HYBRID POLYMER AND ITS USES

Abstract

The invention relates to a hybrid polymer obtained by a radical polymerization process involving the precipitation of at least one monomer comprising at least one unsaturated ethylenic group, in the presence of at least one protein. The invention also relates to the use of said hybrid polymer as a viscosifying agent in various formulations or compositions.

Description

Description Title of the invention: HYBRID POLYMER AND ITS USES READINGS Technical field

[0001] = The invention belongs to the technical field of hybrid polymers. More pre- Specifically, the invention relates to a hybrid polymer obtained by a poly- radical merization by precipitation of at least one monomer comprising at least an unsaturated ethylenic function, in the presence of at least one protein. The invention also aims at the use of said hybrid polymer as a viscosifying agent in various formulations or compositions. Prior art

[0002] — Synthetic polymers have been used for many years as agents viscosifiers in several application areas to increase the viscosity of various aqueous preparations.

[0003] — These polymers have unmatched application performance, however they are 100% from fossil resources. A recent shortage of monomers to produce these synthetic polymers has been observed due to the increasing demand and insufficient crude oil reserves. It is therefore necessary to replace these synthetic polymers by hybrid polymers which are at least partially derived from renewable natural sources. These hybrid polymers retain optimal application characteristics.

[0004] — Grafting of natural materials such as sugars and starches with monomers is already described in the literature. For example, US Pat. 5,854,191, 5,223,171, 5,227,446 and 5,296,470 disclose the use of graft copolymers in cleaning applications. Patents WO / 18108663-65-67 describe the use of such hybrids for cosmetic compositions.

[0005] — These hybrid thickening polymers are a good alternative, however their use- lization remains very specific to a given application domain. They do not adapt to applications with more difficult experimental conditions, such as petroleum applications, for example, which require the polymer to withstand high temperatures. temperatures.

[0006] Thus it is more than necessary to develop a universal viscosifying agent, meeting the application characteristics expected in various fields of application.

