WO2017032887A1

WO2017032887A1 - Method for producing siliconized, w/o pickering emulsion-forming particles, and use thereof

Info

Publication number: WO2017032887A1
Application number: PCT/EP2016/070221
Authority: WO
Inventors: Marion Ansorge-Schumacher; Christoph PLIKAT
Original assignee: Technische Universität Dresden
Priority date: 2015-08-27
Filing date: 2016-08-26
Publication date: 2017-03-02
Also published as: DE102015216415A1

Abstract

The invention relates to a method for producing siliconized particles for forming and stabilizing w/o pickering emulsions, to w/o pickering emulsions formed using said particles, and to the use thereof for chemical reactions in multiphase solvent systems. According to the invention, this is achieved by a process using method a), which corresponds to a hydrosilylation, or method b), which corresponds to a vulcanization, in order to produce particles completely or partially coated with silicone.

Description

Process for the preparation of siliconized, w / o Pickering emulsions forming particles and their use

The present invention relates to a process for producing siliconized particles, to the formation and stabilization of w / o Pickering emulsions. Moreover, the invention relates to w / o Pickering emulsions formed with these particles and their use for chemical reactions in multiphase solvent systems.

By emulsion is meant a finely divided mixture of two normally immiscible liquids, e.g. Water (hydrophilic) and oil (hydrophobic). In order to prevent coalescence of the hydrophobic phase droplets finely dispersed in the hydrophilic phase, i. In order to stabilize the emulsion, surfactants such as surfactants or emulsifiers have been used so far mostly. These compounds contain both hydrophobic and hydrophilic functional units and stabilize the dispersed-to-continuous phase interface by lowering the interfacial tension. Surfactants are widely used in the food and cosmetics industry. Decisive disadvantages of these compounds, however, are a high environmental impact, relative toxicity and low biocompatibility. Desorption of the surfactants from the phase boundary can produce undesirable product contaminants. In addition, most stabilized by surfactants emulsions only relatively low storage stability.

Solid-stabilized emulsions have been known for some time. After their discoverer S. U. Pickering these Pickering emulsions are called. Pickering emulsions (PE) are emulsions of two immiscible liquids that are thermodynamically stabilized by nanoparticles or microparticles. These particles are not surface-active, but form a mechanical barrier around the droplets of the inner phase and thus prevent their coalescence. Since a high force has to be used to remove the particles from the phase interface, they are regarded as irreversibly attached. The resulting high storage stability marks a decisive advantage of the Pickering emulsions over conventional, surfactant-stabilized emulsions. In addition, they have a higher resistance to changes in the chemical environment, low toxicity and thus high biocompatibility.

Pickering emulsions are already u.a. used in cosmetic preparations, in the food industry, as pharmaceutical auxiliaries ("drug delivery") and as a template in material synthesis.

So far, however, emulsions of the o / w (oil in water) type have been established industrially, ie the dispersed phase surrounded by particles consists of a hydrophobic liquid, while the continuous phase is formed by a hydrophilic liquid. These o / w PE are stabilized by particles with a hydrophilic surface. These are technically easy to implement and are therefore widely used.

By contrast, PE of type w / o (water in oil) have so far been little described. This is due to the difficult-to-implement, mostly hydrophobic surface properties which the particles must have for the production of these PEs.

So far, this has been achieved by using nanoparticles or microparticles, which inherently have hydrophobic properties or whose surface has been chemically modified in such a way that it is subsequently hydrophobic.

In the literature, Rousseau [1] or Gosh [2] Pickering described emulsions stabilized by nanoparticles consisting of solidified fats. Hikima and Nonomura [3] reported 201 1 the use of keratin particles for the production of w / o PE. Lattuda and Hatton [4] and Xu [5] used Janus particle-like base materials to form w / o PE.

JP 201 1 -178972 A describes the stabilization of w / o / w Pickering emulsions by particles of organic silicone. These contain a spherical cavity and attach themselves to the boundary layer between oil and water phase.

Amphiphilic particles are also used to stabilize w / o Pickering emulsions. No. 6,585,983 B1 describes the coating of metal oxides with oxygen compounds of silicon or aluminum for the preparation of the emulsions and the additional stabilization by electrolytes.

The majority of hydrophobized particles are silanized silicates (see Midmore [6], Arditty et al. [7], Motornov et al. [8], Liu et al. [9], Qi et al. [10], Scott et al.

[1 1], Zhang et al. [12, 13]. Only a few other materials have hitherto been used, such as anhydride-modified starch described by Rayner [14] and Eliasson [15].

A publication by Wu et al. [16] describes the stabilization of w / o Pickering emulsions by hydrophobized silica nanoparticles, obtained by treating the particle surface with trimethoxy (octadecyl) silane. For the first time, the use of Pickering emulsions to perform biocatalyzed reactions in biphasic solvent systems was described. The documents DE 19842732 A1, DE 19842787 A1, DE 19842730 A1 and DE 19842786 A1 describe cosmetic compositions with the main components oil and water, containing w / o or o / w Pickering emulsions, which are stabilized by microfine particles. These particles may include boron nitride particles or color pigments which are coated with dimethylpolysiloxane or polydimethylsiloxane to render the surface amphiphilic. For additional stabilization, emulsifiers and detergents are used.

In DE 19842732 A1, non-amphiphilic metal oxide pigments are additionally added to the composition.

In DE 19842787 A1, the compositions additionally contain an electrolyte.

The compositions according to DE 19842730 A1 additionally contain at least one wax or an oil thickener.

In DE 19842786 A1, the oil phase contains at least one oil component having a viscosity of less than 30 mPa ^* s.

None of the previous approaches provide a general and easy-to-use method for surface modification to make a wide range of nano- or microparticles available for the stabilization of w / o Pickering emulsions, especially without further additives. Only individual, tailored to the particular particle or to the respective compositions modifications are described, which can often be realized only with considerable financial and technical effort.

So far, industrial application of w / o Pickering emulsions has been considerably limited by these difficulties.

EP 201 1865 B1 and EP 2163617 B1 describe novel enzyme preparations which are used in biocatalyzed reaction systems on an industrial scale. In this case, enzymes or enzymes containing microorganisms are immobilized on inert support materials to catalyze chemical reactions, preferably in an aqueous medium. In order to gain a higher stability of the carrier to mechanical forces and to prevent the desorption of the enzymes from the carrier material, they are covered by a silicone layer, which is obtainable by a hydrosilylation reaction. In order to be able to separate the enzyme preparations from the system again after the end of the reaction, carrier sizes on a millimeter scale are necessary. While in EP 201 1865 B1 the silicone material is produced exclusively from siloxanes, it is composed in EP 2163617 B1 of polysiloxanes and polyethers. The object of the present invention is to provide a process for siliconizing particles, both of organic and inorganic origin, that is to say providing them with a silicone coating in order to use them for the formation of Pickering emulsions. This requires an easy-to-use, general method of surface modification of micro- or nanoparticles, which can be used regardless of the nature and structure of the particle surface.

