also published as: DE102017211592A1; DE102017211592B4

Abstract

The invention relates to a process for coating components with an omniphobic surface coating containing at least one organometallic scaffold compound and an impregnating agent comprising the steps of - electrochemical deposition of the organometallic scaffold compound on the component by electrolysis from an electrolyte solution containing at least one metal ion, at least one linker compound and a solvent, - application of an impregnating agent onto the organometallic scaffold compound, wherein the metal ion is i) dissolved in the electrolyte solution as a metal ion salt and/or ii) by electrolytic oxidation or reduction of a metal ion precursor present in the component and/or electrode generated at the interface between the electrode and the electrolyte solution and/or provided in the electrolyte solution and wherein the component is a) simultaneously the electrode or b) introduced into an electrical field between at least two electrodes, wherein the linker compound is an organic, at least monodentate compound and wherein the impregnating agent has a low surface tension of < 30 mN/m.

Description

Process for producing omniphobic surfaces

The invention relates to a method for producing an omniphobic surface coating on components, the surface coating as such and their use in heat exchangers.

A vapor settles on a solid surface, such as a wall, as a liquid, as long as the temperature of the surface is below a saturated steam temperature of the vapor. This process is called condensation.

Condensation in heat exchangers is widely used in the efficient use of waste heat from industrial plants, with z. B. condensed vaporous water on the surface of a heat exchanger and can be used to heat, for example, air or hot water.

The condensation of the water vapor on the surface of the heat exchanger can take place with formation of a closed, coherent film (film condensation), which forms on the surface. But it can also be done as a drop condensation, in which the surface is wetted by spatially separated from each other drops.

The formation of a liquid film is often disturbing and undesirable. On the other hand, dropwise condensation is much more advantageous, since it is characterized by significantly higher heat transfer coefficients compared to film condensation.

It has therefore been the subject of research and development activities for a long time.

Most of the previous investigations on droplet condensation were carried out using the steam / water system.

There are different approaches to realize the droplet condensation of water vapor.

Thus, this can be achieved for example by a hydrophobic functionalization of the heat exchanger surface. The chemical and physical properties of the surface are changed so that it has the lowest possible wettability to water and thus large water contact angle. Such surfaces have a medium or low surface energy.

In the chemical functionalization of surfaces for droplet condensation, nonpolar molecules are bound to the surface by means of coating methods (see, inter alia, G. Koch, DC Zhang, A. Leipertz, M. Grischke, K. Trojan, and H. Dimigen, "Study on plasma J. Heat Mass Transfer, Vol. 41, No. 13, pp. 1899-1906, 1998, G. Koch, K. Kraft, and A. Leipertz, " Parameter study on the Performance of dropwise condensation ", Rev. Gen. Therm., Vol. 37, No. 7, p. 539- 548, 1998; G. Koch, DC Zhang, and A. Leipertz, "Condensation of Steam on the Surface of Hard Coated Copper Discs," Int. J. Heat Mass Transfer, Vol. 32, No. 3, pp. 149-156, 1997; MP Bonnar, BM Burnside, A. Little, RL Reuben, and JIB Wilson, "Plasma Polymer Films for Dropwise Condensation of Steam," Chem. Vap. Deposition, Vol. 3, No. 4, pp. 201-207, 1997; MP Bonnar, BM Burnside, J. Christie, EJ Sceal, CE Troupe, and JIB Wilson, "Hydrophobie Coatings from Plasma Polymerized Vinyl Trimethylsilanes", Chem. Vap. Deposition, Vol. 5, No. 3, pp. 1 17-125, 1999, R. Enright, N. Miljkovic, JL Alvarado, K. Kim, and JW Rose, "Dropwise Condensation on Microand Nanostructured Surfaces", Nanoscale Microscale Thermophys. Eng., Vol. 18, No. 3, pp. 223-250, 2014).

Furthermore, droplet condensation can be implemented by implanting atoms into the surface layer of the materials (see A. Bani Kananeh, MH Rausch, AP Froeba, and A. Leipertz, "Experimental study of dropwise condensation on plasma-ion implanted stainless steel tubes", J. Heat Mass Transfer, Vol. 49, No. 25-26, pp. 5018-5026, 2006 and MH Rausch, AP Froeba, and A. Leipertz, "Dropwise condensation heat transfer on ion-implanted aluminum surfaces", Int. J. Heat Mass Transfer, Vol. 51, No. 5-6, pp. 1061-1070, 2008).

In addition to the chemical properties of the condensation surface, the wetting and condensation behavior is also influenced by the surface morphology (see Figure 8).

Thus, a combination of water-repellent surface material and targeted structuring in the micro- and nanometer range produced superhydrophobic surfaces with very high water contact angles (Θ> 150 °) (see Fehler! Reference source could not be found b, see also KA Wier and TJ McCarthy , "Condensation on Ultrahydrophobic Surfaces and Its Effect on Droplet Mobility: Ultrahydrophobic Surfaces Are Not Always Water Repellant", Langmuir, Vol. 22, No. 6, pp. 2433-2436, 2006, JB Boreyko and C.-H. Rev. Lett., Vol. 103, No. 18, pp. 184501, 2009, and N. Miljkovic, R. Enright, and EN Wang, "Effect of Droplet Morphology" on "Self-Propelled Dropwise Condensate on Superhydrophobic Surfaces" Growth Dynamics and Heat Transfer during Condensation on Superhydrophobic Nanostructured Surfaces ", ACS Nano, Vol. 6, No. 2, pp. 1776-1785,

2012).

In addition, as shown in FIG. 1 (c), if the adhesion of the condensate drops to the surface is avoided, such surfaces allow a further increase in heat transfer in the condensation of water vapor compared to smooth hydrophobic surfaces (N. Miljkovic, R. Enright, and EN Wang, "Modeling and Optimization of Superhydrophobic Condensation," J. Heat Transfer, Vol. 135, No. 11, p. 1, 1 1004-1 1 1004,

2013). For the description of the heat transfer in drop condensation of organic and non-aqueous material systems lacking detailed studies. Thus, the application of the droplet condensation mechanism to increase the efficiency of apparatuses and processes in these material systems in practice has been difficult to implement.

Potential applications for droplet condensation of organic and non-aqueous systems include processes for solvent recovery as well as closed loop processes in heat pumps, chillers and Organic Rankine Cycle plants. Particularly in the case of the material systems used here, the use of drop condensation in comparison with film condensation is even more interesting and technically more relevant than with water vapor / water.

However, the condensing refrigerants and solvents as a common feature to a significantly lower surface tensions than water, which further complicates a realization of the drop condensation.

However, the heat transfer increased by droplet condensation makes this mechanism economically extremely interesting for a large number of technical processes. These include, for example, capacitors in ORC plants for power generation from waste heat or the stationary and mobile use of heat pumps and chillers.

An increased heat transfer in the condensation of the refrigerant advantageously leads to lower heat exchanger surfaces can be used for the same effect.

For example, savings of 20% to 30% of the heat transfer surface in comparison to film condensation can be achieved by water cooling and the used isobutane refrigerant by tripling the refrigerant side heat transfer by means of drop condensation. This allows the construction of very compact and weight-saving apparatus and a lower material usage. In this way, if the coating technologies are integrated in line with the market, the manufacturing costs for the apparatuses can also be reduced.

Also for production processes for the recovery of organic solvents from contaminated exhaust air, especially in the printing industry, in the coating and painting of wood, metal and plastic surfaces, in the production of pharmaceuticals and paints, paints and adhesives, the drop condensation is an economically attractive alternative to conventional methods.

So far, for example, adsorption or thermal or catalytic oxidation were used for the above process. The drop condensation allows, for example, in Contrary to the thermal or catalytic oxidation, a material use of the recovered solvent.

The relevant fluids from the group of refrigerants and solvents have as a common feature a significantly lower surface tension γι_ν than water. Usually this is <50 mN / m, often even <30 mN / m.

This usually leads to significantly lower contact angles compared to water. In the case of numerous, in particular hydrophobic surfaces, this even leads to complete wetting with the organic or anhydrous fluids. The realization of the droplet condensation is therefore considerably more difficult with these fluids.

The above-described approaches for the implementation of the droplet condensation of water vapor are therefore only of limited suitability for the relevant fluids from the group of refrigerants and solvents. Instead of hydrophobic surfaces it is necessary for the drop condensation of refrigerants and solvents omniphobic surfaces, which have a low wettability compared to a variety of polar and non-polar liquids. It is known from the literature that smooth omniphobic surfaces of very low surface energy ysv can be produced by coating with fully fluorinated systems (K. Rykaczewski, AT Paxson, M. Staymates, ML Walker, X. Sun, S. Anand, S. Srinivasan, GH McKinley, J. Chinn, JHJ Scott, and KK Varanasi, "Dropwise Condensation of Low Surface Tension Fluids on Omniphobic Surfaces", Sei. Rep., Vol. 4, Item No. 4158, 2014, TM Mayer, MP de Boer, ND Shinn, PJ Clews, and TA Michalske, "Chemical vapor deposition of fluoroalkylsilane monolayer films for adhesion control in microelectromechanical systems", J. Vac., See Technol. B, Vol. 18, No. 5, pp. 2433-2440, 2000, J. Tsibouklis and T. G. Nevell, "Ultra Low Surface Energy Polymers: The Molecular Design Requirements", Adv., Mater., Vol. 15, No. 7-8, pp. 647-650, 2003; Chhatre, JO Guardado, BM Moore, TS Haddad, JM Mabry, GH McKinley, and RE Cohen, "Fluoroalkylated Silicon-Containing Sur faces-Estimation of Solid-Surface Energy ", ACS Appl. Mater. Interfaces, Vol. 2, No. 12, pp. 3544-3554, 2010).

However, because of their low mechanical stability, such coatings are unsuitable for numerous industrial applications (J. GrÃ¶hle and J. Rühe, "Surfaces with Combined Microscale and Nanoscale Structures: A Route to Mechanically Stable Super Hydrophobic Surfaces", Langmuir, Vol 1 1, pp. 3765-3772, 2013).