[0007] — Unexpectedly, the Applicant has developed a hybrid polymer obtained by radical precipitation polymerization remedying the pre- disadvantages previously cited. Summary The present application relates to a hybrid polymer obtained by radical precipitation polymerization between at least one monomer comprising at least one unsaturated ethylenic function, and in the presence of at least one protein. More specifically, the invention relates to a hybrid polymer (PH) in particulate form. This hybrid polymer (PH) is obtained by a radical precipitation polymerization process according to the following successive steps: (A) Prepare a solution (S1) comprising: - 50 to 95% by weight of at least one polar solvent, - 4 to 40% by weight of at least one monomer comprising at least one unsaturated ethylenic function, and - 0.1 to 40% by weight of at least one protein; the percentages being given relative to the total weight of (SI), and making a total of 100%; (B) Initiating the polymerization in the solution (S1) to obtain a dispersion (D1) comprising at least one hybrid polymer (PH); (C) Isolate the hybrid polymer (PH), in particulate form, from the dispersion (D1). The invention also relates to the use of said hybrid polymer (PH) as a viscosifying agent. The invention also relates to a viscosity modifying agent comprising at least one hybrid polymer (PH) according to the invention. Brief description of the drawings Fig. 1 [Fig.1] illustrates the NMR / DOSY spectrum of serum protein alone. Fig.2 [Fig.2] illustrates the NMR / DOSY spectrum of the hybrid polymer (PH). Description of the embodiments Definitions and generalities Throughout this application, the following definitions apply unless specifically indicated otherwise. All intervals are inclusive and combinable. Ranges of values ​​include the lower and upper bounds. Thus, the ranges of values ​​"between 0.1 and 1.0" and "from 0.1 to 1" include the values ​​0.1 and 1.0. The number of significant figures does not constitute a limitation on the quantities shown, nor does it limit the accuracy of the data. As used herein, the term "hydrophilic monomer" means a monomer whose octanol / water partition coefficient, Kow, is less than 1, determined at a temperature of 25°C and with a pH between 6 and 8, As used herein, the term "hydrophobic monomer" means a monomer whose octanol / water partition coefficient, Kow, is greater than 1, as determined at a temperature of 25°C and a pH between 6 and 8. The partition coefficient Kow is defined as follows: [Math.1] menomer]octanol Kow= Lmonomer Joctemol [monomer game With | monomer |octanol = equilibrium solubility concentration of the monomer in g / L in n-octanol [monomer] water = equilibrium concentration of the monomer in g / L in water. According to the present invention, the weight average molecular weight of the synthetic polymers according to the invention is determined by measuring the intrinsic viscosity. The intrinsic viscosity can be measured by methods known to those skilled in the art and can in particular be calculated from the reduced viscosity values ​​for different concentrations by a graphical method consisting of plotting the reduced viscosity values ​​(on the y-axis) as a function of the concentrations (on the x-axis) and extrapolating the curve to a zero concentration. The intrinsic viscosity value is read on the y-axis or using the least squares method. Then, the weight average molecular weight can be determined by the well-known Mark-Houwink equation: [mn] = K.Ms [mn] represents the intrinsic viscosity of the polymer determined by the solution viscosity measurement method, K represents an empirical constant, M represents the molecular weight of the polymer, a represents the Mark-Houwink coefficient, a and K depend on the particular polymer-solvent system. Tables known to those skilled in the art give the values ​​of œ ct K sclon lc polymer-solvent system. According to the present invention, the monomers comprising at least one unsaturated ethylenic function mentioned above can polymerize with each other to form polymers. The term "polymer" designates a product formed by the polymerization of two or more monomers. Polymers made from a single type of monomer are called homopolymers. Polymers made from two or more different types of monomers are called copolymers. As used herein, the term "water-soluble polymer" means a polymer that gives an aqueous solution without insoluble particles when dissolved with stirring for 4 hours at 25°C at a concentration of 2 gL"! in deionized water. An "anionic polymer" means a polymer containing monomers anionic and optionally non-ionic monomers. A “non-ionic polymer” means a polymer containing only non-ionic monomers. An amphoteric polymer is a polymer comprising cationic charges and anionic charges, preferably as many anionic charges as cationic charges, it can also contain a non-ionic monomer. The term "particle size" refers to the average size, in number, of the water-soluble polymer particles. It corresponds to the largest dimension, for example the diameter for spherical particles, preferably measured with a laser measuring device using conventional techniques that are part of the knowledge of a person skilled in the art. A Mastersizer type device from Malvern, for example the MS2000, may be used for this purpose. This type of device makes it possible to measure, by laser diffraction, the particle size distribution of particles in a liquid medium or in solid form. By "monomer unit" is meant the chemical unit relative to the corresponding monomer when it is found polymerized in the polymer chain of the polymer. By "protein unit" we mean the chemical unit relative to a corresponding protein, when it is grafted into the polymer chain of the polymer. The invention therefore relates to a hybrid polymer (PH) in particulate form obtained by a radical precipitation polymerization process according to the following successive steps: (A) Prepare a solution (S1) comprising: - 50 to 95% by weight of at least one polar solvent, - 4 to 40% by weight of at least one monomer comprising at least one unsaturated ethylenic function, and - 0.1 to 40% by weight of at least one protein; the percentages being given relative to the total weight of (SI), and making a total of 100%; (B) Initiating the polymerization in the solution (S1) to obtain a dispersion (D1) comprising at least one hybrid polymer (PH); (C) Isolate the hybrid polymer (PH), in particulate form, from the dispersion (D1). The solution (S1) is preferably produced by first mixing the monomer(s) having at least one unsaturated ethylenic function and at least one polar solvent, then the protein(s) is added to this mixture. The monomer(s) comprising at least one unsaturated ethylenic function of step (A) are preferably hydrophilic monomers. The hydrophilic monomer(s) are preferably non-ionic and / or anionic, such that when they are non-ionic they are chosen from acrylamide, methacrylamide, N,N-dimethylacrylamide, N-vinylformamide, N-vinyl acetamide, N-vinylpyridine, N-vinylpyrrolidone, acryloyl morpholine (ACMO), diacetone acrylamide, or a mixture of these monomers, and when they are anionic they are chosen from the group comprising monomers having a carboxylic acid function and their salts, monomers having a sulfonic acid function and their salts or monomers having a phosphonic function and their salts, or a mixture of these monomers. The solution (S1) preferably comprises from 10 to 30% by weight of at least one hydrophilic monomer; the percentage being given relative to the total weight of the solution (S1), In step (A), the solution (S1) is preferably prepared from a mixture of polar solvents, and at least one monomer comprising at least one unsaturated ethylenic function, said mixture of polar solvents comprising 0.5% to 10% by weight of water, and at least 90% by weight of an alcohol comprising 1 to 4 carbons. The alcohol comprising 1 to 4 carbons is preferably tert-butanol. The mixture of polar solvents preferably comprises from 1 to 5% by weight of water and from 95 to 99% by weight of tert-butanol. The protein is preferably chosen from proteins of animal or plant origin and / or their mixtures. The protein is preferably a casein, a whey protein, a wheat protein or their mixtures. The hybrid polymer (HP) preferably comprises monomeric units of at least one monomer comprising at least one unsaturated ethylenic function, and protein units, said monomeric units and said protein units being partially or totally linked by at least one covalent bond. The hybrid polymer (HP) preferably has a weight average molecular weight between 200,000 and 2,000,000 daltons. The invention