Process for preparation by reverse radical polymerization emulsion

Abstract

The present invention relates to a process for preparing a water-soluble block polymer by radical polymerization using reversible addition-fragmentation chain transfer in reverse emulsion comprising the addition of a hydrophilic phase during the polymerization step.

Description

Title of the invention: Process for preparation by inverse emulsion radical polymerization. Technical field of the invention

[0001] The present invention relates to a process for preparing a water-soluble block polymer by radical polymerization by reversible addition-fragmentation chain transfer in inverse emulsion. Prior state of the art

[0002] Block polymers are polymers composed of at least two different monomer blocks. To obtain them, it is common practice to polymerize a first phase of monomers and then add a second phase of a different monomer. There are various techniques for obtaining these polymers, such as controlled radical polymerization, template polymerization, polymerization on a macromonomer, functionalization of prepolymers allowing the formation of a covalent bond between said prepolymers, or the use of two monomers having a reactivity ratio largely in favor of one of the two.

[0003] High molecular weight block polymers are impossible to prepare in solution or only at very low concentrations. Indeed, the high viscosity resulting from polymer formation prevents the homogeneous incorporation of a second hydrophilic phase, leading to compositional drifts in the final polymer and a limited molecular weight.

[0004] Reverse emulsion polymerization (water-in-oil) is known to overcome problems related to the viscosity of the polymerized solution; it consists of dissolving the monomers in an aqueous solvent, emulsifying the monomer solution in an oil to obtain a water-in-oil emulsion, and carrying out the polymerization of the monomers in the dispersed phase of the emulsion.

[0005] US patents US4152200, US4191645, US4217262, and US5171783 disclose the preparation of a polymer by means of a reverse emulsion process comprising the progressive addition, during polymerization, of a hydrophilic phase comprising monomers. This results in poor incorporation of the hydrophilic phase into the reverse emulsion, leading to a plurality of droplets having different monomeric compositions, which in turn leads to deviations in the composition of the desired polymer.

[0006] The Applicant has developed a radical polymerization process enabling the production of inverse emulsions with good incorporation of the hydrophilic phase, This allows access to high molecular weight and high concentration block polymers.

[0007] Without wishing to be linked to any theory, the Applicant suggests the possibility that the combination between (1) a control agent used for reversible addition-fragmentation chain transfer polymerization, (2) the size of the polymer chains of the prepolymer formed in a first step and (3) the control of the viscosity of the hydrophilic phase of the reverse emulsion, allows better integration of a second hydrophilic phase into the first hydrophilic phase of the reverse emulsion already formed.

[0008] The process of the invention is based on a principle of environmental awareness and the impact of industry and humankind on the planet. This process makes it possible to obtain high molecular weight block polymers at high concentrations, thus improving the yield compared to conventional polymerization, and the use of an inverse emulsion reduces the amount of energy associated with homogenizing the less viscous medium, thereby reducing the amount of greenhouse gas emissions such as CO2 associated with the production of these polymers. Description of the invention

[0009] The invention relates to a process for preparing a water-soluble block polymer by radical polymerization using reversible addition-fragmentation chain transfer in inverse emulsion, comprising the following steps: a) Mixing a hydrophilic phase PHI and a lipophilic phase PLI under stirring to form a reverse emulsion EMU, the hydrophilic phase PHI comprising at least one hydrophilic solvent SH1, at least one monomer A and at least one water-soluble control agent of formula (I):

[0010] [Chem.l]