As already described above, the wetting and condensation behavior is also influenced by the surface morphology. It is known that by combining a suitable surface morphology and impregnation of the surface with a suitable low surface energy lubricant, omniphobic surfaces can be produced. Recent studies show that surface hierarchical structuring (micrometer-scale patterning with additional roughness on the nanometer scale) is one way to minimize the adhesion of condensate droplets to the surface while increasing the durability of the impregnation.

In the publication by S. Anand et al. (Anand, AT Paxson, R. Dhiman, JD Smith, and KK Varanasi, "Enhanced Condensation on Lubricant-Impregnated Nanotextured Surfaces", ACS Nano, Vol. 6, No. 11, pp. 10122-10129, 2012). For example, by photolithography and subsequent etching, nanostructures are formed on the surface of a sample and then treated with an impregnant to achieve improved water droplet condensation.

Disadvantages are the hitherto known multistage processes for the production of hierarchical microstructures and nanostructures, which comprise, for example, photolithographic processes or the use of carbon nanotubes, extremely cost-intensive and less suitable for industrial processes, especially for the coating of complex components.

Components must be coated before final assembly and must no longer be welded, as otherwise the applied coating will be damaged. Likewise, an immersion bath for applying the layers for large and complex components would be unsuitable because the immersion size limits the size of components and complex components in an inhomogeneous coating is expected. This in turn would be a reason for increased corrosion.

An alternative possibility for structuring surfaces is the use of metal-organic frameworks (MOFs).

A favorable feature of the MOF are structurally based pores at the molecular level and a correspondingly high porosity and surface area. MOFs are also characterized by high stability or insolubility in almost all solvents and temperature resistance of up to 350 ° C. So far, applications in the field of catalysis, gas storage and purification as well as analytics have been known for MOF (AU Czaja, N. Trukhan, and U. Müller, "Industrial applications of metal-organic frameworks", Chem. Soc. Rev., Vol 38, No. 5, pp. 1284-1293, 2009.) Schüth, F., Chemie Ingenieur Technik, Vol. 82, No. 6 769-777, 2010, gives an overview of porous materials, which are particularly distinguished by their Among other things, MOFs are described which have a significantly larger pore size than zeolites and show pore sizes in the mesopore range

For the production of MOF coatings, various processes are known, which include both classical layer growth techniques such as spin coating processes, dip coating or spraying and stepwise reactive coatings (see K. Ariga et al., "Layer-by-layer nanoarchitectonics: invention, innovation, and evolution", Chem. Lett., Vol. 43, No. 1, pp. 36-68, 2014, D. Zacher, O. Shekhah , C. Wöll, and RA Fischer, "Thin films of metal-organic frameworks", Chem. Soc. Rev., Vol. 38, No. 5, pp. 1418-1429, 2009; C.-T. He et al., "Exceptional hydrophobicity of a large-pore metal-organic zeolite", J. Am. Chem. Soc., Vol. 137, No. 22, pp. 7217-7223, 2015, J. Zhao et al., "Conformal and highly adsorptive metal-organic framework thin films via layer-by-layer growth on ALD-coated fiber mats ", J. Mater. Chem. A, Vol. 3, No. 4, pp. 1458-1464, 2015; S. Liu, G. Liu, X. Zhao, and W. Jin, "Hydrophobic-ZIF-71 filled PEBA mixed matrix membranes for recovery of biobutanol via pervaporation", J. Membrane Sei., Vol. 446, p. 188, 2013).

Chun-Ting, H. et al. J. Am. Chem. Soc. 2015, 137, 7217-7223 discloses the preparation of microporous zeolites with uniform pore sizes. The zeolites are first synthesized in solution and the MOFs thus formed investigated as a powder. This high hydrophobicity is detected.

Furthermore, MOF layers can also be grown by low-cost industrially scalable electrochemical methods, wherein MOF synthesis and coating are realized directly in one step. Crystallite sizes and spacings and the associated layer thickness and surface morphology are controllable.

DE 10355087 A1 from 2003 describes a process for the electrochemical preparation of crystalline MOFs in powder form, from a reaction medium containing bidentate compounds and metal ions, which are provided by oxidation of an anode containing the corresponding metal.

Hartmann et al., Langmuir 2008, 24, 8643-8642 describes the preparation of copper-based MOFs, i.a. by means of electrochemical reaction. The linker molecule is initially introduced into the electrolyte and the MOF compound is prepared by electrolysis using copper electrodes.

Other publications followed, for example, Ameloot et al. (R. Ameloot, L. Stappers, J. Fransaer, L. Alaerts, BF Sels, and DE De Vos, "Patterned Growth of Metal-Organic Framework Coatings by Electrochemical Synthesis", Chem. Mater., Vol. 21, No. 13, pp. 2580-2582, 2009).

The electrochemical deposition of MOF on metals has also been reviewed in review articles (see, inter alia, H. Al-Kutubi, J. Gascon, EJR Sudhölter, and L. Rassaei, "Electrosynthesis of Metal-Organic Frameworks: Challenges and Opportunities." Chem Electro Chem, Vol 2, No. 4, pp. 462-474, 2015. or W.-J. Li, M. Tu, R. Cao, and RA Fischer, "Metal-organic framework thin films: electrochemical fabrication techniques and 3, Appl. Chem. A, Vol. 4, No. 32, pp. 12356-12369, 2016).

Campagnol et al. published for the first time studies on the mechanism of anodic deposition of organometallic skeletons. (Campagnol N., TRC van Assche, M. Li, L. Stappers, M. Dinca, JFM Denayer, K. Binnemans, DE De Vos and J. Fransaer, "On the electrochemical deposition of metal-organic frameworks", J. Mater. Chem. A, Vol. 4, No. 10, pp. 3914-3925, 2016).

With the extension to bipolar electroplating, it is also possible to coat complex components of any geometric shape (see, for example, BS Yadnum et al., "Site-Selective Synthesis of Janus-type Metal-Organic Framework Composites", Angew Chem., Vol. 15, p. 4082-4086, 2014).

On surfaces that work exclusively with an additional structuring in the micro and nanometer range, the condensation of fluids with very low surface tension, in contrast to the condensation of water vapor, is not directly associated with an increased heat transfer. Instead, in these cases dripping in the interstices leads to flooding of the surface structuring and formation of a closed condensate film (film condensation, see K. Rykaczewski et al., "Dropwise Condensation of Low Surface Tension Fluids on Omniphobic Surfaces", Sei. Rep., Vol. 4, Item No. 4158, 2014).

The formation of the condensate film can be prevented by additionally impregnating the micro- and nanostructured surfaces with an oil or lubricant.

To produce the nanostructured surfaces z. B. Rykaczewski et al. Silicon substrates coated with aluminum nanoparticles. After application of a fluoropolymer-based lubricant, improved heat transfer by dropwise condensation was observed for solvents with surface tensions of 15 to 28 mN / m (see also K. Rykaczewski et al., "Dropwise Condensation of Low Surface Tension Fluids on Omniphobic Surfaces", Sci 4, Item No. 4158, 2014; S. Anand, AT Paxson, R. Dhiman, JD Smith, and KK Varanasi, "Enhanced Condensation on Lubricant-Impregnated Nanotextured Surfaces," ACS Nano, Vol. 6, No. 11, pp. 10122-10129, 2012; R. Xiao, N. Miljkovic, R. Enright, and EN Wang, "Immersion condensation on oil-infused heterogeneous surfaces for enhanced heat transfer," Se. Rep. , Vol. 3, Article No. 1988, 2013).

US 2013/02208/13 A1 describes a process for producing impregnated micro / nano-structured surfaces for improving the dropwise condensation of water or Low surface tension solvents. Depending on the desired function, microstructured or nanostructured silicon substrates are covered with oil-based or water-based or ionic liquids or perfluoroalkylated silanes, resulting in superhydrophobic surfaces which allow the condensate to drop without the impregnating agent being washed out or replaced by the condensate.

By structuring a base material with low surface energy in combination with an impregnation, it is also possible to produce surfaces with omniphobic properties, which are additionally distinguished by a very low adhesion of droplets to the surface. T.-S. Wong et al. describe in their publication the coating of photolithographically produced nanostructured surfaces with impregnating agents in order to make them omniphobic. It is reported by "Lubricant-Infused Surfaces" (LIS) or "Slippery Lubricant Infused Porous Surfaces" (SLIPS), which show an improved drop condensation. (T.-S. Wong et al., "Bioinspired self-repairing slippery surfaces with pressure-stable omniphobicity", Nature, Vol. 477, No. 7365, pp. 443-447, 201 1; see also JD Smith et al., "Droplet mobility on lubricant-impregnated surfaces ", Soft Matter, Vol. 9, No. 6, pp. 1772-1780, 2013. and K.-C. Park et al.," Condensation on slippery asymmetric bumps ", Nature, Vol. 531, No. 7592, pp. 78-82, 2016).

US Pat. No. 9,121,307 B2 likewise discloses a method for producing SLIPS. This metal, glass or polymer substrates are used, the surface of which are rough or porous designed by means of attachment of fibers or particles or electrochemical deposition of polymers. The sequential deposition of nanoparticles or microparticles on the substrates also leads to sufficiently structured surfaces. In addition, the surface thus structured is chemically functionalized with, for example, a perfluorocarbon oil and then covered with a hydrophobic lubricant consisting of liquids which have a high affinity to the underlying surface in order to immobilize the lubricant. Depending on the nature of the impregnating agent, the surfaces produced in this way have high phobicity against various types of gases and liquids.

WO 2012 100 099 A2 likewise discloses the representation of SLIPS, wherein an impregnating agent is applied to a rough surface of a substrate, penetrating into and simultaneously covering it. In the process, a liquid outer layer or film is formed on the surface, which is immobilized by the substrate and forms, for example, a repellent surface.

The material of the substrate is preferably porous and may be a polymer, metal, gemstone, glass, carbon or a ceramic. This rough surface is over for example Etching processes or growth of structures generated The rough surface can have a hierarchical structure with micro- and nanoscale structures.

In particular, perfluorinated liquids are disclosed as impregnating agents. It is important that the rough surface and the applied impregnating agent are of the same chemical nature. It would even be optimal if both the surface and the impregnating agent have the same functional groups. To enable this compatibility, the surfaces of the porous material are first modified. For example, it describes how the OH groups of the surfaces can be functionalized with perfluorosilanes.