also relates to the use of the hybrid polymer (HP) according to the invention as a viscosifying agent in the recovery of hydrocarbons; in the drilling and cementing of wells; in the stimulation of hydrocarbon wells; in the manufacture of paper; in construction; in the mining industry; in the formulation of cosmetic products; in the formulation of detergents; or in the manufacture of textiles. The invention also relates to a viscosifying agent comprising at least one hybrid polymer (HP) according to the invention in the recovery of hydrocarbons; in the drilling and cementing of wells; in the stimulation of hydrocarbon wells; in paper manufacturing; in construction; in the mining industry; in the formulation of cosmetic products; in the formulation of detergents; or in textile manufacturing. The invention also relates to an aqueous composition thickened with a hybrid polymer (PH) according to the invention. Monomers comprising at least one unsaturated ethylenic function The hybrid polymer (PH) according to the invention is obtained by precipitation polymerization of monomers comprising at least one unsaturated ethylenic function and in the presence of at least one protein. Preferably, the solution (S1) comprises between 4% and 40% by weight of monomers comprising at least one unsaturated ethylenic function, even more preferably from 10 to 30%, the percentages by weight being given relative to the total weight % of the solution (S1). Said monomers may be of a synthetic and / or bio-sourced nature. Advantageously, these monomers are preferably hydrophilic monomers. The hydrophilic monomers are non-ionic, anionic, cationic or zwitterionic. Preferably, these monomers have a single ethylenic unsaturation (double bond between two carbon atoms). Advantageously, the non-ionic monomer(s) that can be used in the context of the invention are chosen, in particular, from the group comprising water-soluble vinyl monomers, such as acrylamide, methacrylamide, N-alkylacrylamides, N-alkylmethacrylamides, N,N-dialky]acrylamides (for example N,N-dimethylacrylamide or N,N-diethylacrylamide), N,N-dialkylmethacrylamides, alkoxylated esters of acrylic acid, alkoxylated esters of methacrylic acid, N-vinylpyrrolidone, N-methylolacrylamide, N-vinylformamide (NVF), N-vinyl acetamide, N-vinyl imidazole, N-vinyl succinimide, acryloyl morpholine. (ACMO), acryloyl chloride, glycidyl methacrylate, glyceryl methacrylate, diacetone acrylamide, hydroxyalkyl (meth)acrylate, aminoalkyl (meth)acrylate, thioalkyl (meth)acrylate, hydroxyalkylacrylates, hydroxyalkyl methacrylates, and mixtures thereof.Among these non-ionic monomers, the alkyl groups are advantageously C1-C5, more advantageously C1-C3. These are preferably linear alkyls. Preferably, the non-ionic monomer is acrylamide. The solution (S1) advantageously comprises between 1 and 99 mol% of non-ionic monomer(s), preferably between 2 and 70 mol%, the molar percentage being expressed relative to the total number of moles of monomers in the solution (S1). Advantageously, the anionic monomer(s) may be selected from a broad group. These monomers may have vinyl, acrylic, maleic, fumaric, malonic, itaconic, or allylic functions, and contain a carboxylate, phosphonate, phosphate, sulfate, sulfonate, or other anionically charged group. Examples of suitable monomers include acrylic acid; methacrylic acid; dimethylacrylic acid; itaconic acid; crotonic acid; maleic acid; fumaric acid; acrylamido undecanoic acid; 3-acrylamido 3-methylbutanoic acid; maleic anhydride; strong acid monomers having for example a sulfonic acid or phosphonic acid function such as vinylsulfonic acid, vinylphosphonic acid, alkylsulfonic acid, methallylsulfonic acid, acid 2-methylidenepropane-1,3-disulfonic acid, 2-sulfoethylmethacrylate, sulfopropylmethacrylate, sulfopropylacrylate, allylphosphonic acid, styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid (ATBS), 2-acrylamido-2-methylpropane disulfonic acid; water-soluble salts of these monomers such as their alkali metal salts (as distinct from the crystalline form of the sodium salt of 2-acrylamido-2-methylpropane sulfonic acid), alkaline earth metal salts, or ammonium salts; and mixtures thereof. Preferably, the anionic monomer(s) is acrylic acid and / or its salts. The solution (S1) advantageously comprises between 1 and 99 mol% of anionic monomer(s), preferably between 2 and 70 mol%, more preferably between 3 and 50 mol%, the molar percentage being expressed relative to the total number of moles of monomers in the solution (S1). According to one aspect of the invention, the carboxylic acid functions of the anionic monomer are salified by a salifying agent, also called a neutralizing agent. By salified, it is meant that at least one acid function of the anionic monomer is replaced by a salt neutralizing the negative charge of the acid function. In other words, the non-salified form corresponds to the acid form of the monomer, for example R- C(=O)-OH in the case of the carboxylic acid function, while the neutralized form of the monomer corresponds to the form RC(=O)O- X+, X+ corresponding to a positively charged ion. The neutralization of the acid functions may be partial or total. Generally, salification is done before polymerization. In a particular embodiment of the invention, between 30 and 100 mol% of the acid functions are salified, more advantageously between 60 and 100 mol%. The salifying agent is advantageously a Brgnsted base. It is preferably chosen from ammonia, sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, and mixtures thereof. Ammonia is particularly preferred. Advantageously, the cationic monomer(s) which may be used in the context of the invention are chosen from monomers derived from vinyl-type units, in particular acrylamide, acrylic, allyl or maleic, these monomers having a phosphonium or quaternary ammonium function. Mention may be made, in particular and in a non-limiting manner, of quaternized dimethylaminoethyl acrylate (ADAME), quaternized dimethylaminoethyl methacrylate (MADAME), dimethyldiallylammonium chloride (DADMAC), acrylamido propyltrimethyl ammonium chloride (APTAC), and methacrylamido propyltrimethyl ammonium chloride (MAPTAC). The quaternizing agent may be chosen from alkyl chlorides, dialkyl sulfates or alkyl halides. Preferably, the quaternizing agent is chosen from methyl chloride and diethyl sulfate. The solution (S1) advantageously comprises between 5 and 35 mol% of cationic monomer(s), the molar percentage being expressed relative to the total number of moles of monomers in the solution (S1). A person skilled in the art will know how to prepare the quaternized monomers, for example using alkyl halide of the R*-X type, R* being an alkyl group and X being a halogen (in particular methyl chloride). In addition, the present invention also covers monomers of the DADMAC, APTAC, and MAPTAC type whose halide counterion is fluoride, bromide or iodide instead of chloride. Advantageously, the zwitterionic monomer(s) may be a derivative of a vinyl-type unit, in particular acrylamide, acrylic, allylic or maleic, this monomer having an amine or quaternary ammonium function and an acid function of carboxylic (or carboxylate), sulfonic (or sulfonate) or phosphoric (or phosphate) type. Mention may be made, in particular and without limitation, of derivatives of dimethylaminoethyl acrylate, such as 2-((2-(acryloyloxy)ethyl) dimethylammonio) ethane-1-sulfonate, 3-({2-(acryloyloxy)ethyl) dimethylammonio) propane-1-sulfonate, 4-((2-(acryloyloxy)ethyl) dimethylammonio) butane-1-sulfonate, [2-(acryloyloxy)ethyl] (dimethylammonio) acetate, derivatives of dimethylaminoethyl methacrylate such as 2-((2-(methacryloyloxy)ethyl) dimethylammonio) ethane-1-sulfonate, 3-((2-(methacryloyloxy)ethyl) dimethylammonio) propane-1-sulfonate, 4-((2-(methacryloyloxy) ethyl) dimethylammonio) butane- 1-sulfonate,[2-(methacryloyloxy)ethyl](dimethylammonio)acetate, dimethylaminopropylacrylamide derivatives such as 2-((3-acrylamidopropyl)dimethylammonio)ethane-1-sulfonate, 3-((3-acrylamidopropyl)dimethylammonio)propane-1-sulfonate, 4-((3-acrylamidopropyl)dimethylammonio)butane-1-sulfonate, [3-(acryloyloxy)propyl](dimethylammonio)acetate, dimethylaminopropylmethylacrylamide derivatives such as 2-((3-methacrylamidopropyl)dimethylammonio)ethane-1-sulfonate, 3-((3-methacrylamidopropyl)dimethylammonio)propane-1-sulfonate, 4-((3-methacrylamidopropyl) dimethylammonio) butane- 1-sulfonate and [3-(methacryloyloxy)propyl] (dimethylammonio) acetate and mixtures thereof. Preferred hydrophilic monomers are acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid (ATBS) or their mixture, N-vinylpyrrolidone (NVP), MADC, ADC