[0011] in which - Z represents O, S or NR3; - Ri, R2, and R3, whether identical or different, represent: * a group (i), alkyl, acyl, alkenyl or alkynyl, possibly substituted, or * a carbon ring (ii), saturated or unsaturated, possibly substituted or aromatic, or * a heterocycle (iii), saturated or unsaturated, possibly substituted or aromatic, these groups and rings (i), (ü) and (iii) can be substituted by substituted aromatic groups or by alkoxycarbonyl or aryloxycarbonyl groups (-COOR), carboxy (-COOH), acyloxy (-O2CR), carbamoyl (-CON(R)2), cyano (-CN), alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl, phthalimido, maleimido, succinimido, amidino, guanidimo, hydroxy (-OH), amino (-N(R)2), halogen, allyl, epoxy, alkoxy (-OR), S-alkyl, S-aryl, groups exhibiting hydrophilic or ionic character such as alkali salts of carboxylic acids, alkali salts of sulfonic acid, polyalkylene oxide chains (POE, POP), cationic substituents (quaternary ammonium salts); - R representing an alkyl or aryl group in CrC2o; - R3 can also represent a hydrogen atom; - Q is a linear or structured polymeric chain comprising n identical or different hydrophilic monomers comprising at least one ethylenic function; - n is an integer between 0 and 500, advantageously between 1 and 500, more advantageously between 1 and 100, Q being a single bond between the sulfur atom and the R2 group when n is equal to 0.1a lipophilic PLI phase comprising at least one lipophilic solvent and at least one water-in-oil emulsifying agent; b) PI polymerization, in the presence of at least one initiator, of at least monomer A of the inverse emulsion EMU to form a prepolymer PP1 having a molecular weight between 10,000 and 3,000,000 g / mol and having a viscosity between 400 and 100,000 cps; c) Addition and mixing to the reverse emulsion EMU, of a hydrophilic phase PH2 comprising at least one hydrophilic solvent SH2, at least one monomer B to form a reverse emulsion EMI2; the hydrophilic phase PH2 and the hydrophilic phase PHI having distinct compositions, d) Polymerization P2, in the presence of at least one initiator, of at least monomer B on the prepolymer PP1 in order to form a water-soluble block polymer.

[0012] The present invention also relates to a water-soluble block polymer obtained according to this process.

[0013] The present invention also relates to the use of this water-soluble block polymer in: hydrocarbon (oil or gas) recovery; well drilling; well cementing; hydrocarbon (oil or gas) well stimulation, for example hydraulic fracturing, conformance drilling, diversion drilling; open, closed, or semi-closed water treatment; fermentation must treatment; sludge treatment; construction; paper or cardboard manufacturing; the battery industry; wood processing; hydraulic composition processing (concrete, cement, mortar, and aggregates); the mining industry; and the formulation of cosmetic products; detergent formulation; textile manufacturing; geothermal energy; sanitary diaper manufacturing; or agriculture.

[0014] Finally, the present invention also relates to the use of this water-soluble block polymer as a flocculant, coagulant, binding agent, fixing agent, viscosity reducing agent, thickening agent, absorbing agent, friction reducing agent, draining agent, charge retention agent, dehydrating agent, conditioning agent, stabilizing agent, film-forming agent, sizing agent, superplasticizing agent, clay inhibitor or dispersant. Description of the invention

[0015] By "polymer" is meant a polymer obtained from at least two different monomers, it may be a copolymer, a terpolymer or a polymer prepared from more than three different monomers.

[0016] By “block polymer”, we mean di-blocks, tri-blocks or multi-blocks.

[0017] By "hydrophilic monomer" is meant a monomer which has a coefficient octanol / water partition coefficient, Kow, less than or equal to 1, in which the partition coefficient Kow is determined at 25 °C in an octanol / water mixture having a volume ratio of 1 / 1, at a pH between 6 and 8.

[0018] By "hydrophobic monomer" is meant a monomer which has an octanol / water partition coefficient, Kow, greater than 1, in which the partition coefficient Kow is determined at 25°C in an octanol / water mixture having a volume ratio of 1 / 1, at a pH between 6 and 8.

[0019] The octanol / water partition coefficient, Kow, represents the ratio of the concentrations (g / L) of a monomer between the octanol phase and the aqueous phase. It is defined as follows:

[0020] [Math.l] \monomer\ . , rr __ L ■■vctanm — [nwn&nère]^

[0021] By "water-soluble polymer" or "water-soluble control agent" is meant a polymer or a control agent which gives an aqueous solution free of insoluble particles when dissolved under stirring at 25°C and with a concentration of 10 gL 1 in deionized water.