In addition to smooth omniphobic surfaces with fully fluorinated coatings, the impregnation of nanostructured surfaces with fluorine-containing impregnating agents represents an attractive procedure for efficient droplet condensation of fluids with a surface tension of <20 mN / m.

Disadvantageously, these coating methods could only be used on regular substrates. Complex components such as the surface of a heat exchanger can not be functionalized in this way.

From US Pat. No. 2,919,115 A, impregnated porous condenser surfaces are known which enable efficient dropwise condensation. For this purpose, metal substrates are first subjected to a wet-chemical etching and pickling process in order to make the surface porous. Subsequent incubation of the component in a hydrophobic impregnating agent, such as oleic acid, results in a hydrophobic coating which adheres well to the substrate due to the porosity of the surface. At the same time, the pores form a kind of reservoir for the impregnating agent, so that it can be repeatedly transported by capillary forces to the surface of the substrate in order to replace any impregnating agent which has been removed with the water vapor. This ensures a constant hydrophobicity of the surface. Disadvantageously, the etching and pickling process is carried out using chromosulfuric acid, a process technology extremely problematic chemical.

In MOFs, the metal ions can be multi-dimensionally linked via organic linker molecules. In turn, these linker molecules may have multiple coordinating functional groups (S. Bauer and N. Stock, "MOFs-Metal Organic Scaffolds, Functional Porous Materials," Chemistry in Our Time, Vol. 42, No. 1, pp. 12-19, 2008). Due to the coordinative bonding and the organic molecules in the structure, MOFs tend to have moderate surface energies, but modifying the linkers, such as the introduction of ring substituents in aromatic systems, allows the physicochemical properties of MOF to be adapted to individual applications ( TK Maji and S. Kitagawa, Chemistry of porous coordination polymers, Pure Appl. Chem., Vol. 79, No. 12, pp. 2155-2177, 2007).

With regard to hydrophobic surface coatings, only MOF powders or MOF coatings on glass with hydrophobic or superhydrophobic properties have hitherto been known from the literature. To describe z. B. Meng et al. the preparation of superhydrophobic and thus superoleophilic surfaces by impregnation of glass surfaces to which MOF powder particles have been dip coated with stearic acid and a perfluoroalkylsilane (Meng W., Z. Feng, F. Li, T. Li, and W. Cao) Porous coordination polymer coatings fabricated from Cu3 (BTC) 2-3H20 with excellent superhydrophobic and superoleophilic properties ", New J. Chem., Vol. 40, No. 12, pp. 10554-10559, 2016).

Other publications are devoted to the hydrophobization of MOF powders, such as T.-H. Chen, I. Popov, O. Zenasni, O. Daugulis, and OS Miljanic, "Superhydrophobic perfluorinated metalorganic frameworks", Chem. Commun., Vol. 49, No. 61, pp. 6846-6848, 2013 or JG Nguyen and SM Cohen, "Moisture-resistant and superhydrophobic metal-organic frameworks via postsynthetic modification", J. Am. Chem. Soc., Vol. 132, No. 13, pp. 4560-4561, 2010.

The (super) hydrophobic properties of the MOF powders are achieved by pre- or postsynthetic functionalization of the linker molecules or impregnation. For coatings, the hydrophobicity is additionally promoted by size differences of microfluidic MOF particles. Compared to liquids with low surface tension (eg conventional refrigerants and solvents), however, previous (super) hydrophobic MOF coatings are not repellent, but even complete wetting occurs. The surfaces would be "flooded" by the condensate in the condensation by nucleation within the porous surface structures and it would come to film condensation.

In the case of lubricant-impregnated surfaces (LIS), on the other hand, droplet condensation of fluids with low surface tension is possible. However, these have so far been only complicated, z. B. photolithographic nanostructuring processes. In the known LIS is also working with a hydrophobic functionalization of the base material. Disadvantageously, the coatings applied in this way have low mechanical stability. The lubricants are partially removed from the photolithographically structured surface again by the condensing liquids or washed out. Moreover, coating processes for complex components are not possible with these processes. The object of the invention is to provide a simple process for the production of stable, omniphobic surface coatings which, inter alia, enable efficient dropwise condensation of organic and / or anhydrous fluids with a low surface tension.

The object is achieved by a method for coating components with an omniphobic surface coating, containing at least one organometallic skeleton compound and an impregnating agent, with the steps

Electrochemical deposition of the organometallic framework compound on the component by means of electrolysis, of an electrolyte solution containing at least one metal ion, at least one linker compound and a solvent,

Application of an impregnating agent to the organometallic skeleton compound wherein the metal ion

i) is dissolved as metal ion salt in the electrolyte solution

and or

ii) is generated by electrolytic oxidation or reduction of a contained in the component and / or electrode metal ion precursor at the interface between the component and the electrolyte solution and / or provided in the electrolyte solution and wherein the component a) is simultaneously electrode

or

b) is introduced into an electric field between at least two electrodes, wherein the linker compound is an organic, at least monodentate compound, wherein the impregnating agent has a low surface tension of <30 mN / m.

The preparation of the omniphobic surface coating on the component is carried out according to the invention by electrochemical deposition of a layer of at least one organometallic (framework) compound and subsequent application of an impregnating agent.

According to the invention, in the first step, the electrochemical deposition of the organometallic (framework) compound takes place on the surface of the component.

In this case, at least one constituent of the MOF coating (linker compound and / or metal ion) must be formed at the interface between the component and the electrolyte solution in order to initiate the coating process. In one embodiment, the electrochemical deposition takes place potentiostatically, galvanostatically and / or with current and / or voltage pulses. Potentiostatic and galvanostatic process control are preferred for homogeneous coatings. Pulsed process control is preferably used for structured coatings in which spacings of several microns are produced between coated areas.

For this purpose, the component is either immersed in an electrolyte solution and / or filled with an electrolyte solution.

According to the invention, the electrolyte solution contains at least one linker compound and a solvent.

Organometallic framework compounds are formed from metal ions and organic molecules (linker compounds) which act as connecting elements between the metal ions which form nodes. The linker compounds enter into coordinative bonds with the metal ion and one-, two- and three-dimensional networks can be formed.

According to the invention, the linker compound is an at least monodentate organic compound or a mixture of several of these compounds.

The term "at least monodentate" organic compound refers to an organic compound containing at least one functional group capable of forming at least one coordinate bond with a given metal ion.

For the purposes of the invention, complex compounds are also referred to as organometallic framework compounds in which the organic linker molecules contain only one functional group which is capable of coordinating with a metal ion or which coordinate with only one functional group on the metal ion. A scaffold can nevertheless arise because two linker molecules can be linked to one another, for example by hydrogen bonding. These two monodentate linkers then form a coordination unit, which in effect works like a bidentate linker compound.

In one embodiment, the organic, at least monodentate compound contains at least one functional group selected from carboxylate groups, sulfonate groups, phosphonate groups, imidazolate groups, pyridine groups, phenanthroline groups, triazolate groups and / or tetrazolate groups.

In one embodiment, the linker compound is an imidazolate.

In one embodiment, the linker compound is selected from 1 .4-Benzene dicarboxylates (BDC)

Tetramethyl-1,4-benzene dicarboxylate (TBDC)

2-amino-1,4-benzene dicarboxylates (NH 2 -BDC)

1, 3,5-benzenetricarboxylates (BTC)

2,6-naphthalenedicarboxylates (NDC)

Biphenyl-3,4 ^' , 5-tricarboxylates (BPT)

2 ^{^{'-fluoro-biphenyl-3,4'}} -5-tricarboxylates

Benzen-2,5-dihydroxy-1,4-dicarboxylates (dhbcd)

2.5-dimethoxy-1,4-benzene dicarboxylate (DMBDC) benzene hexacarboxylate (BHC)

Furan-2,5-dicarboxylates (fdc)

Pyridine-2,6-dicarboxylates (pda, dpa)

4-hydroxyquinoline-2-carboxylates (qc)

2,2 ^{^{'-Biquinoline-4,4'}} -dicarboxylaten (bqdc)

3-hydroxypyrazine-2-carboxylates (hpzc)

2,3-pyrazinedicarboxylates (pza)

imidazole-4,5-dicarboxylates (IDC)

4,5-imidazoledicarboxylates (imidc)

2-Propyl-1H-imidazole-4,5-dicarboxylates (Hpimda)

4- (1H-tetrazol-5-yl) -biphenyl-3-carboxylates (tbca) thiophene-2,5-dicarboxylates (TDC, TDA)

9,9-dimethylfluorene-2,7-dicarboxylates (MFDA)

Polychlorotriphenylmethyltricarboxylate radicals (PTMTC)

1: 5-naphthalenedisulfonates (1, 5-NDS)

2.6- Naphtalene disulfonates (2,6-NDS)

Anthraquinone-2,6-disulfonates (AQDS) 4,4 ^{'-Oxybenzoaten} (OBA)

3,5-disulfobenzoates (dsb)

4 _! 4 ^' _! 4 ^" -S-triazines-2 _: 4,6-triyl-tribenzoates (TATB)

1, 3,5-Benzene tris benzoate (BTB)

4,4 ^{'-Biphenyldicarboxylsäuren} (BPDC)

Cis-1, 3,5-cyclohexanetricarboxylic acids (CTC)

Pyrazine dicarboxylic acids (h pzdc)

1, 1 ^{'-Phenanthroline-2,9-dicarboxylic} acids (H2P enDCA)

2,5-pyridinedicarboxylic acids (h pydc)

4,5-imidazoledicarboxylic acids (HsImDC)

4 _! 4 ^{_{'-Bipyridine-2!}} 2 ^' _! 6,6 ^{'-tetracarboxylsäuren} (H ₄ BPTCA)

4,4 ^' - (hexafluoroisopropylidenes) bis (benzoic acids) (H2 fipbb)

4,4 - [(2,5-dimethoxy-1,4-phenylene) -di-2,1-tethenediyl] bisbenzoic acid (H2pvdc)

(Carboxymethyl) iminodi (methylphosphonic acids) (h cmp)

2-aminoterephthalic acids (H2ATPT)

Etidronic acids (H ₅ edp)