and acrylamide According to one aspect of the invention, the monomers having an ethylenic function in addition to being chosen from hydrophilic monomers as described above can also be chosen from hydrophobic monomers. Hydrophobic monomers, whose partition coefficient Kow is greater than 1, are preferably chosen from the following lists. - (meth)acrylic acid esters with an alkyl, arylalkyl and / or ethoxylated and / or propoxylated chain; (meth)acrylamide derivatives with an alkyl, arylalkyl or dialkyl and / or ethoxylated and / or propoxylated chain; cationic allylic derivatives with an alkyl, arylalkyl or dialkyl and / or ethoxylated and / or propoxylated chain; anionic or cationic hydrophobic derivatives of (meth)acryloyl; and anionic or cationic monomeric derivatives of (meth)acrylamide bearing a hydrophobic chain. The alkyl groups of these hydrophobic monomers are preferably C6 to C24 alkyl groups. The most preferred monomers are bromoalkyl derivatives of methacrylamido dimethyl amino propyl with a C8-C16 alkyl chain and ethoxylated behenyl methacrylate. - n-hexyl (meth)acrylate, n-octyl (meth)acrylate, octyl (meth)acrylamide, lauryl (meth)acrylate, lauryl meth)acrylamide, myristyl (meth)acrylate, myristyl (meth)acrylamide, pentadecyl (meth)acrylate, pentadecyl (meth)acrylamide, cetyl (meth)acrylate, cetyl (meth)acrylamide, oleyl (meth)acrylate, oleyl (meth)acrylamide, erucyl (meth)acrylate, erucyl (meth)acrylamide, and combinations thereof. - LCST (Lower Critical Solution Temperature) and / or UCST (Upper Critical Solution Temperature) monomers or macromonomers. In other words, the hydrophobic character can come from the LCST and / or the properties of the monomers or macromonomers. Patent application WO2020 / 094960 A1 refers to such macromonomers having the LCST property. Among these hydrophobic monomers: - the alkyl groups are preferably C3-C20, more preferably C3-C8. The C6-C20 alkyls are preferably linear alkyls while the C3-C5 alkyls are preferably branched, - the arylalkyl groups are preferably C7-C25, more preferably C7-C15, - the ethoxylated chains preferably comprise 6 to 100 -CH2-CH2-O- groups, more preferably 10 to 40, - the propoxylated chains preferably comprise 1 to 50 groups - CH2-CH2-CH2-O-, more preferably 1 to 20. Preferred hydrophobic monomers are selected from N-isopropylacrylamide; N,N-dimethylacrylamide; N,N-diethyl acrylamide; N-tert-butyl acrylamide; N-vinyl caprolactam; and diacetone acrylamide According to this aspect of the invention, the concentration of hydrophobic monomers is preferably between 0.0001% and 10% mol, more preferably between 0.001% and 5% mol, even more preferably between 0.01% and 3% mol, even more preferably between 0.1 and 2% mol, even more preferably between 0.2 and 1.5% mol, even more preferably between 0.3 and 1.3% mol, the molar percentage being expressed relative to the total number of moles of monomers in the solution (S1). If hydrophobic monomers are added during precipitation polymerization, the hydrophilic monomers will preferably be chosen from anionic and / or non-ionic monomers. The quantities of the different monomer(s) will be adjusted by those skilled in the art so as not to exceed 100 mol% during the preparation of the water-soluble polymers according to the invention. Protein The hybrid polymer (HP) according to the invention is obtained from at least one protein. It can also be obtained from several proteins of different nature. The protein(s) are added to the polymerization feedstock, in the solution (S1) in step (A) of the process described in the present application. The proteins are obtained by conventional methods known to those skilled in the art, for example by dissolving, grinding, screening and classification. The protein(s) may be added in solid or liquid form to the solution (S1). Advantageously, the proteins are added in powder form. According to the invention, the solution (S1) comprises from 0.1% to 40% by weight of proteins, preferably between 1 and 20%, more preferably between 2 and 15% by weight, even more preferably between 5 and 10%. The term "protein" is used herein to include both native (or chemically unmodified) proteins and modified proteins. By "modified proteins" is meant a protein that has undergone one or more pre-treatments. These pre-treatments may be physical by shearing, chemical by acid, alkaline, and / or enzymatic hydrolysis by a protease. Advantageously, native proteins are preferred. The protein(s) according to the invention may be of animal origin; among the animal proteins that may be cited as examples: milk proteins such as B-lactoglobulin, casein, whey; serum proteins such as horse serum; placental proteins; fibrous dermal proteins such as collagen, elastin, silk proteins. The protein(s) according to the invention may be of plant origin, such as corn, wheat, barley and oats, soybeans, peas, for example, glutelin, prolamin, zein, and gluten. Advantageously, plant proteins are chosen from soy proteins, wheat proteins, oat proteins, and pea proteins. Proteins can be obtained from seeds, for example, soybeans, cottonseeds, peanuts, sunflowers, rapeseeds, coconuts, flax seeds, sesame seeds, saflour, peas, beans, and lentils. Other sources of protein are bacteria, fungi, algae and yeasts, e.g. Pseudomonas, Lactobacillus, Penicillium, E.Coli, blue-green algae, green algae, Chlorella, Spirulina and excess yeasts. Preferably, the protein chosen will be casein, whey protein or wheat protein. To convert proteins into a soluble form, digestion by physical, chemical, or enzymatic treatment is often necessary, such as hydrolysis with acid or alkali, fermentation with yeasts, bacteria, or enzymes, extraction methods to remove minor constituents, coagulation from extracts by heating, addition of an electrolyte, pH adjustment, or the addition of precipitants. Pure products can be prepared, for example, by fractional dissolution and precipitation or by dialysis. The protein(s) used according to the invention are soluble or insoluble in water. This has no impact on the viscosifying efficiency of the final hybrid polymer (PH). On the other hand, the choice of protein solubility plays a real interest for the application aspect. If we wish to obtain a viscous gel, particularly for cosmetic applications, we will prefer a translucent gel; a soluble protein will be preferred in this case. If the transparency of the application gel is of little importance, an insoluble protein can be chosen. Proteins may be present as a mixture. This means a mixture containing several proteins originating from the same or different living kingdoms. For example, a mixture containing several proteins of animal origin, or a mixture containing at least one protein of animal origin and at least one protein of plant origin and / or one protein of bacterial origin. Preferably, a single protein is added to the polymerization feedstock of step (A). Polymerization Precipitation polymerization in a solvent medium consists of the polymerization of monomers that are soluble in a solvent while the resulting polymer is insoluble and therefore precipitates in this solvent. Once the polymerization is complete, the polymer appears in the reaction medium in the form of a precipitate. The hybrid polymer (HP) results from the polymerization between at least one monomer comprising at least one unsaturated ethylenic function and at least one protein. According to the present invention, the hybrid polymer (PH) is polymerized by radical precipitation polymerization in a polar solvent medium. For step (A) of the process, a solution (S1) is prepared by including 4 to 40% by weight of at least one monomer having an unsaturated ethylenic function, as described above, 60% to 95% by weight of at least one polar solvent, and 0.1 to 40% by weight of at least one protein; the percentages being given relative to the total weight of (S1), and making a total of 100%. According to a preferred embodiment, the solution (S1) is prepared by first mixing the monomers having an unsaturated ethylenic function and at least one polar solvent, then the protein(s) is added to this mixture. According to the invention, it is possible to use a polar solvent or a mixture of polar solvents. The mixture of polar solvents preferably comprises water and an alcohol or a ketone. The alcohol or ketone is preferably chosen from methanol, ethanol, 1-propanol, 2-propanol, 2-methyl-2 propanol, 1-butanol, 2-butanol, dimethyl ketone, diethyl ketone, pentan-2-one, butanone, tetrahydropyran, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxane, 1,4-dioxane. The mixture of polar solvents is preferably a mixture of protic solvents (proton donors). In a