[0022] By "X and / or Y" means "X", or "Y", or "X and Y".

[0023] Also part of the invention are all possible combinations of the various disclosed embodiments, whether preferred or given by way of example. Furthermore, where ranges of values ​​are indicated, the bounds are part of those ranges. The disclosure also includes all combinations of the bounds of those ranges of values. For example, the ranges of values ​​“1-20, preferably 5-15”, imply the disclosure of the ranges “1-5”, “1-15”, “5-20” and “15-20” and the values ​​1, 5, 15 and 20.

[0024] A "water-in-oil emulsifying agent" is defined as a compound capable of emulsifying water in oil, and an "oil-in-water emulsifying agent" is a compound capable of emulsifying oil in water. Generally, a water-in-oil emulsifying agent is considered to be a surfactant with an HLB strictly less than 8, and an oil-in-water emulsifying agent is considered to be a surfactant with an HLB greater than or equal to 10. A surfactant with an HLB between 8 and 10 is considered a wetting agent. Those skilled in the art may refer to K. Holmberg's "Handbook of Applied Surface and Colloid Chemistry," Chapter 11, if necessary.

[0025] The hydrophilic-lipophilic equilibrium (HLB) of a chemical compound is a measure of its hydrophilic and / or lipophilic properties, determined by calculating the values ​​for the different regions of the molecule, as described by Griffin in 1949.

[0026] In the present invention, we have adopted Griffin's method based on calculating a value based on the chemical groups of the molecule. Griffin assigned a dimensionless number between 0 and 20 to provide information on the solubility of water and oil.

[0027] The HLB value of a substance having a total molecular mass M and a hydrophilic part of a molecular mass Mh is given by: HLB = 20 (Mh / M).

[0028] The molecular weight is advantageously determined from the intrinsic viscosity of the polymer. The intrinsic viscosity can be measured by methods known to those skilled in the art and can be calculated from the reduced viscosity values ​​for different polymer concentrations by a graphical method consisting of plotting the reduced viscosity values ​​(ordinate axis) against the concentration (abscissa axis) and extrapolating the curve down to zero concentration. The intrinsic viscosity value is plotted on the ordinate axis or using the least squares method. The molecular weight can then be determined by the Mark-Houwink equation: [î]] = KM “ [r|] 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, are represents the Mark-Houwink coefficient. K and a depend on the particular polymer-solvent system.

[0029] The apparent viscosity of the PP1 prepolymer of the hydrophilic phase of the EMU inverse emulsion is measured according to the following method: - precipitation in acetone of the prepolymer PP1, under agitation (1000 rpm (rotations per minute)); - recovery by filtration of the PP1 prepolymer in solid form; - drying of the PP1 prepolymer in solid form in an oven at 30 °C for 24 hours; - re-dissolving the dried PP1 prepolymer in a 7% by weight sodium chloride solution in water; - measurement of the apparent viscosity of the PP1 prepolymer solution using a Brookfield LVT or LVD viscometer at a temperature of 25 °C. Polymer preparation process

[0030] The polymerization is a radical polymerization. Radical polymerization includes polymerization using UV, azo, thermal, or redox salt initiators.

[0031] Polymerization is carried out by reversible addition-fragmentation chain transfer polymerization (RAFT).

[0032] RAFT is a reversible deactivation radical polymerization (RDRP) technique combining both the ease of implementation of conventional radical polymerization and the living nature of ionic polymerization.

[0033] RAFT relies on a reversible activation-deactivation equilibrium between a dormant species and an active species (a growing macroradical). This activation-deactivation process allows the chains to grow at the same rate until the monomer is completely consumed, making it possible to control the molecular weights of the polymers and obtain narrow molecular weight distributions. This also minimizes compositional heterogeneity. The reversible deactivation of the growing chains minimizes irreversible termination reactions. The vast majority of the polymer chains remain in a dormant state and are therefore reactivated. It is then possible to functionalize the chain ends to initiate other polymerization modes or to create chain extensions. This mechanism allows access to high molecular weights, controlled compositions, and architectures.