According to the invention the object is achieved by a method for producing siliconized, w / o Pickering emulsions forming particles according to method a) or b).

The inventive method for producing siliconized, w / o Pickering emulsions forming particles according to method a) corresponds to a hydrosilylation comprising the steps: i) wetting of the uncoated particles with an organic solvent or solvent mixture,

ii) preparing a reaction mixture A comprising a solvent or solvent mixture, at least one Si-H-functional polysiloxane of the formula (I) and at least one polyether of the formula (II) carrying at least two terminally unsaturated groups, and a catalyst catalyzing the hydrosilylation,

iii) contacting the wetted particles with the reaction mixture A under hydrosilylation conditions, at temperatures of 0-100 ° C., preferably 0-50 ° C., particularly preferably 0-10 ° C., in particular 4 ° C.,

iv) thorough mixing of the reaction batch at 0-20 ° C., preferably 0-10 ° C., more preferably 0-5 ° C. for 0.5-10 h, preferably 1-7 h, particularly preferably 2-5 h, in particular 4 h .

v) evaporating the solvent or solvent mixture and incubating at 20-200 ° C for 1 to 24 hours.

where (I) = M _a D _b D ' _c T _d corresponds to Qe

With

M = [R ¹ ₂ R ^2a SiO _2/2 ]

D '= [R ¹ R ^2b Si0 _2/2 ]

T = [R ¹ Si0 _3/2 ]

Q = [Si0 _4/2 ]

a = 2 to 10,

b = 1 to 800,

c = 0 to 400, d = 0 to 10,

e = 0 to 10,

where R ^{1 is,} independently of one another or different, selected from the group comprising: saturated or unsaturated, optionally branched alkyl groups having 1 to 30 C atoms, alkaryl radicals having 7 to 30 C atoms, aryl radicals having 6 to 30 C atoms, preferably alkyl groups with 1 to 4 C atoms or phenyl, in particular methyl,

R ^{2a are} independently hydrogen or R ¹ and

R ^{2b is} independently hydrogen or R ¹ and wherein (II) =

(Ii)

corresponds to, with

x ₂ = 0 to 100,

z = 0 to 500,

W = hydrogen or methyl

where R ^{5 is} an optionally branched, optionally substituted, optionally double bond-bearing alkylene radical having 1 to 30 C atoms,

R ^{6 is} independently a radical selected from the group comprising H,

Methyl, ethyl or phenyl,

with the proviso that when z = 0, x ₂ = 0.

It should be clarified at this point that R ^{5 is} a branched or unbranched, substituted or unsubstituted, double bonds or double bonds bearing alkylene radical having 1 to 30 carbon atoms.

The inventive method for producing siliconized, w / o Pickering emulsions forming particles according to method b) corresponds to a vulcanization, comprising the steps: i) wetting the uncoated particles with an organic solvent or solvent mixture,

ii) preparing a reaction mixture B containing a solvent or solvent mixture and 10 to 80% by weight of a vulcanization mixture, based on the total mass of the reaction mixture B, the vulcanization mixture containing 20 to 60% by weight of aliphatic and naphthenic hydrocarbons, 2 to 7% by mole of aminosilane and 0 , 1 to 2 m% N- (3- (trimethoxysilyl) propyl) ethylenediamine, based on the total mass of vulcanization mixture comprises,

iii) contacting the wetted particles with the reaction mixture B, at temperatures of 0-100 ° C,

iv) thorough mixing of the reaction mixture at 0 ° -80 ° C., for 10 minutes-10 hours, v) evaporation of the solvent or solvent mixture and incubation at 0-200 ° C. for 1 to 24 hours.

By definition, m% means% by mass, v% by volume and w% by weight.

The term siliconized particles refers to particles that are completely or partially covered by a silicone layer.

The term solvent, unless otherwise stated, denotes all polar and nonpolar organic solvents.

According to the invention, uncoated particles are used for producing the siliconized, w / o Pickering emulsions stabilizing particles.

In one embodiment of the invention, the uncoated particles consist of organic or inorganic materials or of dried, for example lyophilized microorganisms.

In one embodiment of the invention, the inorganic materials include metals, metal oxides, minerals, inorganic polymers, metal-containing clay materials, zeolites, silicates, hydrogels, ambigels, xerogels, for example silica gel.

In one embodiment, the organic materials comprise synthetic polymers or natural polymers, for example gelatin, as well as hydrogels, ambigels, xerogels, for example of organic polymers.

In one embodiment, the dried microorganisms comprise single cells containing enzymes. In one embodiment, the uncoated particles have a diameter of 1 nm to 10 μm, preferably from 10 nm to 700 nm, particularly preferably from 20 to 250 nm.

According to the invention, the siliconized particles are produced either by method a) which corresponds to a hydrosilylation or by method b) which corresponds to a vulcanization.

The preparation according to method a) is carried out by hydrosilylation of Si-H-functional polysiloxanes in which an at least two terminally unsaturated groups carrying polyether is used as an olefinic building block. The resulting silicone corresponds to a polyether siloxane.

According to the invention, the particles are wetted before the actual reaction with an organic solvent or solvent mixture.

In one embodiment, the organic solvent is selected from polar and / or non-polar solvents, for example cyclohexane or toluene or isopropanol.

In one embodiment, the solvent mixture is a mixture of different nonpolar solvents or it is a mixture of polar and non-polar solvents or it is a mixture of different polar solvents.

In one embodiment, the amount of particles in the solvent during wetting is 20 to 200% (w / v), preferably 40 to 100% (w / v), more preferably 50 to 70% (w / v).

The wetting takes place with stirring of the particles in the solvent or solvent mixture for 10 minutes to 24 hours, preferably 10 minutes to 10 hours, particularly preferably 10 minutes to 1 hour.

In a second reaction vessel is a reaction mixture A, from a solvent or solvent mixture, at least one Si-H-functional polysiloxane of the formula (I) and at least one, at least two terminally unsaturated groups carrying polyether of the formula (II) and a catalyzing the hydrosilylation catalyst produced.

The hydrosilylation may be carried out in the presence or absence of solvent. However, the reaction is preferably in suitable solvents, such as aliphatic or aromatic hydrocarbons, cyclic Oligosiloxanes, alcohols, esters, performed. Suitable solvents are in particular CPME or toluene.

In one embodiment, the concentration of the silylation reagents in the solvent or solvent mixture is 0.1 to 9% (w / v), preferably 0.5 to 5% (w / v), particularly preferably 1 to 3% (w / v).