particular embodiment of the invention, the solvent used for the precipitation polymerization is preferably an alcohol comprising 1 to 4 carbons. It is advantageously chosen from methanol, ethanol, propan-1-ol, isopropanol, tert-butanol or mixtures thereof. Preferably, the solvent used is only tert-butanol. The polar solvent mixture preferably contains up to 10% by weight of water, preferably between 1% and 6% by weight of water and even more preferably between 2 and 4% by weight of water. The mixture of polar solvents preferably contains at least 90% by weight of alcohol, more preferably at least 95% by weight, even more preferably at least 97% by weight of alcohol. Thus, preferably, the mixture of polar solvents used for the precipitation polymerization contains less than 10% by weight of water and at least 90% by weight of tert-butanol, preferably from 1 to 5% by weight of water and 99 to 95% by weight of tert-butanol, even more preferably from 2.5% by weight of water and 97.5% of tert-butanol. The polymerization is preferably carried out in the absence of oxygen, according to the present invention. Degassing consists of eliminating the residual oxygen from the solution (S1) obtained at the end of step (A). For this, an inert gas is introduced so as to degas the solution (S1). Inert gas is usually passed through the solution. Suitable inert gases for this purpose are, for example, nitrogen or carbon dioxide. According to one aspect of the invention, surfactants are added in order to stabilize the medium to obtain optimal polymerization conditions. The solution (S1) may comprise at least one surfactant having an HLB (Hydrophilic Lipophilic Balance) of less than 15, preferably between 9-13 in order to stabilize said solution S1 and improve the polymerization. Generally the amount of said surfactant in the solution (S1) is between 0.2 and 20% by weight, preferably from 1 to 10%. The hydrophilic-lipophilic balance (HLB) of a chemical compound is a measure of its hydrophilic and / or lipophilic properties, determined by calculating the values ​​for different regions of the molecule, as described by Griffin in 1949. The surfactant may be non-ionic, anionic, cationic, amphoteric, zwiterrionic, preferably it is a non-ionic surfactant. The surfactant(s) are preferably chosen from ethoxylated surfactants, PEG diacrylates, ethoxylated fatty alcohol ethers, saccharide or polyhydric alcohol esters or betaines, esters prepared from alcohol of the glycerol, diglycerol, triglycerol type or other alcohols such as saccharides like maltinol or sorbitol and mixtures thereof. Advantageously, alkyl polyglucosides are used. According to one aspect of the invention, a crosslinking agent may be included in the solution (S1). The crosslinking agent is advantageously chosen from polyfunctional agents such as methylenebisacrylamide (MBA), ethylene glycol diacrylate, polyethylene glycol dimethacrylate, diacrylamide, cyanomethylacrylate, vinyloxyethylacrylate, vinyloxymethacrylate, triallylamine, trimethylolpropane triacrylate (TMPTA), tetraallylammonium chloride (TAAC), formaldehyde, glyoxal, glycidyl ethers such as ethylene glycol diglycidyl ether, epoxies and mixtures thereof. Preferably, the crosslinking agent is trimethylolpropane triacrylate (TMPTA). The solution (S1) preferably comprises between 500 ppm and 5000 ppm by weight relative to the total weight of the solution (S1) of crosslinking agent, more preferably between 1600 and 3700 ppm, even more preferably between 2500 and 3200 ppm by weight. According to the process of the invention, the polymerization is initiated using free radical initiators with one or more of the above hydrophilic and / or hydrophobic monomers, and the protein(s). As an example of a free radical initiating agent, mention may be made of oxidizing-reducing couples with, among the oxidants, hydroperoxide of cumene or tertiary butylhydroxyperoxide, and among the reducing agents, persulfates such as sodium metabisulfite and Mohr's salt. Azo compounds such as 2,2”-azobis(isobutyronitrile), 2,2*-azobis(2-methylbutyronitrile) and 2,2'-azobis(2-amidinopropane) hydrochloride can also be used as well as peroxidic compounds such as benzoyl peroxide, tert-butyl hydroperoxide or lauroyl peroxide. Degassing is stopped before starting reflux polymerization for several hours, preferably for at least 2 hours. According to the present invention, the radical precipitation polymerization takes place at a temperature between 60 and 85°C at atmospheric pressure. Step (B) of the process consists of initiating the polymerization of the solution (S1) to obtain a dispersion (D1) comprising a hybrid polymer (PH). The polymer (PH) is in the form of a precipitate. Step (C) of the process consists of isolating the hybrid polymer (PH) in particulate form. Said hybrid polymer (PH) can be easily isolated using the usual separation, evaporation and drying methods known to those skilled in the art. The solvent can be extracted by filtration or distillation, advantageously by distillation. The hybrid polymer (HP) is then recovered in particulate form. Generally, the particle size of the hybrid polymer (HP) is advantageously between 5 nm and 5 mm, more advantageously between 50 nm and 5 mm, preferably between 100 nm and 2 mm, even more preferably between 200 um and 1 mm. It may in particular be between 50 nm and 1 mm, or between 500 um and 5 mm, or between 5 um and 1 mm, or even between 100 um and 1 mm. Hybrid polymer The hybrid polymer (HP) has a weight average molecular weight advantageously between 200,000 and 2,000,000 daltons, preferably between 300,000 and 1,500,000 daltons. The hybrid polymer (PH) has a Brookfield viscosity preferably between 1,000 and 100,000 cps, more preferably between 2,500 and 75,000 cps, more preferably between 5,000 and 50,000 cps. The Brookfield viscosity is measured on a 1% by weight polymer solution in water with a Brookfield viscometer RVT module with a rotation speed of 20 rpm. The hybrid polymer (PH) can be linear, structured, or branched. Preferably, the (PH) is structured, i.e. in the form of a star or comb. The hybrid polymer (HP) comprises less than 40% by mass of protein, preferably 10 to 40% by mass of protein, even more preferably 15 to 35% by mass of protein. In the hybrid polymer (HP), the weight ratio between the monomeric units and the protein units is preferably between 50 / 1 and 1 / 5, preferably between 25 / 1 and 1 / 3, more preferably between 10 / 1 and 1 / 2, more preferably between 6 / 1 and 1 / 1. The NMR / DOSY analysis of [Fig.1] allows us to observe that the hybrid polymer (PH), according to the present invention, has at least partial covalent bonds between the protein and the monomers comprising at least one ethylenic function. This analysis allows us to conclude that the hybrid polymer (PH), according to the present invention, is present in a mixture comprising at least: the hybrid polymer (PH) having at least partially covalent bonds between the protein and the monomers comprising at least one ethylenic function, monomers comprising at least one ethylenic function having reacted with each other to form water-soluble polymers and proteins alone. D20 and TSP-d4 are deuterated solvents in NMR. They allow the product to be analyzed to be solubilized without giving off a signal. Indeed, since solvents are generally in very large excess, their peaks would interfere with the reading of the NMR spectrum. Use of hybrid polymer in various applications The invention also relates to the use of the hybrid polymer (HP) as a viscosifying agent in the recovery of hydrocarbons (oil and / or gas); in the drilling and cementing of wells; in the treatment of water in open, closed or semi-closed circuits; in the treatment of fermentation musts in the treatment of sludge; in paper manufacturing; in construction; in the treatment of wood; in the treatment of hydraulic composition (concrete, cement, mortar and aggregates); in the mining industry; in the formulation of cosmetic products; in the formulation of detergents; in the manufacture of textile printing paste; in the manufacture of battery components; in geothermal energy; in the manufacture of hygienic diapers; or in agriculture. Advantageously, the invention relates to the use of the hybrid polymer (PH) according to the invention in the manufacture of cosmetic compositions as a thickening (agent), conditioning (agent), stabilizing (agent), emulsifying (agent), fixing (agent) or film-forming (agent). The invention also relates to the use of the hybrid polymer (PH) as a viscosifying agent for pigmentary composition used in textile printing, said agent comprising at least one hybrid polymer according