2- (carboxylic acid) -6- (2-benzimidazolyl) pyridines (Hcbmp)

Phosphonoacetic acids (H3PPA)

Tris (4-carboxyphenyl) phosphine oxides (H3TPO)

Tris (benzimidazol-2-ylmethyl) amines (ntb)

1, 4-phenylenediacetates (pda)

1,1,1 ^' , 1 ^" - (2,4,6) -trimethylbenzene-1,3,5-triyl) tris (methylene) tripyridinium-4-oleate (TTP)

1, 1 ^' phenanthrolines (phen)

1,3-Benzenditetrazol-5-ylene (m-BDTH)

5- (pyridin-4-yl) isophthalates (PIA)

5-tert-butyl-isophthalates (tip) Methyl isophthalates (mip) Imidazolates (Im) 1, 2,3-Triazolaten (Tz) 4,4 ^' -Bipyridines (bipy) 1, 2,3-Triazolato [4,5-b] pyridines (tpy) Tricarboxylato-triphenylamines (tca Adipates (ad)

2-Fluoro-4- (1 H-tetrazol-5-yl) benzoates (FTZB) 4,4 ^', 4 ^"- (Benzentricarbonyltris- (azanediyl)) tribenzoates (BTATB) 1, ^1', ^1" - (benzene- 1, 3,5-triyl) tripiperidine-4-carboxylates (BTPCA) 1, 10-bis (4-carboxybenzyl) -4,40-bipyridines (BPYBC) glutarates (glu) succinates (succ) isonicotinates (Ina) fumarates (fma )

In one embodiment, the linker compound is formed during the electrolysis of at least one linker precursor compound.

For the purposes of the invention, a linker precursor compound is a compound from which the corresponding linker compound is generated in situ by electrochemical reaction and / or chemical reaction as a result of an electrochemical reaction. This can be done for example by electrolytic or electrolytically induced substitution, addition, reduction, cleavage, ring closure reaction, ring-opening reaction, deprotonation, proton transfer and / or radical reaction.

In one embodiment, the linker precursor compound is selected from the free acids or anhydrides of the linker compound. The linker precursor compounds for the linker compounds imidazolates, triazolates and tetrazolates are each their corresponding imidazoles, triazoles or tetrazoles.

In one embodiment, the total concentration of the linker compound and / or linker precursor compound in the electrolytic solution is from 0.001 mol / l to 2.500 mol / l, preferably from 0.01 mol / l to 1.5 mol / l, particularly preferably from 0.01 mol / l to 0 , 5 mol / l. In one embodiment, the electrochemical reaction of at least one component of the electrolyte solution during the electrolysis triggers the chemical reaction to form the linker compound from the linker precursor compound.

Component of the electrolyte solution are, for example, metal ion salt, conductive salt, solvent and / or structure-directing additive.

For example, by the cathodic reduction of a nitrate salt in the electrolyte solution, in which hydroxide ions are formed, the pH can change so much that z. As acid groups are deprotonated and, for example, arise from the free carboxylic acids, the linker carboxylates.

In one embodiment, the deprotonation of acid or imidazole groups takes place by changing the pH, for example by water decomposition during the electrolysis.

According to the invention, the electrolyte solution contains at least one solvent. According to the invention, the term solvent comprises pure solvents which comprise only one solvent component and also solvent mixtures, that is to say mixtures of at least two solvent components.

In principle, all solvents and / or all solvent mixtures in which the starting materials used in the process can be dissolved under the chosen reaction conditions, such as pressure and temperature, are conceivable as solvents.

In one embodiment, the solvent is selected from water; Alcohols, carboxylic acids, nitriles, ketones, halogenated alkanes, acid amides, amines, sulfoxides, pyridine, N-formylamides, N-acylamides, aliphatic ethers and / or cyclic ethers and / or mixtures thereof.

In one embodiment, solvent molecules simultaneously function as linker precursor compounds.

In one embodiment, the electrolyte solution additionally contains a conductive salt and / or structure-directing additive.

Conducting salt or conductive additive refers to compounds which increase the conductivity of the electrolyte solution in order to influence the homogeneity of the electrodeposited coating. By increasing the conductivity of the electrolyte solution, the ohmic resistance is lowered during the deposition, which results in the electric field being more homogeneous. This leads to a more uniform (spatial) distribution of the dissolution stream and thus to a deposited coating, which is more uniformly structured, especially with regard to the layer thickness. For the purposes of the invention, a conductive salt is understood as meaning a mixture of a plurality of conductive salts.

In one embodiment, the conductive salt is selected from organic and / or inorganic salts.

In one embodiment, the organic salt is selected from organic sulfates, sulfonates, borates, phosphates, phosphonates, carboxylates and / or ammonium salts. In one embodiment, the ammonium salts are selected from ammonium surfactant salts.

Ammonium surfactant in the context of the invention are salts containing quaternary ammonium ions NR ₄ ⁺ , wherein R is selected from H and / or AI alkyl, wherein all R may be the same or different and wherein at least one radical R contains at least 2 C-atoms.

In one embodiment, the ammonium salts are selected from ammonium surfactant methylsulfates, preferably methyltributylammonium methylsulfate, ammonium hydroxides, preferably tetrabutylammonium hydroxide, ammonium surfactant tetrafluoroborates, preferably tetrabutylammonium tetrafluoroborate and ammonium surfactant hexafluorophosphates, preferably tetrabutylammonium hexafluorophosphate.

In one embodiment, the carboxylates are selected from acetates and / or oxalates.

In one embodiment, the inorganic salt is selected from nitrates, nitrites, sulfates, sulfites, disulfites, sulfides, carbonates, bicarbonates, phosphates, hydrogen phosphates, dihydrogen phosphates, pyrophosphates, chromates, cyanogen salts, hydroxides, chlorides, perchlorates, chlorates, bromides, bromates, tetrafluoroborates , iodides, iodates and / or fluorides, preferably nitrates and / or sulfates.

In one embodiment, the concentration of the conductive salt in the electrolytic solution is 0.01 mol / l to 2.00 mol / l, preferably 0.05 mol / l to 0.5 mol / l.

In one embodiment, the electrolyte solution additionally contains a structure-directing additive.

Structurally-conducting additives are compounds which temporarily or permanently cause or direct structuring of a compound in a specific spatial manner. Temporally means that the directing molecule is not incorporated into the structure and this z. B. by washing with a solvent after the reaction leaves again but the structure formed is maintained. Unlimited in time means that the directing molecule either becomes part of the new structure or else remains as an independent molecule in the structure, for. B. in a pore, in a porous material.

For the purposes of the invention, a structure-directing additive is also understood to mean a mixture of several structure-directing additives.

In one embodiment, the structure-directing additives are selected from anionic, cationic and / or neutral surfactants.

In one embodiment, the structure-directing additives are selected from imidazoles, pyridines, acetates, oxalates, citrates, lauryl sulfates, organic ammonium salts, preferably from imidazoles and ammonium salts.

According to the invention, the electrolyte solution contains at least one metal ion.

For the purposes of the invention, this is the metal ion necessary for the synthesis of the organometallic skeleton compound or a mixture of several different metal ions.

In one embodiment, the at least one metal ion for synthesis of the organometallic framework compound is selected from Cu ⁺ , Cu ²⁺ , Fe ²⁺ , Fe ³⁺ , Co ²⁺ , Co ³⁺ , Al ³⁺ , Mg ²⁺ , Ti ⁴⁺ , Ti ³⁺ , Zr ⁴ *, Mn ³⁺ , Mn ⁴⁺ , Cr ³ ", V ²⁺ , V ³⁺ , V ⁴⁺ , Mo ³⁺ , W ³⁺ , Ni ²⁺ , ΝΓ, Ag ⁺ , Au ⁺ , Sn ²⁺ , Sn ⁴⁺ , Si ²⁺ , Si ⁴⁺ , Pb ²⁺ , Pb ⁴⁺ and / or Zn ²⁺ , preferably Cu ²⁺ , Fe ²⁺ , Fe ³⁺ , Al ³⁺ and / or Zn ²⁺ .

According to the invention, the at least one metal ion is dissolved either i) as the metal ion salt in the electrolytic solution

and or

ii) generated by electrolytic oxidation or reduction of a metal ion precursor contained in the component and / or electrode at the interface between the component and the electrolyte solution and / or provided in the electrolyte solution.

Metal ion precursor, or metal ion precursor compound, denotes the compound in which the metal ion necessary for the synthesis of the organometallic skeleton compound, in particular chemically bonded, is present. The metal ion precursor therefore contains the metal ion necessary for the synthesis of the organometallic skeleton compound in-in particular chemically-bonded form, which does not yet have the oxidation state necessary for the synthesis of the MOF. By oxidation or reduction of this metal ion precursor or the metal ion precursor compound in the electrolysis, the metal ion is provided in the electrolytic solution.

The metal ion precursor according to the invention is contained in the component and / or electrode. If, for example, one wishes to produce a MOF coating with Mn ²⁺ as metal ion, the component and / or the electrode may contain manganese as metal or manganese oxide (eg MnO 2 or ηη 3θ ₄ ) as metal ion precursor.

Metallic manganese is then oxidized (anodically) to produce Mn ²⁺ in the electrolyte solution; Manganese oxides such as MnÜ2 or Mn30 ₄ would be reduced (cathodically) (Mn ⁴⁺ to Mn ²⁺ and Mn ³⁺ to Mn ^2+, respectively).

According to the invention, the at least one metal ion in variant i) is dissolved in the electrolyte solution as metal ion salt. The metal ion then already has the necessary for the synthesis of MOF oxidation state.

Then, the linker compound is electrolytically or electrochemically induced from a linker precursor compound at the interface between the device and the electrode.

Then, the linker compound in the electrolyte solution is generated in-situ from the corresponding linker precursor compound (s) at the interface between the component and electrolyte solution by electrochemical reaction and / or chemical reaction as a result of an electrochemical reaction.

The at least one metal ion may be an electrolyte component present in the form of a corresponding metal ion salt, that is to say may be present dissolved in the electrolyte solution. Then the metal ion already has the oxidation state necessary for the synthesis of the MOF.