As Si-H-functional polysiloxanes, preference is given to using Si-H-polysiloxanes of the general formula (I)

M _a D _b D ' _c T _d Q _e (I) where

M = [R ¹ ₂ R ^2a SiO _2/2 ]

D '= [R ¹ R ^2b Si0 _2/2 ] T = [R ¹ Si0 _3/2 ] Q = [Si0 _4/2 ]

N ¹ = a + b + c + d + e = 3 to 850, preferably 6 to 160, a = 2 to 10, preferably 2 to 4, especially 2, b = 1 to 800, preferably 2 to 150, c = 0 up to 400, preferably 2 to 75, d = 0 to 10, preferably 0, e = 0 to 10, preferably 0,

R ¹ independently of one another, identically or differently, selected from the group comprising: saturated or unsaturated, optionally branched alkyl groups having 1 to 30 C atoms, alkaryl radicals having 7 to 30 C atoms, aryl radicals having 6 to 30 C atoms, preferably alkyl groups 1 to 4 C atoms or phenyl, in particular methyl,

R ^{2a are} independently hydrogen or R ¹ and

R ^{2b are} independently hydrogen or R ¹ . It is known to the person skilled in the art that the compounds may be in the form of a mixture with a distribution governed essentially by statistical laws. The values for the indices a, b, c, d and e therefore usually represent mean values.

According to the invention, polyethers carrying at least two terminally unsaturated groups are those of the general formula (II):

(Ii) where

Xi = 0 to 200, preferably 1 to 200, in particular 3 to 100, x ₂ = 0 to 100, preferably 1 to 100, in particular 3 to 100, z = 0 to 500, preferably 0 to 100, W = hydrogen or methyl, preferably hydrogen,

R ^{5 is} an optionally branched, optionally substituted, optionally double bond-bearing alkylene radical having 1 to 30 C atoms,

R ^{6 is} independently a radical selected from the group comprising H, methyl, ethyl or phenyl, with the proviso that when z = 0, x ₂ = 0.

It is known to the person skilled in the art that the compounds may be in the form of a mixture with a distribution governed essentially by statistical laws. The values for the indices Xi and x ₂ therefore usually represent mean values.

In one embodiment, a polyether of general formula (II) is used, wherein Xi + x _{2 is} greater than 1, more preferably greater than 3.

In a further embodiment, a polyether of the general formula (II) is used, where z = 0. In a preferred embodiment of the use of polyethers as the olefinic reaction partner, a polyether of the general formula (II) with z = 0 is used, where

R ^{5 is} an alkylene radical having 1 to 30 C-atoms, preferably having 1 to 9 C-atoms, more preferably having 1 to 4 C-atoms, in particular methylene.

In one embodiment, it is also possible to use mixtures of polyethers which carry at least two terminally unsaturated groups as olefinic reaction partners.

For hydrosilylation, preferably Si-H-functional polysiloxanes are reacted in the presence of catalysts, preferably transition metal catalysts, with polyethers which carry at least two terminally unsaturated hydrocarbon groups.

The hydrosilylation can be carried out according to established methods in the presence of a catalyst.

In this case, for example, catalysts are used which are commonly used for hydrosilylations, such as platinum, rhodium, osmium, ruthenium, palladium, iridium complexes or similar compounds or the corresponding pure elements or their on silica, alumina or activated carbon or similar support materials immobilized derivatives.

In one embodiment, the hydrosilylation is carried out in the presence of Pt catalysts such as cis-platinum or Karstedt catalyst [tris (divinyltetramethyldisiloxane) bis-platinum].

In one embodiment, the amount of catalyst used is 10 ^"7 to 10 ^{" 1} mole per mole of olefin or per mole of terminal carbon-carbon double bond, preferably 1 to 100 ppm.

In one embodiment, 0.5 to 50 m%, preferably 1 to 40 m%, particularly preferably 1 to 25 m%, of siloxane and polyether components are used, based on the mass of the particles used. The siloxane and polyether components are composed in particular of the sum of the compounds of the formula (I) and (II) or of their reaction products.

The hydrosilylation can be carried out using various ratios of the compounds of formula (I) to compounds of formula (II).

In one embodiment, the hydrosilylation is carried out at a molar ratio of the compounds (I) and (II) based on the reactive groups from 1:10 to 10: 1, preferably from 1: 5 to 5: 1, particularly preferably 1: 1, 5 to 1, 5: 1 and most preferably from 1: 1 to 1: 1. The method of the invention according to method a) is also characterized in that the hydrosilylation takes place at particularly low temperatures, so that a more homogeneous structure of the polymer network is formed.

The hydrosilylation is preferably carried out at temperatures of 0 to 100 ° C, preferably 0 to 50 ° C, more preferably 0 - 20 ° C, in particular 4 ° C.

Advantageously, the hydrosilylation is carried out at comparatively low temperatures. The thus slowed reaction rate advantageously allows for greater mixing of the hydrosilylation components, so that hydrophilic and hydrophobic components are distributed more homogeneously within the polymer network than would be the case at high temperatures. Another advantage is the more uniform coating of the particle aggregates within the polymerization reaction. Higher temperatures and resulting higher polymerization rates lead to unfavorable clumping and enlargement of the aggregates.

At the beginning of the hydrosilylation are first the wetted particles with the reaction mixture A, containing a solvent or solvent mixture, Si-H-functional polysiloxane of the formula (I) and at least two terminally unsaturated groups bearing polyether of formula (II) and a hydrosilylation catalyzing catalyst at temperatures of 0 to 100 ° C, preferably 0 to 50 ° C, more preferably 0 - 20 ° C, in particular 4 ° C brought into contact.

During the subsequent thorough mixing of the reaction mixture, the crosslinking of the polymers takes place. The mixing takes place preferably at temperatures of 0-20 ° C., particularly preferably 0-10 ° C., very particularly preferably 0-5 ° C. The mild reaction conditions form a homogeneous polymer network. This ensures that the silicone coating has similar to the same hydrophobicity or hydrophilicity in all areas. The Durchmisschungsprozess is carried out at these temperatures for 0.5 to 10 hours, preferably 1 to 7 hours, more preferably 2 to 5 hours, in particular 4 hours.

A large part of the solvent (mixture) is then removed by at temperatures of 0 to 200 ° C, preferably 20 to 100 ° C, more preferably 50 to 60 ° C over a period of - depending on the solvent - 0.1 to 4h, wherein the Crosslinking of the polymers progresses.

To completely remove the solvent and complete the polymerization, the siliconized particles (aggregates) at 20 to 200 ° C, preferably 30 to 100 ° C, especially preferably incubated at 50 - 60 ° C, wherein the silicone cures and the siliconized particles (- aggregates) provides.

In a preferred embodiment of the process according to method a), the particles are first wetted with a suitable solvent, for example cyclohexane or toluene, or a solvent mixture, for example from isopropanol and hexane with stirring for 12 to 24 hours.

In parallel, at low temperatures of, for example, 4 ° C, the silicone reagents (compounds of formulas (I) and (II) plus catalyst) are dissolved in a suitable solvent, for example cyclohexane, toluene or another organic solvent or solvent mixture, for example from isopropanol and hexane.