to the invention. The invention also relates to a method for enhanced recovery of oil or gas by sweeping an underground formation comprising the use of at least one hybrid polymer (HP) according to the invention. The invention also relates to a viscosifying agent, comprising at least one hybrid polymer (PH) according to the invention in a field chosen from hydrocarbon recovery; in well drilling and cementing; in the stimulation of hydrocarbon wells; in paper manufacturing; in construction; in mining industry; in the formulation of cosmetic products; in the formulation of detergents; in textile manufacturing. The invention also relates to an aqueous composition thickened with a hybrid polymer (PH) according to the invention. Another object according to the invention The invention also relates to a hybrid polymer (HP) comprising monomeric units of at least one monomer comprising at least one unsaturated ethylenic function, and protein units, characterized in that the monomeric units and the protein units are partially or totally linked by at least one covalent bond, in that the weight ratio between the monomeric units and the protein units is between 50 / 1 and 1 / 5, preferably between 25 / 1 and 1 / 3, more preferably between 10 / 1 and 1 / 2, more preferably between 6 / 1 and 1 / 1. The invention also relates to a hybrid polymer (PH) obtained by radical polymerization according to a process comprising the following successive steps: (A) Prepare a mixture (M1) comprising at least one monomer comprising at least one unsaturated ethylenic function; and between 0.1% and 50% by weight of at least one protein, optionally at least one solvent; (B) Initiate polymerization in the mixture (M1) to obtain a hybrid polymer (PH); The mixture (M1) preferably comprises between 5% and 90% by weight of at least one monomer comprising at least one unsaturated ethylenic function, more preferably between 10 and 80%, more preferably between 15 and 80%, more preferably between 20 and 80%, more preferably between 25 and 80%, more preferably between 30 and 80%, more preferably between 35 and 75%, more preferably between 40 and 75%, more preferably between 45 and 75%, more preferably between 50 and 70%, more preferably between 55 and 65%. The mixture (M1) preferably comprises between 0.1% and 50% by weight of at least one protein, more preferably between 1 and 40%, more preferably between 3 and 35%, more preferably between 5 and 30%, more preferably between 10 and 25%. The mixture (M1) preferably comprises between 1% and 90% by weight of at least one solvent, more preferably between 5 and 80%, more preferably between 10 and 70%, more preferably between 15 and 60%, more preferably between 20 and 50%. The invention according to this other subject also relates to the use of the hybrid polymer (PH) previously described as a viscosifying agent. It also relates a viscosity modifying agent comprising at least said hybrid polymer (PH). Generally, the polymerization is initiated by free radical initiators as presented in the present application; it can also be initiated by the action of UV radiation. The polymerization is preferably carried out in a temperature range from 20° to 160° C, preferably from 30° to 100° C. The polymerization is preferably carried out in an inert gas atmosphere in the absence of atmospheric oxygen, for example using nitrogen, or carbon dioxide as the inert gas. The reaction temperature and the amount of initiator generally have a significant effect on the polymerization of the hybrid polymer (PH). Advantageously, the monomers comprising at least one unsaturated ethylenic function to be polymerized and the protein are introduced into the reaction vessel at the beginning with at least one polymerization initiator and polymerized by heating to the optimum polymerization temperature. It may be advantageous to use two or more proteins. The order in which the reactants are dosed into the polymerization reactor can be freely changed. If several monomers are used in the graft copolymerization, the individual monomers can be dosed into the polymerization zone successively, or as a mixture, or simultaneously from separate dosing means. For example, it is possible to heat a solution or dispersion of the protein in the reactor to the required polymerization temperature and add the monomers and initiators continuously or in batches. Likewise, the pH of the reaction medium can have an influence on the hybrid polymer (PH). Acidic or basic monomers can be used in the form of the corresponding salts. For example, acrylic acid is used in the form of a free acid or in the form of an alkali salt. The polymerization can be carried out in a pH range from 1 to 14, preferably from 6 to 12. By changing the pH, it is possible, for example, to precipitate the graft copolymers from solutions. This possibility can be used during the processing, purification and isolation of graft copolymers. Proteins used in graft copolymerization can be chemically modified in various ways before or after graft polymerization. The DOSY experiment, an NMR method, allows the separation of species present according to their diffusion coefficients in a solvent and allows the analysis of complex mixtures and the detection of traces. The aim of this experiment is to demonstrate that there is at least one covalent bond between monomers comprising at least one ethylenic function and a protein. The DOSY experiment consists of recording proton spectra by varying the G-force of the applied gradients and thus the scattering force. A linear increase in gradient intensity will result in an exponential decrease in NMR signal intensity. The DOSY experiment gives a two-dimensional map. The 2nd dimension F2 of the DOSY corresponds, after processing by the Fourier transform, to the 1H dimension. The 1st dimension F1 corresponds to the decrease of the NMR signal as a function of the applied gradient force. After processing the F2 dimension, the diffusion coefficient is extracted and a DOSY map is obtained. If the two matrices have an identical diffusion coefficient, this means that the two matrices have the same hydrodynamic radius, and are therefore grafted. On the other hand, if the two matrices have two different diffusion coefficients, this means that they are free from each other. In Figures 1 and 2, NMR analyses were performed on a Bruker 400 MHz ASCEND (TM) Avance III HD instrument equipped with a 10 mm BBO 400 MHz ZG radiant probe. TSP-d4 is deuterated sodium trimethylsilylpropanoate. Conclusion : The diffusion coefficient of the signals related to the protein in the hybrid polymer differs from that of the protein alone (isolated). NMR / DOSY (Diffusion Order Spectroscopy) analysis of samples on pure products (products obtained after polymerization, and without additional treatment) showed that the protein grafts onto the ATBS and that, subsequently, the unsaturated monomer also grafts onto the oligomer. Examples The following examples best illustrate the advantages of the invention in a clear and non-limiting manner. I - Synthesis of hybrid polymer according to the invention Example 1: PHA = ATBS homopolymer + casein 450 g of tert-butanol comprising 2.5% by mass of water are introduced into a jacketed reactor equipped with a stirring blade. 2-Acrylamido-2-methylpropane sulfonic acid (ATBS) is added, with stirring. The medium is bubbled with gaseous ammonia for 30 minutes, while checking that the pH does not exceed 7. The preparation is degassed in the reactor by injecting nitrogen for 30 minutes. During this time, the medium is gradually heated to 55 °C. Trimethylolpropane triacrylate (TMPTA, crosslinking / branching agent) is then added, followed by casein (milk protein) and the temperature of the medium is brought to 70 °C using a thermostatically controlled bath. The polymerization reaction is initiated by adding 0.6 g of di- lauroyl. Polymerization starts quickly and reaches a maximum exothermicity. Once the maximum temperature is reached, the medium is placed at reflux for 2 hours. The presence of a white precipitate is observed in the solvent (tert-butanol + 2.5% by mass of water). This white precipitate corresponds to the hybrid copolymer of the invention. The solvent is then removed using a rotary evaporator with oil heated to 90°C and under a reduced pressure of 100 mbar. The copolymer obtained is then dried overnight at 70°C. Table 1 below summarizes the composition of the PHA polymer as well as its viscosity. Brookfield viscosity is measured on a 1% by weight polymer solution in water with a Brookfield RVT module viscometer with a rotation speed of 20 rpm. [Tables 1] pe [ATBS- [AA] |[AA-NH |[TMPTA] sn Viscosity pr | hybrid |NH4] (Jweight |4] (%weight) |(%weight) |Brookfield (weight |) {%weight RVT 20 ) ) rpm @ 1% | water (cP) [PH [142 jo jop Jos 67 [11000 |Casein | Example 2: PHB = ATBS copolymer + Acrylic acid + casein The procedure is identical to that in the example of hybrid polymer 1, except that the monomers used are 2-acrylamido-2-methylpropane sulfonic acid (ATBS) and acrylic acid (30 / 70 mol %). The polymerization reaction is initiated by adding 0.4 g of 2,2'-Azobis(2-methylpropionamidine)dihydrochloride. The polymerization starts quickly and reaches a maximum exothermicity. Once the maximum temperature is reached, the medium is placed at reflux for 2 hours. Hybrid polymer 2 is recovered in the same way as before. The amounts of protein as well as crosslinking agent can be modulated to achieve the desired viscosity and naturalness / biodegradability target. Table 2 below summarizes the composition of the PHB polymer as well as its viscosity. [Tables 2] [PES [142 00 — |00 Jos |67 40000 Protein | serum Example 3: PHc = PH, without crosslinker 450 g of tert-butanol comprising 2.5% by mass of water are introduced into a jacketed reactor equipped with a stirring blade. 