[0034] Controlled radical polymerization therefore has the following distinctive features: 1. the number of polymer chains is fixed throughout the reaction, 2. the polymer chains all grow at the same rate, resulting in: * a linear increase in molecular weights, * a narrower distribution of molecular weights, 3. The average molecular weight is controlled by the monomer / controlling agent molar ratio

[0035] The controlled nature of the chain is all the more pronounced when the rate of reactivation of the chains into radicals is much greater than the rate of chain growth (propagation). However, in some cases, the rate of reactivation of the chains into radicals is greater than or equal to the rate of propagation. In these cases, conditions 1 and 2 are not observed and, consequently, control of the molecular weights is not possible.

[0036] Reversible addition-fragmentation chain transfer polymerization requires the use of a control agent.

[0037] The control agent according to the invention is typically a thiocarbonate derivative such as a dithiocarbonate (or xanthate) or trithiocarbonate or a dithiocarbamate derivative described by formula (I).

[0038] In the context of the invention, the water-soluble control agent has the formula (I):

[0039] [Chem.l] (I)

[0040] in which - Z represents O, S or NR3; - Ri, R2, and R3, whether identical or different, represent: * a group (i), alkyl, acyl, alkenyl or alkynyl, possibly substituted, or * a carbon ring (ii), saturated or unsaturated, possibly substituted or aromatic, or * a heterocycle (iii), saturated or unsaturated, possibly substituted or aromatic, these groups and rings (i), (ii) and (iii) being able to be substituted by substituted aromatic groups or by alkoxycarbonyl or aryloxycarbonyl groups (-COOR), carboxy (-COOH), acyloxy (-O2CR), carbamoyl (-CON(R)2), cyano (-CN), alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl, phthalimido, maleimido, succinimido, amidino, guanidimo, hydroxy (-OH), amino (-N(R)2), halogen, allyl, epoxy, alkoxy (-OR), S-alkyl, S-aryl, groups exhibiting a hydrophilic or ionic such as alkali salts of carboxylic acids, alkali salts of sulfonic acid, alkylene polyoxide chains (POE, POP), cationic substituents (quaternary ammonium salts); - R representing an alkyl or aryl group in Ci-C20; - R3 can also represent a hydrogen atom; - Q is a linear or structured polymer chain comprising n identical or different hydrophilic monomers, each comprising at least one ethylenic function; - n is an integer between 0 and 500, advantageously between 1 and 500, more advantageously between 1 and 100. When n is equal to 0, Q is a single bond between the sulfur atom and the R2 group. The monomer(s) used to form Q are advantageously chosen from among the same hydrophilic monomers used to form the water-soluble block polymer and described later in the description.

[0041] Q is typically a linear or structured polymer chain, preferably linear.

[0042] In the functions N(R)2, the two groups R can be identical or different from each other.

[0043] According to a preferred mode, the water-soluble control agent of formula (I) is a dithiocarbonate or xanthate derivative in which Z = O.

[0044] According to another preferred embodiment, the water-soluble controlling agent has formula (I) in which: -Z = O; - Q is a linear or structured polymer chain obtained from 0 to 100 monomers comprising at least one non-ionic hydrophilic monomer and / or at least one anionic hydrophilic monomer and / or at least one cationic hydrophilic monomer.

[0045] According to another preferred embodiment, the water-soluble controlling agent has formula (I) in which: -Z = O; - Q is a linear or structured polymer chain obtained from 0 to 100 monomers comprising at least one non-ionic hydrophilic monomer and / or at least one anionic hydrophilic monomer and / or at least one monomer containing an LCST group.

[0046] According to another preferred mode, the water-soluble control agent has formula (I) in which Z = O, Q is a polymeric chain of an acrylamide monomer, n is an integer between 1 and 100, preferably between 2 and 50, represented by formula (II):

[0048] In another preferred mode, the controlling agent is a trithiocarbonate of formula (I) in which Z = S.