In one embodiment, the concentration of the silicone reagents or silylating reagents in the solvent or solvent mixture is 0.1 to 9% (w / v), preferably 0.5 to 5% (w / v), particularly preferably 1 to 3% (w / v) ).

Subsequently, at 4 ° C., for example, the particle suspension is mixed with the reaction mixture of the silicone reagents. So z. B. to 1 g of the respective particles, a mixture of compounds of formula (I) and (II) in a molar mixing ratio of 1: 1 and Karstedt-Kat, eg. 50 ppm based on the amount of silicone components present, and the hydrosilylation at low temperatures of for example 4 ° C instead. It has proved to be advantageous, after addition of the reaction mixture to the particles to stir this mixture for about 4h at for example 4 ° C, z. B. by a magnetic stirrer and the temperature then slowly over at least 30 min to 50 to 60 ° C to increase. Subsequently, the resulting siliconized particle aggregates are dried or hardened in a drying oven at 50 ° C., for example for 12 hours.

The inventive method for producing siliconized, w / o Pickering emulsions forming particles according to method b) corresponds to a vulcanization, comprising the steps: i) wetting of the uncoated particles with an organic solvent or solvent mixture,

ii) preparing a reaction mixture B containing solvent or solvent mixture and 10 to 80 m% of a vulcanization mixture, based on the total mass of the reaction mixture B, wherein the Vulcanization mixture 20 to 60 m% aliphatic and naphthenic hydrocarbons, 2 to 7 m% aminosilane and 0.1 to 2 m% N- (3- (trimethoxysilyl) propyl) ethylenediamine, based on the total mass of vulcanization mixture includes

iv) mixing the reaction mixture at 0 - 80 ° C, for 10 min - 10 h, v) evaporation of the solvent and incubation at 0 - 200 ° C for 1 to 24 h.

According to the invention, the particles are wetted with an organic solvent before the actual reaction.

In one embodiment, the mass ratio of particles to solvent or solvent mixture during wetting is 1: 6 to 1: 1, preferably 1: 4 to 1: 1, more preferably 1: 3 to 1: 1, in particular 1: 2.

In a second reaction vessel, a reaction mixture B containing solvent or solvent mixture and a vulcanization mixture is prepared.

According to the invention, the proportion of vulcanization mixture in the reaction mixture B is from 10 to 80% by mass, based on the total mass of the reaction mixture B.

The proportion of vulcanization mixture in the reaction mixture is preferably from 20 to 70% by mass, more preferably from 30 to 50% by mass, based on the total mass of reaction mixture B. According to the invention, the vulcanization mixture contains from 20 to 60% by weight, preferably from 25 to 55% by weight, particularly preferably from 25 to 50% by weight, of aliphatic and naphthenic hydrocarbons, based on the total mass of the vulcanization mixture.

According to the invention, the vulcanization mixture contains 2 to 7 m%, preferably 2 to 6 m%, particularly preferably 3 to 5 m% aminosilane, based on the total mass of the vulcanization mixture.

In one embodiment, the aminosilane is methyl tris-n-butyl aminosilane.

According to the invention, the vulcanization mixture contains 0.1 to 2 m%, preferably 0.2 to 1, 5 m%, particularly preferably 0.3 to 1 m% N- (3- (trimethoxysilyl) propyl) ethylenediamine, based on the total mass of vulcanization mixture ,

However, other compositions of the vulcanization mixture which serve to produce silicone by vulcanization are also included in the invention.

The vulcanization can be carried out in the presence or absence of solvent. However, the reaction is preferably carried out in organic solvents or solvent mixtures. In one embodiment, the solvents are selected from aliphatic or aromatic hydrocarbons, cyclic oligosiloxanes, alcohols, esters and / or ethers. Suitable solvents are in particular CPME or toluene.

In one embodiment, the mass ratio of the particles used to vulcanization mixture is 6: 1 to 1: 1, preferably 5: 1 to 1: 1.

In the next step, the wetted particles are brought into contact with the reaction mixture and mixed.

According to the invention, this takes place at temperatures of 0-100 ° C., preferably 10-50 ° C., particularly preferably 15-35 ° C., in particular at room temperature.

According to the invention, the mixing of the particles and the reaction mixture takes place at temperatures of 0-80.degree. C., preferably 10-70.degree. C., more preferably 30-70.degree. C. for 0.5-10 h, preferably 1-7 h, particularly preferably 2 5 h, especially 4 h.

In one embodiment, the particles are dried microorganisms, and contacting and mixing of the particles with the reaction mixture are preferably carried out at 35 to 40 ° C. In this case, the crosslinking of the components of the vulcanization mixture takes place and the particles are coated by the silicone formed.

According to the invention after completion of the reaction, the evaporation of the solvent and the incubation of the reaction mixture at 0 to 200 ° C, preferably 20 to 100 ° C, more preferably 30 to 60 ° C instead of for 1 to 24 h.

In one embodiment, the siliconized particles according to the invention have a complete or partial coating of silicone.

In one embodiment, the particles have a partial coating of silicone.

Silicones are known for their excellent biocompatibility and low toxicity. Siloxanes of various functionality are easily and cheaply commercially available. By individually selecting the siloxanes involved in the network formation, one can determine and regulate the physiochemical properties of the silicones, including the hydrophobicity.

Since the coating according to the invention is not a coating bound covalently to the particle, this represents a general method of surface modification of microparticles and nanoparticles, which can be used completely independently of the nature and structure of the particle surface. This makes it accessible to a wide range of micro- and nanoparticles.

In one embodiment, the individual siliconized particles have only a partial coating of silicone. The reason for this is the extremely high specific surface area of the original nanoparticles, which makes them highly prone to agglomeration, that is, the particles are always present as clusters / agglomerates. During the polymerization or vulcanization reaction, these agglomerates are coated with silicone and therefore first siliconized aggregates of the particles are formed.

Only during the dispersion process to produce the w / o Pickering emulsion, these aggregates are mechanically destroyed and decomposed into the individual particles. The silicone layer is thereby torn and on the surface of the individual particles only "islands" of silicone remain behind.The incomplete coating increases the amphiphilia of the particles, that is, the surface has both hydrophobic and hydrophilic areas Particle additionally stabilizing character for the w / o Pickering emulsion.

In one embodiment, the proportion of silicone is 0.5 to 70% of the total mass of the siliconized particles, particularly preferably 1 to 50% of the total mass, very particularly preferably 1 to 30% of the total mass of the siliconized particles. The mass fraction of silicone in the total mass can be adjusted via the amounts of monomers used during the hydrosilylation reaction.

In addition, the particles of the invention have an extremely high biocompatibility and low toxicity, which is a clear advantage over the interface-active substances used hitherto, such as surfactants and emulsifiers.

In addition to the methods a) and b) according to the invention, the silicone coating can also be produced by metal salt-catalyzed condensation of siloxanes and silanols.