2-Acrylamido-2-methylpropane sulfonic acid (ATBS) is added, with stirring. The medium is bubbled with gaseous ammonia for 30 minutes, while checking that the pH does not exceed 7. The preparation is degassed in the reactor by injecting nitrogen for 30 minutes. During this time, the medium is gradually heated to 55 °C. Micellar casein (milk protein) is then added and the temperature of the medium is brought to 70 °C using a thermostatic bath. The polymerization reaction is initiated by adding 0.6 g of di-lauroyl peroxide. The polymerization starts quickly and reaches a maximum exothermicity. Once the maximum temperature is reached, the medium is placed at reflux for 2 hours. The presence of a white precipitate is observed in the solvent (tert-butanol + 2.5% by mass of water). This white precipitate corresponds to the hybrid copolymer of the invention. The solvent is then removed using a rotary evaporator with oil heated to 90°C and under a reduced pressure of 100 mbar. The copolymer obtained is then dried overnight at 70°C. Table 3 below summarizes the composition of the PHc polymer as well as its viscosity. [Tables 3] pe [ATBS- [AA] | |[AA-NH|[TMPTA] pre Viscosity pr | hybrid |NH4] (Rweight |4] (%weight) |(Yweight) |Brookfield (%weight |) (%weight RVT 20 ) ) rpm @ 1% | water (cP) |PEts |142 |o0 |o0 |o2 |6.7 |15600 Protein | serum Example 4: Synthesis of PHp to PHo hybrid polymers The PH, PHo hybrid copolymers are manufactured according to the protocol of Example 1. The polymerizations are carried out at 15% by mass of active material relative to the reaction medium. The quantities of the different monomers are adjusted in order to obtain the proportions indicated in Table 4 below for each example. ae [AA-NH|[TMPTA] ve Viscosity pro | e H4](% |(% 4] (% (% wt) |(% wt) |Brookfield hybrid |wt) wt) |wt) RVT 20 rpm @ 1% | water (cP) PH: [9.5 36 |44 |04 78 29250 serum = 88 33 ja0 los 14.6 9100 [Hs |ss 33 |40 jo 14.6 14250 [Ps 00 85 |104 |o2 8.5 [11100 [00 85 |104 lo2 8.5 24500 Ps jo0 85 |104 lo2 8.5 37000 [PH [142 Joo joo Jos 67 12500 [Protein | wheat [PL 142 Joo Jo os Jea 6900 Gluten PH, |142 joo joo oz 67 6900 PH, [142 Joo joo 03 67 33250 [PH 142 oo Joo los 67 7500 He [142 [oo joo jo I 7500 Hrvut of wheat [Table 4] II - Application examples Example 5: Textile application: Pigment printing paste prepared in aqueous solution. A pigment printing paste is produced at a viscosity of 6,500 cps, measured with a Brookfield module RV viscometer at a speed of 20 revolutions per minute at 25°C. The printing paste comprises: 12% of HELIZARIN 83 Liq C binder from ARCHROMA (styrene / acrylic copolymer) or equivalent and 1.5% of a blue pigment dispersion PIGMACOLOR BLUE from KEMITEX. The whole is mixed and then the hybrid polymer D from Example 1, as a thickener, is added with stirring to thicken the printing paste. The quantities of hybrid polymer D, as well as the other components, are adjusted in order to to obtain the target viscosity of 6500 cps. The hybrid polymer D according to example 1 as well as two comparative examples outside the invention are presented in table 5 below: a thickening acrylic inverse emulsion and a thickening acrylic polymer obtained by precipitation polymerization (PA-PPP). [Tables 5] | Name PH, Inverse emulsion (invention) (counterexample) / |8 13.5 (PA-PPP) (counterexample | ) 6 Consumption in # | [13.5 I kg Quantity of thickener |2.4 Jos | 1.8 (g) Water (g) 257.1 255.45 257.7 Binder (g) 36 36 36 |Pigment © 4.5 4.5 4.5 Brookfield viscosity |6,500 CP 6,500 cP 6,500 cP RVT 50 rpm The pastes produced are evaluated in terms of application performance of color yield, melting and crossing which are the major control parameters in screen printing. The printing system is a FAM-R type printing table - STORK Company; the magnetic transfer squeegee is a 10 mm diameter and 30 cm long model and the printing frame is a 125 mesh opening model. Three types of fabric are used to characterize the different parameters: - A 100% cotton canvas; - A 100% polyester satin and - A 97 / 3 cotton elastane satin. After printing, the design is fixed by passing it through a dryer for 3 minutes at 160°C. The results are assessed comparatively with respect to each other by the judgment of the person skilled in the art. These results are recorded in Table 6 below. [Tables 6] Benchmark PA- | PPP Hybrid Polymer | Benchmark inverse D emulsion | = | Reference Reference Reference Yield |= [Reference | - color Penetration |= Reference |- Melting |= Reference |- = : performance identical to the “inverse emulsion benchmark” reference Reference: performance of the “inverse emulsion benchmark” reference - : performance inferior to the “inverse emulsion benchmark” reference -- : performance much inferior to the “inverse emulsion benchmark” reference Acrylic polymers obtained by precipitation polymerization are known to have application performances inferior to the benchmarks obtained by inverse emulsion. For this reason, thickeners in inverse emulsions are generally preferred in the world of screen printing. Surprisingly, as can be seen, the hybrid polymer D obtained by precipitation polymerization according to the invention has printing performances significantly superior to those of the acrylic benchmark (PA-PPP) obtained by a similar polymerization process. Furthermore, the hybrid polymer D equals the benchmark obtained by inverse emulsion while having a lower consumption, which represents a definite advantage. Example 6: Oil application: A PHp hybrid polymer is manufactured according to the process according to example 1. Its composition and characteristics are specified in table 7 below. [TMPTA] {% weight) Polymer |[ATBS-NH4] [AM] (% c (% wt) wt) hybrid Polymer |[ATBS-NH4] [AM] (% |[TMPTA] [Serum Protein] |Brookfield c (% wt) wt) {% wt) |(% wt) RVT 30 rpm hybrid @ 0.5% water (cP) |P5, [122 47 0.00 83 41 [Table 7] Test for drilling application: In a mixer are added 600g of Grade G cement, 4.5g of PHop hybrid polymer, 1.8g retardant (CR104), 1.2g dispersant (CD-1B), 264g deionized water. The whole is mixed for 15 seconds at speed 4 00Orpm then 35 seconds at 12 00Orpm before being placed for 20 minutes in a consistometer at 85 °C. The fluid loss is then studied using an HTHP filter press at 85 °C, under a pressure of 1000 psi for a period of 30 minutes. In the case of the benchmark, the fluid loss is 32 mL. In the case of the hybrid polymer, it is 38 mL. The latter is in good agreement with the required properties. Example 7: Cosmetic application: The following compositions comprising hybrid polymer C or I, which are hybrid polymers obtained according to Example 1. Table 8 below details an example of a cosmetic formulation comprising 1% by weight of hybrid polymers C and I. [Tables 8] |5.0 [50 [Hybrid Polymer C Hybrid Polymer I Brookfield Viscosity RVT |15,600 cP 24,500 cP 20 rpm 1% aq. Cosmetic formula studied Compounds Mass (g) Water 87.75 219.4 Glycerin 2 5.0 |Polymer | 1 2.5 Natura Tec 3 7.5 Ultradeel AL Natura Tec | |50 Abysoft Caprylic / Capri |2 [5 c Triglyceride Almond Oil |2 [5 soft Tocobiol C 0.05 Glydant plus |0.2 liquid 250 g Total 100 Final Analyses pe 700 — |250g Final Analysis |Cream Appearance Glossy, fluid, smooth cream |Light creamy cream Emulsifying Properties Emulsifying Properties Viscosity Brookfield RVT |16,600 cP 22,000 cP 20 rpm = RER = The cosmetic composition comprising the hybrid polymers according to the invention meets the technical cosmetic requirements with a target viscosity obtained.