[0049] In another preferred mode, the control agent of formula (I) is a trithiocarbonate in which Z = S is represented by formula (III):

[0050] [Chem.3] (III)

[0051] in which Q is a single bond between the sulfur atom and the group R2= -CH(CH3)2-CO2R3 and: - the R3s are identical or different, independently representing an H or a CH3 or a monovalent or divalent cation, advantageously chosen from the cations of alkali metals (Li, Na, K...), alkaline earth metals (Ca, Mg...) or ammonium ion (for example the ammonium ion or a tertiary ammonium). Preferably it is sodium.

[0052] In another preferred mode, the controlling agent is a trithiocarbonate of the following formula (IV):

[0053] [Chem.4]

[0054] in which Z=S, Q is a polymeric chain of an acrylamide monomer and: - the R3s are identical or different, independently representing an H or a CH3 or a monovalent or divalent cation, advantageously chosen from among the metal cations alkali metals (Li, Na, K...), alkaline earth metals (Ca, Mg...) or ammonium ion (for example the ammonium ion or a tertiary ammonium), preferably sodium; - n and n' are independent integers between 1 and 100, preferably between 1 and 50.

[0055] In another preferred mode, the control agent of formula (I) is a trithiocarbonate in which Z = S, n = 0, R2 = -CH(CH3)COOR3 and Ri = -(CH2)2CO2R3 represented by the following formula (V):

[0056] [Chem.5]

[0057] and in which Q is a single bond between the sulfur atom and the R2 group: - the R3s are identical or different, independently representing an H, a CH3 or a monovalent or divalent cation, advantageously chosen from the cations of alkali metals (Li, Na, K...), alkaline earth metals (Ca, Mg...) or ammonium ion (for example the ammonium ion or a tertiary ammonium). Preferably it is sodium.

[0058] In another preferred mode, the control agent is of formula (I) in which Z = S, and Q is a polymeric chain of an acrylamide monomer represented by formula (VI):

[0059] [Chem.6]

[0060] and the R3s, identical or different, independently represent an H, a CH3 or a monovalent or divalent cation, advantageously chosen from alkali metal cations (Li, Na, K...), alkaline earth metal cations (Ca, Mg...) or ammonium ion (for example the ammonium ion or a tertiary ammonium), preferably sodium; and - n is an integer, between 1 and 100, preferably between 1 and 50. Reverse emulsion polymerization

[0061] The polymerization is carried out in an inverse emulsion. The term "inverse emulsion" refers to both inverse emulsions and inverse microemulsions. These are water-in-oil emulsions in which the hydrophilic phase is dispersed in the lipophilic phase in the form of drops or droplets.

[0062] An inverse emulsion consists of a two-phase medium. It can be unstable in the absence of a surfactant (surfactants include water-in-oil and oil-in-water emulsifying agents). Upon stirring, hydrophilic phase particles are observed dispersed in a lipophilic phase, exhibiting a wide size distribution around an average that can be on the order of micrometers. During reverse emulsion polymerization, the monomer is dispersed in the large droplets of the emulsion (diameter: approximately 1 µm to 10 µm) as well as in the small emulsifier micelles (diameter approximately 5 to 10 nm).

[0063] This polymerization technique is well known to those skilled in the art. It consists of emulsifying a hydrophilic phase comprising one or more monomers in a lipophilic phase. This emulsification is achieved using a water-in-oil emulsifying agent.

[0064] Step a)

[0065] Step a) includes mixing a hydrophilic phase and a lipophilic PLI phase.

[0066] The hydrophilic solvent SH1 of the hydrophilic phase can be any solvent capable of solubilizing a hydrophilic monomer. Advantageously, it is water.

[0067] The quantity of monomer A in the hydrophilic phase PHI is advantageously between 10 and 50% by weight relative to the total weight of the hydrophilic phase PHI, preferably between 15 and 45% by weight, more preferably between 20 and 40% by weight.