The silicone according to the invention has a phase contact angle Θ of 0 ° to 180 °, preferably from 20 ° to 90 °, more preferably from 50 ° to 60 °, most preferably from 55 ° to 59 ° and thus carries rather hydrophilic properties.

The hydrophilicity or hydrophobicity of the surface of the particles plays a crucial role in the stabilization of Pickering emulsions. An orientation of how the surface behaves in this regard is provided by the phase contact angle Θ. The phase contact angle Θ is the angle that forms between continuous (outer) phase and dispersed droplets on the surface of the particles and is verified by goniometric measurements. When θ <90 °, i. In the case of hydrophilic particle surfaces, o / w Pickering emulsions usually form. At phase contact angles of> 90 °, that is, in the case of particularly hydrophobic surfaces of the particles, preference should be given, according to the literature, to w / o Pickering emulsions.

Surprisingly and contrary to the prevailing opinion of experts, stable w / o Pickering emulsions are formed with the siliconized particles according to the invention despite a phase angle of the silicone of Θ <90 °.

The invention thus presents a cost-effective and easy-to-use, general method of surface modification of micro- or nanoparticles, regardless of the nature and structure of the particle surface. In addition, the method w / o pickering provides emulsion particles of low toxicity and high biocompatibility

The invention also siliconized particles prepared by the process according to the invention.

These particles are ideal for stabilizing w / o Pickering emulsions. The invention also encompasses w / o Pickering emulsions containing the siliconized particles prepared according to the invention or the prior art, a continuous phase and a dispersed phase (FIG. 1) vi) wherein the continuous phase of the w / o Pickering emulsion is selected from Solvents having a water solubility of <200g / l H ₂ 0, wherein the dispersed phase of w / o Pickering emulsion is selected from water, aqueous solutions of organic or inorganic salts, hydrogels or highly eutectic solvents wherein the mixing ratio of the dispersed phases to continuous phase in the w / o Pickering emulsion is 1: 1 to 1: 100

wherein siliconized particles of a particulate material or of a mixture of particles of different particulate materials may be used

Pickering emulsions are solid-state emulsions in which particles form a mechanically stable solid film around the dispersed (inner) phase. The particles are considered irreversibly attached, resulting in a high storage stability and high tolerance to changes in the chemical environment.

For the w / o Pickering emulsions according to the invention preferred solvents of the continuous phase are all solvents which have a water solubility of <200 g / l H ₂ 0, preferably <175 g / l H ₂ 0, particularly preferably <150 g / l H ₂ 0 preferably selected from branched, cyclic or aliphatic C5- to C18-hydrocarbons (eg methylcyclohexane, cyclohexane, pentane, hexane, heptane), aromatic hydrocarbons (eg toluene, xylene), aliphatic and branched dialkyl ethers, in particular C4- to C10-dialkyl ethers (eg Methyl tert-butyl ether (MTBTE), diethyl ether, dibutyl ether, diisopropyl ether), aromatic ethers (eg anisole) cyclic ethers (eg cyclopentyl methyl ether (CPME)), alicyclic ethers (eg tetrahydrofuran (THF), 2-methyltetrahydrofuran (MTHF) branched and unbranched alkyl ketones, in particular C 2 - to C 10 -ketones (eg 2-pentanone, 2-hexanone, methyl isobutyl ketone (MIBK)) aliphatic and branched dialkyl esters, in particular C 4 - to C 20 -dialkyl esters, long-chain aliphatic alcohols, preferably C 5 - to C 20 -alcohols and aliphatic ether alcohols such as methoxypropanol, and mixtures thereof.

The dispersed phase solvents used in the w / o Pickering emulsions of the present invention include:

Water and aqueous solutions of organic and inorganic salts, in particular buffer systems (for example potassium phosphate buffer, triethylamine buffer),

Hydrogels e.g. 0.5 to 3% agarose gel, 5 to 30% gelatin,

Strong eutectic solvents (e.g., choline chloride: urea, choline chloride: glycerol).

The mixing ratios of dispersed phase to continuous phase are selected from 1: 1 to 1: 100, preferably from 1: 2 to 1:50, particularly preferably from 1: 5 to 1:20, preferably 1:10.

The siliconized particles used to make the Pickering emulsion according to the invention consist either of a material or a mixture of particles of different materials. For example, the Pickering emulsion according to the invention can be stabilized exclusively by siliconized montmorillonite nanoparticles. However, the stabilization can also be effected, for example, by a mixture of siliconized montmorillonite nanoparticles and siliconized titanium oxide nanoparticles.

In one embodiment, the preparation of the Pickering emulsion according to the invention is carried out with the steps

Wetting of the silicone-coated particles with solvent of the continuous phase, wherein a suspension of continuous phase and particles is formed

- Addition of the phase to be dispersed to the suspension

Homogenization of the mixture of dispersed phase, continuous phase and particles

The wetting of the siliconized particle aggregates according to the invention is preferably involved in the production of the w / o Pickering emulsion of the emulsion formation according to the invention Solvent of the continuous phase ahead. This is done first for 5 to 120 s, preferably 10 to 90 s, particularly preferably 20 s by means of a vortex mixer, on which the suspension is well mixed by vibration and the particle aggregates are already partially broken. It forms a suspension of particles and continuous phase.

In one embodiment, the proportion of particles in the solvent is 0.1 to 10% (w / v), preferably 0.2 to 2% (w / v), particularly preferably 0.5 to 1, 5% (w / v) ,

The incubation of the particles (aggregates) in the continuous phase is then carried out for 5 to 60 minutes, preferably 10 to 40 minutes, more preferably 20 minutes, followed by repeated mixing by means of a vortex mixer for 5 to 120 s, preferably 10 to 90 s preferably 20 s.

This ensures that the particles (aggregates) are sufficiently wetted with a continuous phase in order to then be deposited at the interface to the dispersed phase, without being exposed to excessive wetting.

To form the emulsion, the o.g. Suspension of particles (aggregates) in a continuous phase, the solution of the phase to be dispersed and the mixture by means of homogenizer at speeds of 1 .000 to 40,000 rpm, preferably 5,000 to 30,000 rpm, more preferably 8,000 rpm to 25,000 rpm for 0.5 to Homogenized for 10 minutes, preferably 0.6 to 5 minutes, more preferably 1 to 2 minutes. The resulting mechanical forces ensure that the particle aggregates are completely broken up and that the stabilization of the dispersed phase takes place through the individual, siliconized particles.

In a further embodiment, the wetting of the siliconized particles (aggregates) with solvent of the dispersed phase takes place first. The solvent or solvent mixture of the continuous phase is then added only before homogenization.

In a further embodiment, the solvents of the dispersed phase and of the continuous phase are first mixed by means of vortexers and then the particle aggregates according to the invention are added, which are then broken up by vigorous dispersion into the individual siliconized particles. In turn, the inventive w / o Pickering emulsion forms. The invention likewise relates to the use of the w / o Pickering emulsion according to the invention for chemical reactions in multiphase solvent systems

Chemical reactions often have to be carried out in multiphase solvent systems. This is necessary by the use of reactants of different polarity, which can be solved either only in polar or aqueous solvents or in organic, non-polar solvents. The reaction between the different polar reactants then takes place at the polar-nonpolar solvent interface.