In one embodiment, a metal salt containing a metal ion in the oxidation state necessary for the synthesis of the MOF is dissolved directly in the electrolyte solution.

In one embodiment, the concentration of the metal ion salt or a mixture of a plurality of metal ion salts in the electrolytic solution is 0.005 mol / l to 1 mol / l, preferably 0.05 mol / l to 0.1 mol / l.

In one embodiment, at least one metal ion salt and at least one linker precursor compound in the electrolyte solution are initially introduced for coating the component

In one embodiment, the metal ion in the electrolytic solution is generated by reacting metal ion precursors contained in at least one of the non-constituent electrodes electrolytically induced to the metal ion and providing them in the electrolytic solution. The metal ion is then also present in the necessary for the synthesis of MOF oxidation state in the electrolyte solution.

Even then, the linker compound in the electrolyte solution by in situ from the / the electrochemical reaction and / or chemical reaction as a result of an electrochemical reaction corresponding linker precursor compound (s) are generated at the interface between the component and the electrolyte solution.

Thus, at least one component of the MOF coating (metal ion or linker compound) must be formed at the interface between the component and the electrolyte solution to ensure the coating process. This formation of the constituent is triggered electrolytically or electrochemically.

That is, either at the interface between the device and the electrolyte solution, the MOF metal ion is electrolytically generated from a metal ion precursor and / or the linker compound is formed at the interface by electrolysis from a linker precursor compound.

The formation of the MOF thus takes place in each case due to an electrochemical reaction on the component or chemical reaction as a result of an electrochemical reaction on the component. The electrochemical reaction is triggered and controlled by applying an electric field to the device (device connected as an electrode) or placing the device in an electric field (device not connected as an electrode).

In one embodiment, metal ions and linker compounds present in the electrolytic solution already form MOF crystal building units (ie, smaller particles) in the solution, some of which are integrated into the growing coating at the interface. However, a metal ion precursor and / or a linker precursor compound must still be available to the system.

According to the invention, according to variant ii), the at least one metal ion is generated by electrolytic oxidation or reduction of a metal ion precursor contained in the component and / or electrode at the interface between the component and the electrolyte solution.

According to the invention, the component is either a) simultaneously electrode or b) is introduced into an electric field between two electrodes.

In variant a), the component is simultaneously electrode. This means that at least one of the electrodes required for the electrolysis is then represented by the component.

In one embodiment, the component is simultaneously metal ion precursor-containing electrode and the metal ion comes directly from the surface of the component to be coated.

In one embodiment, the device includes at least one metal ion precursor-containing material selected from pure metal and / or metal alloys, such as brass, bronzes, german silver, steels, inconel, hastelloy, monel, titanium alloy, duralumin, etc., and / or metal compounds, for example Metal oxides and / or hydroxides. In one embodiment, the metal is preferably selected from Cu, Fe, Al and / or Zn.

In one embodiment, the metal oxides and / or hydroxides are preferably selected from Cu ₂ O, CuO, Fe ₂ O ₃ , Fe ₃ O ₄ , Al 2 O 3, Al (OH) ₃ and / or ZnO.

In one embodiment, the component comprises an electrically conductive carrier material and a coating containing a metal ion precursor, wherein this coating is selected from metals and / or metal alloys and / or metal oxides and / or hydroxides.

In one embodiment, the metal ion precursor-containing coating is a coating containing metal, wherein the metal is selected from Cu, Fe, Co, Al, Mg, Ti, Zr, Mn, Cr, V, Mo, W, Ni, Ag, Au, Sn , Si, Pb and / or Zn, preferably Cu, Fe, Al and / or Zn.

In one embodiment, the metal ion precursor-containing coating is a coating containing metal oxides and / or hydroxides selected, for example, from US Pat. B. from Al2O3, (Al (OH) ₃ , Cu ₂ 0, CuO, Cu (OH) ₂ , Fe ₃ 0 ₄ , Fe ₂ 0 ₃ , FeO (OH) Co ₃ 0 ₄ , CoOOH, Co (OH). ₃ , CoO, Ti ₂ 0 _3, Ti (OH) _2, Ti (OH) _3, Ti (OH) _4, Ti0 _2, MnO (OH), MnO (OH) _2, Mn ₃ 0 _4, Mn ₂ 0 _3, MnO ₂ , Cr ₂ O ₃ , Cr (OH) ₃ , Cr (OH) ₄ , CrO ₂ , CrO ₃ , VO ₂ , V ₂ 0 ₃ , V ₂ 0 ₄ , V ₂ 0 ₅ , MoO ₂ , MoO ₃ , Ni ₃ 0 ₄ , Ni ₂ 0 ₃ , NiO, (NiOH) ₂ , AgOH, Ag ₂ 0, Ag ₂ 0 ₃ , Si0 ₂ , Pb (OH) ₂ , Pb (OH) ₄ , Pb ₃ 0 ₄ , Pb0 ₂ and / or ZnO, Zn (OH) ₂ , as well as their mixtures or other mixed compounds with other ions such as S0 ₄ ^{2 "} , S0 ₃ ^2" , etc. (eg verdigris) preferably Al ₂ O ₃ , Cu ₂ O, CuO, Fe ₂ 0 ₃ , Fe ₃ 0 ₄ and / or ZnO.

In one embodiment, the metal ion-containing coating is a coating containing a metal alloy. In one embodiment, the metal alloy is selected from brass, bronzes, german silver, steels, inconel, hastelloy, monel, titanium alloy, and / or duralumin.

In one embodiment, the carrier material is selected from electrically conductive polymers, carbons, such as. As graphite, carbon fibers, carbon nanotubes or other carbon allotropes.

In one embodiment, the support material is provided with a coating containing a metal ion precursor.

According to the invention, the metal ion can be generated electrolytically by oxidation or reduction of a metal ion precursor contained in the component at the interface between the component and the electrolyte solution, wherein the component is connected as an electrode.

In one embodiment, the component is connected during the electrochemical deposition as a metal ion generating electrode. In one embodiment, the device is connected as an anode during the electrochemical deposition. The metal ion precursor or metal ion precursor compound contained in the component is then oxidized anodically and the metal ion passes into the electrolyte solution. By the reaction with the linker compound also present in the electrolytic solution, the formation and electrochemical deposition of the organometallic skeleton compound takes place on the component.

In electrochemical deposition, where the device functions as a metal ion-generating anode, the device contains metal ion precursors of lower oxidation state than the metal ion of the resulting organometallic framework compound.

In the electrochemical deposition, in which the component acts as an anode, the component is connected as an anode. By applying a voltage, metal ion precursors contained in the surface or uppermost layer of the component to be coated are anodically oxidized and the electrolyte solution is thus supplied with the metal ion on the component. There, the metal ion reacts with the linker compound contained in the electrolyte solution to the organometallic skeleton compound, which is deposited on the component.

In one embodiment, the voltage during the electrochemical deposition in variant a) is 0.2 to 40 V, or -10 to 10 V relative to a mercury sulfate reference electrode, preferably -2.5 to 1 V with respect to a mercury / mercury sulfate reference electrode.

The deposition of the MOF is operated until the layer thickness of the MOF 0.1 to 1000 μηι, preferably 1 to 100 μηι, more preferably 2 to 20 μηι, in particular 3 to 10 μηη.

The determination of the layer thickness is carried out by means of scanning electron microscopy and light microscopy.

The duration of the electrolysis is 30 s to 5 h, preferably 5 min to 60 min, particularly preferably 10 to 30 min.

In one embodiment, the device is switched as a cathode during electrochemical deposition.

In the case of electrochemical deposition, in which the component functions as a metal ion-generating cathode, the component contains metal ion precursors with a higher oxidation state than the metal ion of the resulting organometallic framework compound.

In the electrochemical deposition, in which the component acts as a metal ion-generating cathode, the component is connected as a cathode. By applying a voltage, the metal ion precursor contained in the surface or uppermost layer of the component to be coated is cathodically reduced, and thus the electrolyte of the metal ion on the component fed. There, the metal ion reacts with the linker compound contained in the electrolyte solution to the organometallic skeleton compound, which is deposited on the component.

It is also possible that the metal ion precursor compound is present, for example, not as a component metal or component coating but as metal ion salt dissolved in the electrolyte solution. The metal ion then does not have the necessary oxidation state for the synthesis of the MOF, which is why the metal ion salt is first electrochemically reacted and the necessary for the MOF synthesis, metal ion is formed.

As an example, z. For example, permanganate salts such as KMn0 ₄ in question, which are then reduced to the component electrochemically Mn ²⁺ ions.

As already described above, in one embodiment, the linker compound is generated from a linker precursor compound contained in the electrolytic solution.

In one embodiment, the linker compound is formed during the electrolysis of at least one linker precursor compound. This can be done by electrochemical reaction and / or chemical reaction as a result of an electrochemical reaction.

In one embodiment, the electrochemical reaction of the electrolyte initiates the chemical reaction to form the linker compound from the linker precursor compound. For example, by the cathodic reduction of a nitrate salt in the electrolyte solution, in which hydroxide ions are formed, the pH can change so much that z. As acid groups are deprotonated and, for example, arise from the free carboxylic acids, the linker carboxylates.

In one embodiment, the device acts as a linker-generating electrode.

In one embodiment, the device acts as a linker-generating cathode.

In that case, the component is made of any electrically conductive material and the metal ions originate from the metal ion precursor-connected electrode and / or from the metal ion salt dissolved in the electrolyte solution.

In one embodiment, however, the component also contains a linker-generating cathode with a metal ion precursor having a higher oxidation state than the metal ion of the metal-organic framework compound to be formed. In electrochemical deposition, where the device acts as a linker-generating cathode, the linker precursor compound contained in the electrolyte solution is electrochemically or chemically reacted to the corresponding linker compound on the device as a result of an electrochemical reaction. This is done for example by cleavage of the precursor compound or by deprotonation as a result of a pH change by hydrogen-proton-consuming reduction. The pH change can also be done by hydroxide ion-generating reduction of solvent or Leitsalzbestandteilen, such as water and / or nitrate ions.

By applying a voltage so the linker connection of the electrolyte solution is supplied to the component. There, the linker compound reacts with the metal ion contained in the solution to organometallic skeleton compound, which is deposited on the component.