[0068] The amount of monomer A in the hydrophilic phase PHI is advantageously between 0.1 and 99.9 mol% relative to the total amount of monomer of the water-soluble block polymer, preferably between 1 and 99 mol%, more preferably between 5 and 95 mol%, more preferably between 10 and 90 mol%, more preferably between 15 and 80 mol%, more preferably between 20 and 50 mol%.

[0069] The amount of water-soluble control agent in the hydrophilic phase PHI is advantageously between 5x107% and 10% by weight relative to the total weight of the hydrophilic phase PHI, preferably between 5x104 and 5% by weight.

[0070] The mass ratio between the monomer(s) A and the water-soluble control agent in the hydrophilic phase PHI is advantageously between 150:1 and 500,000:1, preferably between 100:1 and 300,000:1, more preferably between 50:1 and 150,000:1, more preferably between 10:1 and 100,000:1.

[0071] The lipophilic solvent of the PLI lipophilic phase can be a mineral oil, a vegetable oil, a synthetic oil or a mixture of these oils.

[0072] Examples of mineral oils are mineral oils containing saturated or unsaturated hydrocarbons of the aliphatic, naphthenic, paraffinic, isoparaffinic, cycloparaffinic or naphthyl type, examples include Exxsol™ D100, Exxsol™ D80, Isopar™ J, Isopar™ K, Isopar™ L, Isopar™ M, Isopar™ N marketed by ExxonMobil, white oils.

[0073] Examples of vegetable oils are squalene, an ester-type oil or triglycerides, such as coco caprylate / caprate, octyldodecyl myristate, ethoxylated vegetable oils, jojoba oil, macadamia oil.

[0074] Examples of synthetic oils are hydrogenated polydecene or hydrogenated polyisobutene, esters such as octyl stearate or butyl oleate.

[0075] The water-in-oil emulsifying agent is advantageously chosen from the following list: polyesters having a molecular weight between 1000 and 3000 g / mol, condensation products between poly(isobutenyl) succinic acid or its anhydride and polyethylene glycol, water-soluble sequence block polymers having a molecular weight between 2500 and 3500 g / mol, such as those sold under the names Hypermer®, extracts of sorbitan, such as sorbitan monooleate or polyoleates, sorbitan isostearate or sorbitan sesquioleate, polyethoxylated sorbitan esters, or even diethoxylated oleocetyl alcohol or tetraethoxylated lauryl acrylate, condensation products of fatty alcohols greater than ethylene, as a reaction product of oleic alcohol with 2 ethylene oxide units;Condensation products of alkylphenols and ethylene oxide, such as the reaction product of nonylphenol with 4 units of ethylene oxide. Ethoxylated fatty amines such as Witcamide® 511, betaine-based products, and ethoxylated amine are also good candidates as water-in-oil emulsifying agents.

[0076] The quantity of water-in-oil emulsifying agent in the lipophilic PLI phase is advantageously between 5 and 30% by weight relative to the total weight of the inverse emulsion, preferably between 10 and 25% by weight, more preferably between 15 and 20% by weight.

[0077] The mixing of the hydrophilic phase PHI and the lipophilic phase PLI is carried out under agitation, advantageously at a speed between 10 and 10,000 rpm (revolutions per minute), preferably between 100 and 1,000 rpm.

[0078] Agitation can be achieved by any system that provides homogeneous mixing; for example, a hand blender or a homogenizer. Preferably, the mixing is done with a hand blender.

[0079] Agitation is advantageously maintained during step b).

[0080] The weight ratio between the hydrophilic phase PHI and the lipophilic phase PLI in the inverse emulsion EMU is advantageously between 50 / 50 and 90 / 10, preferably between 60 / 40 and 85 / 15, more preferably between 70 / 30 and 80 / 20.

[0081] The quantity of monomer(s) in the EMU inverse emulsion is advantageously between 5 and 50% by weight relative to the total weight of the EMU inverse emulsion, preferably between 15 and 40% by weight.

[0082] Step bj

[0083] PI polymerization takes place in the presence of at least one initiator.

[0084] The initiator can be added to the hydrophilic phase PHI before or after the formation of the inverse emulsion EMU. Preferably, the initiator is added before the formation of the inverse emulsion EMI1.