Claims

Claims

1. Hybrid polymer (PH) in particulate form obtained by a process of radical polymerization by precipitation according to the following steps following provisions: (A) Prepare a solution (S1) comprising: - 50 to 95% by weight of at least one polar solvent, - 4 to 40% by weight of at least one monomer comprising at least one unsaturated ethylenic function, and - 0.1 to 40% by weight of at least one protein; the percentages being given in relation to the total weight of (S1), and making a total of 100%; (B) Initiate polymerization in solution (S1) to obtain a dispersion (D1) comprising at least one hybrid polymer (PH); (C) Isolate the hybrid polymer (PH), in particulate form, from the dispersion (D1).

2. Hybrid polymer (PH) according to claim 1, characterized in that the solution (S1) is made by first mixing the monomers having at least one unsaturated ethylenic function and at least one minus a polar solvent, then the following is added to this mixture: proteins.

3. Hybrid polymer (PH) according to one of the preceding claims, ca- characterized in that the monomer(s) comprising at least one unsaturated ethylenic function of step (A) are hy- monomers drophiles.

4. Hybrid polymer (PH) according to claim 3, characterized in that the or the hydrophilic monomers are non-ionic and / or anionic, such that when they are non-ionic they are chosen from acrylamide, methacrylamide, N,N-dimethylacrylamide, N- vinylformamide, N-vinyl acetamide, N-vinylpyridine, N- vinylpyrrolidone, acryloyl morpholine (ACMO), diacetone acrylamide, or a mixture of these monomers, and when they are anionic they are chosen from the group including monomers having a carboxylic acid function and their salts, the monomers having a sulfonic acid function and their salts or monomers having a phosphonic function and their salts, or a mixture of these monomers.

5. Hybrid polymer (PH) according to one of the preceding claims, ca- characterized in that the solution (S1) comprises from 10 to 30% by weight of at least minus one hydrophilic monomer; the percentage being given in relation to the total weight of the solution (S1).

6. Hybrid polymer (PH) according to one of the preceding claims, ca- characterized in that in step (A), the solution (S1) is prepared from of a mixture of polar solvents, and at least one monomer comprising at least one unsaturated ethylenic function, said mixture of polar solvents comprising 0.5% to 10% by weight of water, and at less than 90% by weight of an alcohol comprising 1 to 4 carbons.

7. Hybrid polymer (PH) according to claim 6, characterized in that the alcohol containing | 4 carbons is tert-butanol.

8. Hybrid polymer (PH) according to one of claims 6 or 7, ca- characterized in that the mixture of polar solvents comprises from 1 to 5% by weight of water and 95 to 99% by weight of tert-butanol.

9. Hybrid polymer (PH) according to one of the preceding claims, ca- characterized in that the protein is chosen from the original proteins animal, vegetable and / or their mixtures.

10. Hybrid polymer (PH), according to one of the preceding claims, ca- characterized in that the protein is a casein, a whey protein, a wheat protein or mixtures thereof.

11. Hybrid polymer (PH), according to one of the preceding claims, ca- characterized in that said hybrid polymer (PH) comprises mono- units meric of at least one monomer comprising at least one function unsaturated ethylenic, and protein units, said mono- units meric and said protein units being partially or to- firmly linked by at least one covalent bond.

12. Hybrid polymer (PH), according to one of the preceding claims, ca- characterized in that the hybrid polymer (PH) has a molecular weight weight average between 200,000 and 2,000,000 daltons.

13. Use of the hybrid polymer (PH) according to one of claims 1 to 12 as a viscosifying agent in hydrocarbon recovery; in well drilling and cementing; in well stimulation hydrocarbons; in paper manufacturing; in construction; in the mining industry; in the formulation of cosmetic products; in the formulation of detergents; or in the manufacture of textiles.

14. Viscosifying agent comprising at least one hybrid polymer (PH) according to one of claims 1 to 12 in the recovery of hydrocarbons; in the drilling and cementing of wells; in the sti- hydrocarbon well development; in papermaking; in construction; in the mining industry; in the formulation of cosmetic products; in the formulation of detergents; or in the textile manufacturing.

15. Aqueous composition thickened with a hybrid polymer (PH) according to one of claims 1 to 12.