Multiphase solvent systems are understood as meaning a composition of at least two immiscible, for example polar and non-polar solvents. If these are mixed together, for example under mechanical action, dispersions or emulsions are formed. Thus, the interface between the individual phases increases by a multiple and substantially more reactants can react with one another at these interfaces.

However, multiphase solvent systems would immediately separate back into the individual phases without stabilizing agents or particles, which again enormously reduces the interface between the individual phases and severely hampers a complete reaction of all reactants.

Stabilization of multiphase solvent systems for their use in chemical reactions is therefore essential for such reaction systems. Ideally, the stabilizers should behave chemically inert and have no influence on the course of the reaction, unless this is expressly desired.

The invention also provides the use of the w / o Pickering emulsions according to the invention for carrying out chemical reactions in multiphase solvent systems.

In one embodiment, the chemical reactions are biologically or enzymatically catalyzed reactions in multiphase solvent systems.

Enzymatically catalyzed reactions are of great importance, above all, in the preparation of enantiomerically or diastereomerically pure chemical building blocks or active pharmaceutical ingredients. While the reagents for this are mostly soluble only in organic solvents, the enzymes used for catalysis must be submitted predominantly in aqueous solvents, which greatly limits the performance of the reaction. The technical use has hitherto been carried out using emulsions, especially w / o microemulsions, wherein the enzymes are initially introduced in the dispersed, aqueous phase while in the continuous phase reactants and products are dissolved. Disadvantage of these microemulsions, however, is the difficult separation of the enzymes for the economically required multiple or continuous application. In addition, the stabilization of these emulsions has hitherto been carried out using surface-active substances such as surfactants, which, as already described above, considerably limit the possibilities of use, not only by their low biocompatibility and relatively high toxicity, but also by their low stabilization.

W / o Pickering emulsions which are stabilized with siliconized or silicone-coated particles according to the invention or according to the prior art provide a cost-effective and technically easy to implement alternative to the above-mentioned. Surfactant-stabilized microemulsions.

In one embodiment, the starting materials are initially charged in the continuous phase. They diffuse through the particle membrane into the dispersed phase in which the enzyme (s) have been introduced and where the starting materials are catalytically reacted by the respective enzymes. Due to the low water solubility of the reaction products, they are released again into the continuous phase and the enzymes are fed to a renewed catalytic cycle. After completion of the reaction, the enzymes can be easily separated by filtration or sedimentation, purified and reused.

In one embodiment, the enzymatically catalyzed reaction for the stereoselective reduction of acetophenone to enantiomerically pure (S) -I-phenylethanol by means of alcohol dehydrogenase (ADH). The reaction is carried out in a stabilized w / o Pickering emulsion according to the invention with CPME as the continuous phase and aqueous buffer solution as the dispersed phase.

In the continuous, nonpolar phase, the likewise non-polar starting materials, in this case acetophenone, are dissolved. In the aqueous buffer solution, however, the enzyme, here ADH, presented.

The two solutions are homogenized together with the siliconized particles and a stable w / o Pickering emulsion is formed, in which the reaction can take place.

Advantageously, stabilizers of the solvent system do not require any detergents or surfactants which could influence the course of the reaction or have a toxic or inhibiting effect on the catalyzing enzymes.

In one embodiment, the Pickering emulsion according to the invention is used for enzymatically catalyzed reactions in multiphase solvent systems, the Pickering emulsion partially or exclusively by siliconized, dried microorganisms containing catalytically active enzymes is stabilized.

For example, the enzymatically catalyzed reaction takes place in a Pickering emulsion of the invention wherein the particles comprise siliconized lyophilized cells of microorganisms, e.g. E. coli containing catalytically active enzymes.

For this purpose, dried, for example lyophilized cells of the catalytically active enzymes containing microorganisms are siliconized by the novel process and used to stabilize a w / o Pickering emulsion of nonpolar continuous phase and a polar or aqueous solution as a dispersed phase.

In one embodiment, lyophilized E. coli cells are siliconized by the method of the invention and used to stabilize a w / o Pickering emulsion of methyl isobutyl ketone as a continuous phase and an aqueous potassium phosphate buffer solution as a dispersed phase.

In one embodiment, the casein is added to the emulsion as an additional stabilizer, a rather hydrophobic protein which i.a. to stabilize the tertiary structure of the actual enzyme.

In one embodiment, enantiomerically pure R-2,2'-furoin is synthesized from furaldehyde in such a system. Furaldehyde is initially introduced in the continuous phase and passes through diffusion into the only partially siliconized cells. There, it is catalytically reacted by an over-expressed Benzaldehydiyase (BAL) and the product is released back into the continuous phase. A part of the cells is rehydrated by the dispersed phase and is taken up by it. Therefore, a portion of the starting material can diffuse into the dispersed phase to be reacted by the enzymes of the cells dissolved there and to diffuse back into the continuous phase. The product-containing continuous phase can be decanted off after sedimentation of the dispersed phase and the product recovered after removal of the solvent via preparative HPLC or other general isolation methods

For a controlled and slow course of the reaction, the amount of siliconized lyophilized microorganisms needed to form a stable w / o Pickering emulsion is usually too large because too many enzymes are introduced through the cells. Then it is possible to reduce the amount of siliconized cells and to use them together with non-biological, siliconized particles for stabilization.

By contrast, if the Pickering emulsion is stabilized exclusively or almost exclusively by siliconized lyophilized microorganisms, it is possible to react the starting materials complete in minutes or a few hours. This makes it possible to carry out enzyme-catalysed reactions in large-scale processes in the shortest possible time and with the least expenditure of material, which was hitherto unthinkable in the prior art.