[0085] In the case of a redox catalyst, it is possible to put the oxidant in PHI and pour the reducer or vice versa.

[0086] Advantageously used polymerization initiators can be chosen from compounds that dissociate into radicals under the polymerization conditions, for example: organic peroxides, hydroperoxides, hydrogen peroxide, persulfates, azo compounds, and redox catalysts. The use of water-soluble initiators is preferred. In some cases, it is advantageous to use mixtures of various polymerization initiators, for example, mixtures of redox salts and azo compounds.

[0087] Advantageously, the amount of initiator is between 5 and 1000 ppm relative to the total weight of monomer A of the hydrophilic phase PHI, preferably between 10 and 500 ppm, more preferably between 20 and 100 ppm.

[0088] Prior to polymerization, the atmosphere of the polymerization tank can be replaced by an inert gas such as nitrogen or argon.

[0089] Polymerization is advantageously carried out at a temperature between 1 and 70 °C, preferably between 5 and 60 °C, more preferably between 20 and 40 °C.

[0090] The polymerization time is advantageously between 60 minutes and 300 minutes, preferably between 90 minutes and 240 minutes.

[0091] Once polymerization has begun, the PP1 prepolymer starts to form.

[0092] The PP1 prepolymer obtained at the end of the PI polymerization has a molecular weight advantageously between 15,000 and 2,500,000 g / mol, preferably between 20,000 and 2,000,000 g / mol, more preferably between 25,000 and 1,500,000 g / mol. This is the average molecular weight by weight.

[0093] The hydrophilic phase PHI of the EMU inverse emulsion has a viscosity between 400 and 100,000 cps after the formation of the prepolymer PP1, preferably between 1,000 and 90,000 cps.

[0094] Step c)

[0095] Step c) can begin before the end of step b) of polymerization (but after the addition of the initiator has finished). In other words, it is not necessary to wait until all the monomers in the EMU emulsion have polymerized before adding the hydrophilic phase PH2. Preferably, step c) begins at the end of step b).

[0096] The hydrophilic phase PH2 has a composition distinct from the hydrophilic phase PHI.

[0097] By distinct composition, we mean a different monomer composition (ratio and / or nature of the monomers).

[0098] In a preferred mode, the hydrophilic phase PH2 is devoid of a control agent.

[0099] The combination of reversible addition-fragmentation chain transfer polymerization, from the beginning of step c) to the end of step b) and the use of different monomers A and B, makes it possible to obtain polymers with a block structure, which is not possible using a conventional inverse emulsion polymerization process.

[0100] The hydrophilic solvent SH2 of the hydrophilic phase PH2 may be different or identical to the hydrophilic solvent SH1 of the hydrophilic phase PHI.

[0101] The hydrophilic solvent SH2 is as defined for SH1. Preferably, it is the same hydrophilic solvent, advantageously it is water.

[0102] The quantity of monomer B in the hydrophilic phase PH2 is advantageously between 10 and 40% by weight relative to the total weight of the hydrophilic phase PH2, preferably between 15 and 35% by weight, more preferably between 20 and 30% by weight.

[0103] The amount of monomer B in the hydrophilic phase PH2 is advantageously between 0.1 and 99.9 mol% relative to the total amount of monomer of the water-soluble block polymer, preferably between 1 and 99 mol%, more preferably between 5 and 95 mol%, more preferably between 10 and 90 mol%, more preferably between 15 and 80 mol%, more preferably between 20 and 50 mol%.

[0104] The incorporation of the hydrophilic phase PH2 into the inverse emulsion EMI1 can be carried out continuously or discontinuously and / or in one step or several steps. Preferably, the addition is carried out in one step.

[0105] In a particular mode, the hydrophilic phase PH2 comprises at least one water-in-oil emulsifying agent, advantageously chosen from the list described above.