In one embodiment, the component acts as a linker-generating anode. The component then consists of any electrically conductive material or the component contains metal ion precursors having a lower oxidation state than the metal ion of the organometallic framework compound.

In electrochemical deposition, where the device acts as a linker-generating anode, the linker precursor compound contained in the electrolytic solution is electrochemically or chemically reacted to the corresponding linker compound on the device as a result of an electrochemical reaction. This is done, for example, by oxidation of the linker precursor compound, e.g. B. an aldehyde functionality to the corresponding carboxylic acid functionality. It may also be a cleavage of the linker precursor compound, such as the acidic cleavage of protecting groups of protected carboxylic acid groups.

However, the reaction of the linker precursor compound to form the linker compound can also be effected by a pH change by an electrolytic oxidation consuming hydroxide ions or by the oxidation of solvents such as water or conductive salt constituents which generates hydrogen ions.

During electrolysis, the linker compound is added to the electrolyte solution on the component. There, the linker compound reacts with the metal ion contained in the electrolytic solution to organometallic skeleton compound, which is deposited on the component. The metal ion can be in the form of a metal salt electrolyte component and / or the metal ions originate from the cathode connected metal ion precursor containing electrode and / or the metal ion is also on the component containing a metal ion precursor with a lower oxidation state than the metal ion of the organometallic skeleton by anodic reaction fed to the electrolyte solution. The electrodes may also be different from the component. This corresponds to variant b) in the process according to the invention.

According to the invention, the component is introduced into an electric field between two electrodes in variant b).

Then, the electrochemical deposition of the organometallic skeleton compound by means of bipolar electroplating indirectly anodic or indirect cathodic on the component.

In this case, the component is introduced into an electric field generated in the electrolyte solution by at least two electrodes, through which the component is polarized, whereby electrochemical deposition takes place on the component.

The component is then not simultaneously electrode or connected as an electrode.

In this procedure, also referred to as bipolar electroplating, the component is introduced into an electric field between at least one positively polarized and at least one negatively polarized electrode.

In one embodiment, the coating space of the component, that is, the area surrounding the component containing the electrolyte solution, is separated from the electrode spaces by membranes to minimize or prevent the conversion of electrolyte components, such as the linker precursor compound, to the electrodes.

According to the invention, in variant ii), the metal ion is generated by electrolytic oxidation or reduction of a metal ion precursor contained in the component and / or electrode at the interface between the component and the electrolyte solution and / or provided in the electrolyte solution

In one embodiment, the metal ion necessary for synthesizing the organometallic skeleton compound is released from the component due to the polarization by the electric field between the at least two electrodes, wherein the metal ion dissolves from the component by electrochemical oxidation or reduction and passes into the electrolyte solution. There it reacts with the linker compound contained in the solution and is deposited as organometallic framework compound on the component. One then speaks of indirect anodic or indirect cathodic deposition.

In one embodiment, the component contains metal ion precursors selected from pure metal and / or metal alloys and / or metal oxides and / or hydroxides, as also described above for a component as a metal ion-providing electrode. In one embodiment, the component comprises an electrically conductive carrier material and a coating containing metal ions, wherein this coating is selected from metals and / or metal alloys and / or metal oxides and / or hydroxides, as described above for a component as a metal ion-providing electrode ,

In one embodiment, the support material of the component is selected from electrically conductive polymers, carbons, carbon fibers and materials, as already described above for variant a), for a component which is coated with metal ion precursor materials of higher or lower oxidation state.

In one embodiment, the component, in particular its surface, comprises an electrically conductive material, for example metals, metal oxides, semiconductor materials, ITO or FTO glass, conductive polymers. Then, at the interface between the device and the electrolyte solution, the linker precursor compound is electrolytically or electrochemically reacted to the linker compound.

The electric field between the electrodes must be strong enough for the indirect forms of deposition.

In one embodiment, the voltage during the electrochemical deposition in variant b) is 1 to 100 volts, preferably 5 to 20 V.

The organometallic framework compounds are deposited as a uniformly thick layer on the component. After deposition, the coated component is rinsed with water or a solvent and dried if necessary.

In one embodiment, the metal ions necessary for the synthesis of the MOF coating from one of the electrodes (corresponding to variant b - the component is not electrode) are provided by oxidation or reduction in the electrolyte solution (variant ii).

According to the invention, according to variant i), the metal ion is dissolved as metal ion salt in the electrolyte solution

and / or according to variant ii)

generated by electrolytic oxidation or reduction of a metal ion precursor contained in the component and / or electrode at the interface between the component and the electrolyte solution and / or provided in the electrolyte solution, wherein the component a) is simultaneously electrode or b) is not simultaneously electrode, but in an electric Field is inserted between two electrodes.

The following cases are possible: The at least one metal ion is dissolved in the electrolyte solution as the metal ion salt, preferably in the oxidation state necessary for the synthesis of the MOF, one of the electrodes used for the electrolysis is at the same time a component and the linker compound is generated at the interface of component and electrolyte solution.

The at least one metal ion is generated by electrolytic oxidation or reduction of a metal ion precursor contained in the component at the interface between the component and the electrolyte solution, wherein at least one of the electrodes used for the electrolysis is simultaneously a component.

The at least one metal ion is provided by electrolytic oxidation or reduction of a metal ion precursor contained in an electrode in the electrolyte solution, and the linker compound is electrolytically generated at the interface of the component and the electrolytic solution, wherein at least one of the electrodes used for electrolysis is simultaneously a component.

For the combination of i) and / or ii) with variant b), this means that the component is introduced into an electric field between at least two electrodes and the at least one metal ion is a metal ion salt in the oxidation stage necessary for the synthesis of the MOF in which Electrolytic solution is dissolved and / or is provided by electrolytic oxidation or reduction of a metal ion precursor contained in an electrode in the electrolyte solution and / or is generated and provided by electrolytic oxidation or reduction of the corresponding metal ion precursor containing component at the interface between the component and the electrolyte solution, wherein the component not simultaneously electrode.

In one embodiment, the component is dried after coating with the MOF at a pressure of 1000 mbar to 10-10 mbar and a temperature in the range of -40 ° C to 180 ° C.

In one embodiment, the layer of organometallic framework compounds also contains micropores and / or macropores and / or mesopores also partially with different types of pores, e.g. B. slotted pores.

The term micropores refers to pores with a diameter of up to 2 nm. The term mesopores refers to pores with a diameter of 2 nm to 50 nm. The term macropores refers to pores with a diameter> 50 nm.

The specific surface area (BET) of the organometallic framework compounds prepared according to the invention is determined by DIN ISO 9277.

The specific surface area of the MOF coating produced according to the invention is from 5 m2 / g to 2500 m2 / g. Scanning electron microscopy, however, is a more suitable method (eg, in comparison to physisorption measurements) for investigating the MOF coatings produced according to the invention in order to investigate the porosity / structure and the shape of the porosity. So it is relevant how the pores are designed on the crystallite surface. The determination of the BET surface area by physisorption measurements, however, can be misleading, since a high BET surface area in m2 / g could also be due to pores in the "crystallite interior", while the crystallite surface is relatively smooth.

Scanning electron micrographs show a particularly structured crystallite growth within the MOF coating by the electrochemical deposition. Thus, uniformly arranged MOF crystallites in, for example, octahedral geometry are found in the coating, which produce a microsized surface morphology (FIG. 1) and, on closer inspection of the surface of a single crystallite, also have nano-scale structures. Likewise, compositions of nanocrystallites can form a nanoscale and microscale suprastructure (Figure 4). Thus, MOF morphologies are observed with gaps in the nanoscale range of 10 to 100 nm (see FIG. 2 and FIG. 5). These spaces advantageously have a continuity.

In addition, the crystallites have a structure-related microporosity, so that advantageously a threefold hierarchical structuring of the surface is found.

In one embodiment, the MOF layers produced according to the invention have a threefold hierarchical structuring. For the purposes of the invention, this means that both a structuring of the surface takes place in the micrometer and in the nanometer range and the surface additionally has micropores.

Advantageously, the production of this hierarchical structure of the surface and of the coating base material succeeds in only one process step, whereas hitherto known, mostly photolithographic processes require several complex process steps.

Even without treatment with impregnating agents, the MOF coatings produced according to the invention advantageously have larger water contact angles than, for example, MOF coatings which have been produced by coating with hydrothermally produced MOF.

A further advantage of the MOF produced according to the invention is the high stability of the crystalline framework compounds, which is ensured by the coordinative bonds of linkers and metal ions. The observed micro- and / or nanostructures with an additional microroughness and porosity caused by the micropores are advantageously suitable for ensuring improved adhesion of the subsequently applied impregnating agent

Due to the very high porosity of the surface, it is possible, for example, to infiltrate omniphobic, low-volatility oils, which are absorbed and retained by the morphologically adapted MOF coatings like a sponge.

According to the invention, after the electrochemical deposition of the organometallic framework compound, the application of an impregnating agent with a low surface tension of <30 mN / m onto the MOF coating takes place.

An additional impregnation of the MOF coating advantageously leads to omniphobic properties of the surface of the component.

Omniphob means that the surface is repellent to a variety of polar and nonpolar fluids. Even polar and nonpolar fluids with low surface tensions of> 10 mN / m up to 50 mN / m, preferably up to 30 mN / m have an increased contact angle on these surfaces, so that dropwise condensation is possible. The same applies to fluids with higher surface tension.

To allow droplet formation of low surface tension fluids, a low surface tension modifier of <30 mN / m is applied to the MOF coating.

In one embodiment, the impregnating agent has a lower surface tension than the fluid to be condensed or the mixture of fluids to be condensed.

A prior treatment with perfluorosilanes, as known from the prior art in photolithographically produced microstructures, is advantageously no longer necessary to ensure the desired wetting properties and sufficient adhesion of the impregnating agent on the MOF coating.

In one embodiment, the impregnating agent has a low surface tension of <30 mN / m, preferably <20 mN / m.

In one embodiment, the impregnating agent is selected from perfluorinated oils, fats and / or thickeners.