With reference to accompanying drawings embodiments of the invention will be explained in more detail. Showing:

Fig. 1: Schematic structure of a w / o Pickering emulsion

FIG. 2a: SEM image of an uncoated montmorillonite nanoparticle. FIG

FIG. 2b: SEM image of a section of the surface of a siliconized montmorillonite nanoparticle. FIG

Fig. 3a: SEM image of uncoated lyophilized cells of E. coli

Fig. 3b: SEM image of the surface of a siliconized lyophilized E. coli cell

Fig. 4: optical micrograph of a w / o Pickering emulsion of water / toluene 1: 5, stabilized by siliconized montmorillonite nanoparticles

Fig. 5: Optical micrograph of a w / o Pickering emulsion of water / ethyl acetate 1: 5, stabilized by silicone-coated lyophilized E. coli cells

Fig. 6: Reaction course of the stereoselective reduction of acetophenone to enantiomerically pure (S) -1-phenylethanol

Figure 7: Reaction course of the stereoselective reaction of furaldehyde to R-2,2'-furoin in a w / o Pickering emulsion stabilized by siliconized lyophilized £. coli cells. (· = Concentration curve of furaldehyde as a function of time, ▲ = concentration curve of (R) -furoin as a function of time)

Embodiment 1 a

Preparation of siliconized montmorillonite nanoparticles by method a)

0.5 g of the montmorillonite nanoparticles (d <100 nm, BET> 14.0 m ² / g from Sigma-Aldrich) are vortexed at 4 ° C. with 5 mL of a solvent mixture of isopropanol: hexane (10: 1) in an Erlenmeyer flask first mixed well at 1000 rpm and then allowed to stand at 4 ° C for 12 h for sufficient wetting. In parallel, 91 mg of C3-PEG400 (polyether component (II)) and 20 mg of D-siloxane (polysiloxane component (I)) are mixed in a separate flask. For this purpose, 10 ml_ of a temperature-controlled to 4 ° C solvent of isopropanol: hexane (10: 1) and mixed thoroughly by means of vortexer. The above-mentioned wetted particles are added to this mixture and thoroughly mixed again by means of vortexing. After adding 5 μί Karstedt catalyst mix thoroughly again.

The reaction mixture is then stirred on a magnetic stirrer at 4 ° C first with a stirring speed of 1000 rpm for 30 min and then with a stirring speed of 500 rpm for 3.5 h. After the reaction time, the solvent mixture is removed at 50-60 ° C within 0.5 to 1 h by evaporation.

For the final cross-linking, the reaction mixture is incubated for 12 h at 50-60 ° C. Gum-like powdery particles or particle aggregates are obtained which have full or at least partial coverage with silicone.

FIG. 2a shows an SEM image of uncoated montmorillonite nanoparticles. FIG. After the silicone coating according to the invention, the surface of the particles acquires a raspberry-like structure. (Fig. 2b)

Embodiment 1 b

Preparation of siliconized lyophilized cells of E. coli according to method a)

91 mg C3-PEG400 (polyether component (II)) and 20 mg D-siloxane (polysiloxane component (I)) are mixed with 3 mL CPME and cooled to 4 ° C. 5 μί Karstadt catalyst are added to this mixture. In parallel, 0.5 g of powder are placed in a separate flask, followed by the addition of the cooled monomer / catalyst mixture and mixing. The mixture is slowly heated to 40 ° C with vigorous stirring, the solvent evaporating and the mixture appears dry again. This gives siliconized, Aggreagaten combined E. coli cells that can be stored at -20 ° C.

In Fig. 3a, an SEM image of the uncoated, lyophilized cells of £. coli. FIG. 3b shows one of these cells after the coating according to the invention. One can clearly see the rough and irregular structure of the surface, which indicates incomplete coverage. Embodiment 2 a

Preparation of a Pickering emulsion with silicone-coated montmorillonite nanoparticles

15 mg of the according to Example 1 a siliconized montmorillonite nanoparticles aggregates are suspended in a 50 ml falcon tube in 16 ml of cyclopentyl methyl ether (CPME). The suspension is thoroughly mixed by vortexing for 20 s, then allowed to incubate for 20 min and mixed again by means of vortexing for 20 s. Subsequently, 3 ml of the aqueous phase are added and the mixture is homogenized by means of a homogenizer (for example IKA Ultraturrax T25) for 1 min at 8000 rpm.

4 shows photomicrographs of the w / o Pickering emulsion of CPME / water 5: 1, stabilized by montmorillonite nanoparticles siliconized according to the invention. The regular distribution of the dispersed droplets proves the stability of the emulsion and the prevented coalescence of the dispersed phase.

Embodiment 2 b

Preparation of a Pickering emulsion with siliconized lyophilized cells of E. coli

15 mg of the according to Example 1 b coated lyophilized cells of E. coli are suspended in a 50mL Falcon tube in 16 mL of methyl isobutyl ketone. The suspension is thoroughly mixed by vortexing for 20 s, then allowed to incubate for 20 min and mixed again by means of vortexing for 20 s. Subsequently, 4 mL of the aqueous phase are added and the mixture is homogenized by homogenizer (e.g., IKA Ultraturrax T25) for 1 min at 8000 rpm.

5 shows a light micrograph of the w / o Pickering emulsion with methyl isobutyl ketone / water 5: 1, stabilized by silicone-coated lyophilized cells of E. coli. The regularly distributed dispersed droplets show that the coalescence of the dispersed phase is greatly restricted or completely prevented.

Embodiment 3

Use of a prepared according to embodiment 2a w / o Pickering emulsion as

Reaction system for the stereoselective reduction of acetophenone to enantiomerically pure (S) -1-phenylethanol 0.540 g (250 mmol) of acetophenone are dissolved in a mixture of 0.9 ml of isopropanol and 14.8 ml of cyclopentyl methyl ether (CPME): heptane (1: 2) and thoroughly mixed using a vortexer.

At the same time, 240 mg of the montmorillonite nanoparticles coated according to Example 1 a are weighed into a falcon and cooled to 0 ° C. First add the above mentioned acetophenone solution and then add 4 ml of a solution of purified alcohol dehydrogenase (ADH - protein content: 15 mg / ml) in KPi buffer solution (50 mM, pH 7.55 in H ₂ O) with NADH- Cofactor (1mM) added. The mixture is homogenized by homogenizer at 0 ° C for 1 min at 8000 rpm. Subsequently, the reaction mixture is incubated in a thermo cabinet for 48 h at 40 ° C and 30 rpm. The course of the reaction is monitored by determining the concentration of starting material and product by means of HPLC. Figure 6 shows the increase in the concentration of (S) -I-phenylethanol over time and, correspondingly, the decrease in the concentration of acetophenone until the balance is established.

Embodiment 4

Use of a prepared according to embodiment 2b w / o Pickering emulsion as a reaction system for the stereospecific carboligation of furaldehyde to (R) -2,2'-Furoin

To prepare the dispersed phase, 120 mg of the according to Example 1 b siliconized, lyophilized cells of E. coli are suspended in 4 mL KPi buffer. For this purpose, 16 mL of a 312 mM solution of furaldehyde in methyl isobutyl ketone (MIBK) are added, the mixture is cooled to 0 ° C and thoroughly mixed by vortexing at 8000 rpm for 1 min. Subsequently, the reaction mixture is incubated for 24 h at 37 ° C in a thermobox. The reaction is monitored by determining the concentrations of substrate and product. After completion of the reaction, the dispersed phase is separated from the continuous phase by centrifugation. The product is recovered from the continuous phase by known purification processes.