In one embodiment, the impregnating agent is selected from perfluorinated polymers and / or perfluoroalkyl ethers and / or partially fluorinated and / or polyfluorinated polymers or alkyl ethers. In one embodiment, the impregnating agent is applied by dipping and / or spraying and / or spin-coating and / or spin-coating methods.

In one embodiment, the omniphobic surface coating produced according to the invention has a contact angle of 15 ° when wetted with water and / or 60 ° when wetted with acetone and / or 95 ° when wetted with diiodomethane.

Advantageously, fluids with low surface tensions of> 10 to <30 mN / m on the components coated according to the invention have a contact angle of at least 35 degrees, preferably at least 50 degrees, suitable for dropwise condensation.

Advantageously, the omniphobic surfaces produced according to the invention are mechanically more stable than hitherto known smooth, perfluorinated, omniphobic surfaces.

A further advantage in the combination of the inventive coating of the surface of the component with organometallic framework compounds and their impregnation lies in the improved adhesion of the impregnating agent on the hierarchically structured MOF layer by favorable intermolecular interactions between impregnating agent and MOF. The washing-off of the impregnating agent by the condensate, which is often observed in the prior art, can thereby be reduced. This physical-mechanical effect was detected by ESEM measurements, which were carried out after application of the impregnating agent. As shown in Figs. 9a-c, the impregnating agent layer is not a closed film but is broken in some places because some larger MOF crystals protrude from the impregnating agent layer as peaks. Between these tips, the impregnating agent is held by adhesive forces and mechanical removal, for example by washing, is immediately more difficult.

FIG. 10 shows a cross section of an impregnated MOF surface according to the invention. There is no closed film formation, but individual tips of the MOF crystals protrude from the impregnating agent layer. The impregnating agent is bound by adhesion forces on the MOF surface.

Thus, the adhesion of the impregnating agent is advantageously no longer dependent on the chemical nature of the impregnating agent and MOF surface and a chemical modification of the surface prior to impregnation is no longer necessary.

Advantageously, the individual physicochemical properties of the respective MOF compound can be influenced by the selection of the linker compound. Thus, it can even be adjusted to what extent the contact angle of the condensing fluids is increased by the lubricant, which is probably due to improved interaction of the linker molecules with the lubricant. The combination of imidazolate-based MOF and perfluoroalkyl ether-based impregnating agent has proven particularly advantageous. The surface energy of the MOF with imidazolate linker is still significantly lower than that of the carboxylate MOF, which can lead to a particularly good adhesion of the impregnating agent on the MOF coating.

Advantageously, with the method according to the invention, even complex components or components can be provided on an industrial scale with an omniphobic surface coating.

Another advantage of the method according to the invention lies in the short duration of the production of an omniphobic surface coating on components.

The invention also provides an omniphobic surface coating comprising an organometallic framework compound and an impregnating agent, the organometallic framework compound containing micropores and / or meso- and / or macropores and / or channels, the organometallic framework compound having a pore volume of 0.002 cm 3 / g to 3,500 cm3 / g, preferably 0.010 cm3 / g to 0.080 cm3 / g, wherein the metal-organic framework compound has a specific surface area of 5 m2 / g to 2500 m2 / g, preferably 50 m ² / g to 1500 m ² / g wherein the layer thickness of the surface coating 0.1 μηη to 1000 μηι, preferably 2 μηη to 100 μηι, more preferably 2 to 10 μηη, wherein the impregnating agent has a surface tension of <30 mN / m, preferably <20 mN / m.

The invention also relates to the use of an omniphobic surface coating according to the invention on components for droplet condensation of fluids having a surface tension of <75 mN / m, preferably <50 mN / m, more preferably <30 mN / m.

In one embodiment, the fluids are selected from organic solvents and / or refrigerants and / or mixtures thereof.

In one embodiment, the fluids are selected from alcohols, ketones, aromatic and / or aliphatic hydrocarbons, halogenated hydrocarbons and / or inorganic fluids.

The invention also provides the use of an omniphobic surface coating according to the invention in heat exchangers.

In one embodiment, the heat exchangers are selected from recuperative heat exchangers, for example shell and tube heat exchangers, plate heat exchangers and spiral heat exchangers.

The heat-transferring surfaces of the heat exchanger are coated on one or both sides. The invention also provides a heat exchanger comprising an omniphobic surface coating, produced by a method according to the invention.

In one embodiment, the heat exchanger is selected from shell-and-tube heat exchangers, plate heat exchangers and / or spiral heat exchangers.

For the realization of the invention, it is also expedient to combine the above-described embodiments according to the invention, embodiments and features of the claims in an expedient manner.

The following exemplary embodiments are intended to explain the invention in more detail, without, however, limiting it to:

The pictures show:

1 shows a scanning electron micrograph of the copper trimesate MOF coating on a copper component according to Example 1, which shows the microstructuring of the coating from the top view;

2 shows a scanning electron micrograph of the copper trimesate MOF coating on a copper component according to Example 1, which shows the submicrostructuring of the coating from the top view;

FIG. 3 shows an X-ray diffractogram of the copper trimesate MOF coating on a copper component according to exemplary embodiment 1 measured with cobalt K _Q radiation (λ = 1.790307), the 29 value in degrees on the abscissa axis and the signal intensity as Count is plotted linearly on the ordinate axis. Below is a calculated reference diffractogram used for the evaluation;

4 is a scanning electron micrograph of the manganese dihydrogentrimide MOF coating on a stainless steel component according to embodiment 2. The microstructuring of the coating from the top view can be seen;

5 is a scanning electron micrograph of the manganese dihydrogentrimide MOF coating on a stainless steel component according to Example 2. The sub-microstructuring of the coating from the top view is shown;

FIG. 6 shows the X-ray diffractogram of the manganese dihydrogen trime- nate MOF coating measured on cobalt K _Q radiation (λ = 1.790307) on a stainless steel component according to Example 2, the 29 value in degrees on the abscissa axis and the signal intensity as Count is plotted linearly on the ordinate axis. Shown below is a reference powder diffractogram of the MOF compound used for evaluation.

Fig. 7 is a schematic representation of the electrochemical deposition cells according to Examples 1 and 2 with working electrode (AE), counter electrode (GE), reference electrode (RE), salt bridge (SB) and electrolyte (shown hatched).

8 is a schematic representation of wetting states of a water droplet on a) smooth and b), c) on structured, hydrophobic surfaces

Fig. 9 ESEM images a and b show electrochemically deposited Cu-BTC treated with perfluorinated oil. The elevations of the MOF crystals from the liquid film are clearly recognizable. This is shown schematically again in c.

Fig. 10 Impregnated MOF surface in cross-section (sketch) embodiments

Example 1: Impregnated Copper Trimesate MOF Coating on a Copper Member

The surface of the component made of pure copper was first cleaned with a lint-free cellulose cloth soaked in ethanol and then rinsed with deionized water and dried in a stream of air.

In an electrochemical deposition cell (Fig. 7) consisting of a Teflon body in the form of a hollow cylinder open to the upper side and having a circular recess in the bottom, a sealing ring and a Teflon plate screwed on the bottom, the flat component of dimension 1 was obtained , 5 cm x 1, 5 cm of pure copper as a working electrode (anode) connected and coated the introduced into the electrolyte solution surface portion.

In this case, a platinum counter electrode (cathode, area 2 cm x 2 cm) with about 1 cm distance to the working electrode and a mercury / mercury sulfate reference electrode was introduced via a salt bridge in the upper opening of the electrochemical deposition cell.

An area fraction of the working electrode of 0.78 cm ² was added to the electrolytic solution, from 10 ml of a 3: 1 (v / v) mixture of 100% ethanol and deionized water with 0.05 mol / l trimesic acid and 0.06 mol / l tributylmethylammonium methyl sulfate, introduced at a temperature of 50 ° C. A potential of 0.5 V with respect to the mercury / mercury sulfate reference electrode was applied for 10 minutes with a Heka PG310 potentiostat. One minute after completion of the polarization of the electrolyte was removed, the component sample removed and rinsed twice with 15 ml of ethanol and 15 ml of deionized water and dried first in air.

The average layer thickness of the microstructured copper trimsate MOF coating thus produced was determined on the basis of cross-sectional images taken with the Scanning Electron Microscope FEG Gemini Leo 1530 (Zeiss) with an average of 12.5 μm.

The X-ray diffractogram of the copper trimesate MOF coating thus prepared on a flat copper component is shown in Fig. 3 (top) and shows the characteristic signal pattern of a copper trimesate MOF. The reference is a calculated diffractogram of the compound HKUST-1, the structure of which is stored in the Cambrige Structural Database under CCDC number 1 12954 (FIG. 3, bottom). The measurement was carried out in reflection mode with a Philips 1050 diffractometer with a cobalt Ka radiation source (λ = 1.790307 Å).

After drying for three hours, the electrodeposited MOF was impregnated with the Krytox GPL 105 (DuPont) lubricant.

Before impregnation, the surface was first dried for three hours under vacuum conditions at 3 × 10 -3 mbar and room temperature (25 ° C.).

The impregnation was then carried out at ambient pressure under a protective gas atmosphere (argon) in a glove box. The impregnation was carried out by sprinkling the lubricant until the surface was completely covered. In this state, the surface was left for 10 minutes. To remove excess lubricant, the surface was then blown with dry nitrogen for about 20 seconds.

Contact angle measurements according to DIN 55660-2 (coating materials - wettability - Part 2: Determination of the free surface energy of solid surfaces by measuring the contact angle) were carried out on the impregnated surface on the contact angle measuring instrument DSA100 (KRÜSS). The following contact angles were measured:

1 14 ° ± 1 ° for water,

95 ° ± 1 ° for diiodomethane and

61 ° ± 1 ° for acetone. Example 2 Impregnated Manganese Dihydrogen Trimesate MOF Coating on Stainless Steel Member

The surface of the stainless steel component was first cleaned with a lint-free cellulose cloth soaked in ethanol and then rinsed with deionized water and dried in a stream of air.

In an electrochemical deposition cell (Fig. 7) consisting of a Teflon body in the form of a hollow cylinder open to the upper side and having a circular recess in the bottom, a sealing ring and a Teflon plate screwed to the bottom, the flat stainless steel component was made Dimension 1, 5 cm x 1, 5 cm connected as a working electrode (cathode) and coated the introduced into the electrolyte solution area fraction.

In this case, a stainless steel counter electrode (anode, area 1, 6 cm x 3 cm), which was aligned perpendicular to about 0.5 cm from the working electrode, and a mercury / mercury sulfate reference electrode via a salt bridge in the upper opening of the electrodeposition cell introduced.

An area ratio of the working electrode of 0.78 cm 2 was exposed to the aqueous 0.1 mol / l manganese (II) sulfate-containing electrolytic solution at room temperature (23-25 ° C) and a potential of -2.0 V against a mercury / mercury sulfate - Reference electrode applied for a period of 30 minutes with a Methrom Autolab PGSTAT204 potentiostat. Thereafter, the aqueous manganese (II) sulfate electrolytic solution was removed from the electrodeposition cell, and the structure including the manganese plating electrodeposited on the stainless steel member was rinsed three times with 50 ml each of deionized water and once with 50 ml of ethanol, and in air at room temperature for 2 minutes dried.

Rapidly thereafter, to avoid increased oxidation of the manganese coating in air, 10 ml of an electrolyte solution containing 0.05 mol / l trimesic acid and 0.025 mol / l 2-methylimidazole as a structure-directing additive in a 1: 1 (v / v). Mixture of 100% ethanol and deionized water at room temperature into the electrolytic cell.

The device was then switched as a working electrode (anode) to electrochemically control the manganese coating and a platinum counter electrode (cathode, 2 cm ^* 2 cm area) aligned parallel with the working electrode at about 1 cm.

A potential of -1.25 V with respect to the mercury / mercury sulfate reference electrode was observed for 60 min. created. One minute after completion of the polarization of the Electrolyte removed, the component sample removed and rinsed twice with 15 ml of ethanol and 15 ml of deionized water and then dried in air.

The average layer thickness of the microstructured manganese dihydrogen trime- nate MOF coating prepared in this way was determined to be 15.3 μm using cross-sectional images taken with the scanning electron microscope FEG Gemini Leo 1530 (Zeiss).

The X-ray diffraction pattern of the manganese dihydrogen trigentate MOF coating thus prepared on a flat stainless steel component is shown in Fig. 6 (top) and shows the characteristic signal pattern of a manganese dihydrogen trigentate MOF with low intensity, greatly broadened signals based on the nanocrystallinity of the MOF - Crystallite is due. The crystallites additionally form a mesoporous superstructure in the coating composite, which is depicted in FIG. 5.

Due to the small layer thickness, a signal to be assigned to the stainless steel component is also to be observed in the measuring range.

The measurement was carried out in reflection mode with a Philips 1050 diffractometer with a cobalt Ka radiation source (λ = 1.790307 Å).

For the evaluation, a reference sample was prepared which had suitable crystals for an X-ray single crystal structure determination and, after comminution, also X-ray powder diffractometry. The crystals were after seven days from a stored at room temperature 1: 1 mixture of aqueous 0.1 M manganese (II) sulfate solution and a solution analogous to the MOF coating electrolyte (0.05 mol / l trimesic acid and 0.025 mol / l 2-methylimidazole in 1: 1 (v / v) mixture of 100% ethanol and deionized water).

The powder diffraction pattern of this sample, shown as reference in Fig. 6 (bottom), was performed in the transmission mode with a Stoe Stadi P diffractometer with a cobalt Ka1 radiation source (λ = 1.78896 Å). The structure and identity of the compound [Mn (H2BTC) 2 (H20) 4] were determined by X-ray single crystal structure determination. For this purpose, a measurable crystal was selected under the light microscope, glued onto a thin glass thread and measured on an Oxford Diffraction Xcalibur single crystal diffractometer with Sapphire 2 CCD detector at λ = 0.71073 Å. The data reduction was done with Oxford Diffraction's CrysalisRed and the final evaluation steps, structure solution and refinement, with ShelXS and ShelXL implemented in XStep32 by Stoe. After drying for three hours, the electrodeposited MOF was impregnated with the Krytox GPL 105 (DuPont) lubricant.

Contact angle measurements according to DIN 55660-2 were carried out on the impregnated surface on the contact angle measuring device DSA100 (KRÜSS). The following contact angles were measured:

65 ° ± 3 ° for water,

95 ° ± 1 ° for diiodomethane and

65 ° ± 2 ° for acetone.

The reduced water contact angle compared to Example 1 is due to the physicochemical properties of the linker molecule backbone, which has four bonded hydrophilic water molecules per formula unit in the manganese dihydrogentrimide MOF, of which the skeletal structure containing hydrogen bonds in this organometallic compound is dependent. This illustrates the described possibility of influencing the extent of the contact angle increase of the fluids to be condensed by the impregnating agent or by the choice of MOF or linker compounds.

Scanning electron microscopy is a very suitable method (eg in comparison to physisorption measurements) for investigating the MOF coatings produced according to the invention in order to investigate the porosity / structuredness and the shape of the porosity. So it is relevant how the pores are designed on the crystallite surface. The determination of the BET surface area by physisorption measurements, however, is misleading, since a high BET surface area in m2 / g could be due to pores in the "crystallite interior", while the crystallite surface is relatively smooth.

The SEM images show the roughness / structuring in the micrometer scale (FIG. 1 or FIG. 4) as well as in the submicrometer scale or nanoscale (FIG. 2 or FIG. 5) of the superhierarchically structured MOF coating (copper Trimesat MOF coating on a copper component according to Example 1 (see FIG. 1 and FIG. 2) and manganese dihydrogentrimide-MOF coating on a stainless steel member according to Embodiment 2 (see Figs. 4 and 5)).

The "black" areas are the interstices / pores in which the lubricant settles, but without causing a smooth crystallite area.The bright areas are attributable to the crystalline MOF compound, as seen in FIGS. 1, 2, 4, and 5 the morphology / shape of the MOF coatings.

The crystallinity is shown by the reflections in the X-ray diffraction (FIG. 3 or FIG. 6). The pictures are taken before the impregnation.

Claims

claims

1 . Process for coating components with an omniphobic surface coating, comprising at least one organometallic skeleton compound and an impregnating agent, with the steps of

Electrochemical deposition of the organometallic skeleton compound on the component by means of electrolysis, from an electrolyte solution containing at least one metal ion, at least one linker compound and a solvent,

Application of an impregnating agent to the organometallic framework compound,

the metal ion

i) is dissolved as metal ion salt in the electrolyte solution and / or

ii) generated by electrolytic oxidation or reduction of a metal ion precursor contained in the component and / or electrode at the interface between the electrode and the electrolyte solution and / or provided in the electrolyte solution,

and wherein the component

a) is the same electrode

or

b) is introduced into an electric field between at least two electrodes,

wherein the linker compound is an organic, at least monodentate compound, and wherein the impregnating agent has a low surface tension of <30 mN / m.

2. The method according to claim 1, characterized in that the electrochemical deposition takes place potentiostatically, galvanostatically and / or with current and / or voltage pulses.

3. The method according to claim 1, characterized in that the organic, at least monodentate compound contains at least one functional group selected from carboxylate groups, sulfonate groups, phosphonate groups, imidazolate groups, pyridine groups, phenanthroline groups, triazolate groups and / or tetrazolate groups.

4. The method according to any one of claims 1 to 3, characterized in that the linker compound is formed during the electrolysis of at least one linker precursor compound.

5. The method according to claim 4, characterized in that is triggered by the electrochemical reaction of at least one component of the electrolyte solution during the electrolysis, the chemical reaction to form the linker compound from the corresponding linker precursor compound.

6. The method according to claim 4 or 5, characterized in that the linker precursor compound is selected from the free acids or anhydrides of the linker compounds.

7. The method according to any one of claims 1 to 6, characterized in that the electrolyte solution additionally contains a conductive salt and / or structure-directing additive.

8. The method according to any one of claims 1 to 7, characterized in that the at least one metal ion for the synthesis of the organometallic skeleton compound is selected from Cu ⁺ , Cu ²⁺ , Fe ²⁺ , Fe ³⁺ , Co ²⁺ , Co ³⁺ , Al ³⁺ , Mg ²⁺ , Ti ⁴⁺ , Ti ³⁺ , Zr ⁴ *, Mn ³⁺ , Mn ⁴⁺ , Cr ³ ", V ²⁺ , V ³⁺ , V ⁴⁺ , Mo ³⁺ , W ^{3 +} , Ni ²⁺ , ΝΓ, Ag ⁺ , Au ⁺ , Sn ²⁺ , Sn ⁴⁺ , Si ²⁺ , Si ⁴⁺ , Pb ²⁺ , Pb ⁴⁺ and / or Zn ²⁺ .

9. The method according to any one of claims 1 to 8, characterized in that the component is a metal ion precursor containing material.

10. The method according to any one of claims 1 to 9, characterized in that the component comprises an electrically conductive carrier material and a metal ion precursor-containing coating.

1 1. Method according to one of claims 1 to 10, characterized in that the component is connected during the electrochemical deposition as a metal ion generating electrode.

12. The method according to any one of claims 1 to 1 1, characterized in that the component acts as a linker-generating electrode.

13. The method according to any one of claims 1 to 12, characterized in that the impregnating agent is selected from perfluorinated polymers and / or perfluoroalkyl ethers and / or partially fluorinated and / or polyfluorinated polymers or alkyl ethers.

14. Omniphobic surface coating, comprising an organometallic skeleton compound and an impregnating agent, wherein the organometallic skeleton compound micro- and / or meso- and / or macropores, wherein the organometallic skeleton compound has a pore volume of 0.002 cm ³ / g to 3.5 cm ³ / g wherein the organometallic skeleton compound has a specific surface area of 5 m ² / g to 2500 m ² / g, wherein the layer thickness of the surface coating is 100 nm to 1 mm, wherein the impregnating agent has a surface tension of <30 mN / m.

15. Use of an omniphobic surface coating according to claim 14 on components for droplet condensation of fluids having a surface tension of <75 mN / m.

16. Use of an omniphobic surface coating according to claim 14 in heat exchangers.

17. A heat exchanger comprising an omniphobic surface coating according to claim 14 or produced in a method according to one of claims 1 to 13.