Fig. 7 shows the course of the concentration of substrate (furaldehyde ·) and product (R-2.2 ¹ - Furoin ▲) as a function of time. Embodiment 5a

Production of siliconized iron (II, IIQ oxide nanoparticles according to method b)

A 15 ml Falcon tube is treated with 900 mg vulcanization mixture containing> 25 to <50 m% aliphatic and naphthenic hydrocarbons,> 3 to <5 m% methyltris-n-butylaminosilane,> 0.3 to <1 m% N- (3- (trimethoxysilyl) propyl) ethylenediamine and> 0.1 to <0.3 m% toluene, for example Elastosil A316 (Wacker Chemie AG) filled to 4.0 ml volume with a mixture of hexane: isopropanol (9: 1) filled and mixed thoroughly using a vortexer.

1 g of iron (II, III) oxide nanoparticles are placed in a second 15 ml Falcon tube and pre-wetted with 2 ml of a solvent mixture of hexane: isopropanol (9: 1) by mixing for 20 min.

Subsequently, 4 ml of the dissolved vulcanization mixture (reaction mixture B) are added to the particle suspension and thoroughly mixed for 30 seconds by means of a vortexer. The particle reaction mixture batch is placed in a dish and mixed by means of magnetic stirrer or manual mixing with spatula at 50 to 60 ° C.

When the solvent mixture has evaporated and the particles are flocked and gummed siliconized, place the mixture in a small beaker and allow to polymerize overnight at 50 ° C.

Gum-like powdery particles or particle aggregates are obtained which have full or at least partial coverage with silicone.

Embodiment 5 b

Production of siliconized, lyophilized E. coli cells according to method b)

A 15 ml Falcon tube is at room temperature with 225 mg vulcanization mixture containing> 25 to <50 m% aliphatic and naphthenic hydrocarbons,> 3 to <5 m% methyl tris-n-butylaminosilane,> 0.3 to <1 m% N- (3- (trimethoxysilyl) propyl) ethylenediamine and> 0.1 to <0.3 m% toluene, for example Elastosil A316 (Wacker Chemie AG), filled, made up to 4.0 ml volume with cyclopentyl methyl ether (CPME) and strong by vortexer mixed.

0.5 g of lyophilized E. coli cells are placed in a second 15 ml Falcon tube and pre-wetted with 2 ml of CPME by mixing for 20 min.

Subsequently, 4 ml of the dissolved vulcanization mixture (reaction mixture B) are added to the cell suspension at room temperature and thoroughly mixed for 30 seconds by means of a vortexer. The cell reaction mixture batch is placed in a dish and mixed by means of a magnetic stirrer or manual mixing with a spatula at 40 ° C. When the solvent mixture has evaporated and the particles are flocked and gummed siliconized, place the mixture in a small beaker and allow to polymerize overnight at 40 ° C.

literature

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[2] S. Gosh and D. Rousseau, Currrent Opinion in Colloid & Interface Science, 201 1, 16, 421-431

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Claims

claims

1 . Process for the preparation of siliconized, w / o Pickering emulsions forming particles from uncoated particles according to method a) or b) wherein method a) corresponds to a hydrosilylation, comprising the steps: i) wetting the uncoated particles with an organic solvent or solvent mixture,

iii) contacting the wetted particles with the reaction mixture A under hydrosilylation conditions, at temperatures of 0-100 ° C,

iv) mixing the reaction mixture at 0 - 20 ° C for 0.5 - 10 h

v) Evaporate the solvent and incubate at 20-200 ° C for 1 to 24 hours. where (I) = M _a D _b D ' _c T _d corresponds to Qe

With

M = [R ¹ ₂ R ^2a SiO _2/2 ]

D '= [R ¹ R ^2b Si0 _2/2 ]

T = [R ¹ Si0 _3/2 ]

Q = [Si0 _4/2 ]

a = 2 to 10,

b = 1 to 800,

c = 0 to 400,

d = 0 to 10,

e = 0 to 10,

wherein R ^{1 are} independently the same or different, selected from the

Group comprising: saturated or unsaturated, optionally branched

Alkyl groups having 1 to 30 carbon atoms, alkaryl groups having 7 to 30 carbon atoms, aryl groups having 6 to 30 carbon atoms, preferably alkyl groups having 1 to 4 carbon atoms or

Phenyl, especially methyl,

R ^{2a are} independently hydrogen or R ¹ and

R ^{2b is} independently hydrogen or R ¹ and where (II) =

(Ii)

corresponds to, with

x ₂ = 0 to 100,

z = 0 to 500,

W = hydrogen or methyl

where R ^{5 is} a branched or unbranched, substituted or unsubstituted, double bond or no double bond-bearing alkylene radical having 1 to 30 carbon atoms,

R ^{6 is} independently a radical selected from the group comprising H,

Methyl, ethyl or phenyl,

with the proviso that when z = 0, x ₂ = 0, and wherein method b) corresponds to vulcanization, comprising the steps of:

i) wetting the uncoated particles with an organic solvent or solvent mixture,

iv) thorough mixing of the reaction mixture at 0 ° -80 ° C., for 10 minutes-10 hours, v) evaporation of the solvent or solvent mixture and incubation at 20-200 ° C. for 1 to 24 hours.

2. The method according to claim 1, characterized in that the uncoated particles consist of organic or inorganic materials or of lyophilized microorganisms.

3. The method according to claim 1 or 2, characterized in that the organic materials comprise synthetic or natural polymers, Ambigele, xerogels or hydrogels and that the inorganic materials include metals, metal oxides, minerals, inorganic polymers, metal-containing clay materials, zeolites, silicates, hydrogels, Ambigels, xerogels include and that the lyophilized microorganisms comprise enzymes containing unicellulars.

4. The method according to any one of claims 1 to 3, characterized in that the uncoated particles have a diameter of 1 nm to 10 μηη.

5. The method according to any one of claims 1 to 4, characterized in that the siliconized particles have a complete or partial coating of silicone.

6. The method according to any one of claims 1 to 5, wherein the proportion of silicone is 0.5 to 50% of the total mass of the siliconized particles.

7. A siliconized particle prepared by a process according to any one of claims 1 to 6.

8. w / o Pickering emulsion containing siliconized particles, produced according to one of claims 1 to 6 or according to a method of the prior art, with a continuous and a dispersed phase,

wherein the continuous phase of the w / o Pickering emulsion is selected from solvents which have a water solubility of <200 g / l H ₂ 0,

wherein the dispersed phase of the w / o Pickering emulsion is selected from water, aqueous solutions of organic or inorganic salts, hydrogels or strongly eutectic solvents,

wherein the mixing ratio of the dispersed phases to the continuous phase in the w / o Pickering emulsion is 1: 1 to 1: 100 wherein siliconized particles of a particulate material or a mixture of siliconized particles of different particulate materials may be used

9. Use of a w / o Pickering emulsion according to claim 7 for chemical reactions in multi-phase solvent systems.

10. Use according to claim 8, characterized in that the chemical reactions are biologically or enzymatically catalyzed reactions in multi-phase solvent systems.

1 1. Use according to claim 9, characterized in that the Pickering emulsion is partially or exclusively stabilized by siliconized, dried microorganisms containing catalytically active enzymes.