[0106] In a particular mode, it is possible in addition to the hydrophilic phase PH2 to incorporate a lipophilic phase PL2 in order to adjust the weight ratio of phase between the sum of the hydrophilic phases (PHI + PH2) and the sum of the lipophilic phases (PLI + PL2) of the reverse emulsion.

[0107] In the EMI2 reverse emulsion, the weight ratio between (hydrophilic phase PHI + hydrophilic phase PH2) and (lipophilic phase PLI + optionally lipophilic phase PL2) is advantageously between 50 / 50 and 90 / 10, preferably between 60 / 40 and 85 / 15, more preferably between 70 / 30 and 80 / 20.

[0108] The polymerization initiator P2 can be added directly into the hydrophilic phase PH2 or poured all at once into the formed PEMI2.

[0109] The mixing of the hydrophilic phase PH2 and the inverse emulsion EMI1 is carried out under agitation, advantageously at a speed between 50 and 1,000 rpm (rotations per minute), preferably between 100 and 500 rpm.

[0110] The duration of mixing the hydrophilic phase PH2 and the inverse emulsion EMU is advantageously between 30 minutes and 480 minutes, preferably between 40 minutes and 240 minutes, more preferably between 60 minutes and 120 minutes.

[0111] Agitation can be achieved by any system that provides homogeneous mixing; examples include a hand blender, a homogenizer, a mixing arm, and an agitation ink. Preferably, the mixing is carried out with an agitation ink.

[0112] Step d)

[0113] P2 polymerization takes place in the presence of at least one initiator.

[0114] The initiator can be added to the hydrophilic phase PH2 before or after the formation of the reverse emulsion EMI2. Preferably, the initiator is added before the formation of the reverse emulsion EMI2.

[0115] In the case of a redox catalyst, it is possible to put the oxidant in PH2 and pour the reducer or vice versa.

[0116] The initiator is advantageously chosen from among the initiators described above. Preferably, it is the same initiator as that used to initiate the polymerization in step b).

[0117] Advantageously, the amount of initiator present in the hydrophilic phase PH2 is between 5 and 1000 ppm relative to the total weight of active material (PP1 + monomer B) used for polymerization P2, preferably between 10 and 500 ppm, more preferably between 20 and 100 ppm.

[0118] Polymerization is advantageously carried out at a temperature between 5 and 70 °C, preferably between 10 and 50 °C, more preferably between 20 and 40 °C.

[0119] The polymerization time is advantageously between 60 minutes and 300 minutes, preferably between 90 minutes and 240 minutes.

[0120] Once the addition of the hydrophilic phase PH2 has started, the water-soluble block polymer is formed.

[0121] In a preferred mode, the P2 polymerization takes place in continuity with the PI polymerization, in other words the conditions applying to the P2 polymerization are the same as the conditions of the PI polymerization.

[0122] Polymerization is considered complete when a conversion rate of at least 70 mol% of the monomers (A+B) is achieved relative to the total amount of monomers present in the reaction medium, preferably at least 75 mol%, more preferably at least 80 mol%, even more preferably at least 85 mol%, even more preferably at least 90 mol%, and even more preferably at least 95 mol%. A person skilled in the art will be able to determine the conversion rate of the monomers, which remains a common practice and is part of their general knowledge.

[0123] The amount of water-soluble block polymer in the EMI2 inverse emulsion is advantageously between 5 and 50% by weight relative to the total weight of the EMI2 inverse emulsion, preferably between 15 and 40% by weight.

[0124] Specific and optional embodiment(s)

[0125] The process of the invention is not limited to the steps described above and may to understand others.

[0126] The process of the invention may include the addition of at least one oil-in-water emulsifying agent.

[0127] The addition of at least one oil-in-water emulsifying agent is generally done at the end of step d).

[0128] The oil-in-water emulsifying agent(s) are advantageously chosen from ethoxylated nonylphenols, preferably having 4 to 10 ethoxylations (i.e., preferably exhibiting a degree of ethoxylation ranging from 4 to 10); ethoxylated and / or propoxylated alcohols, preferably having an ethoxylation and / or propoxylation comprising 12 to 25 carbon atoms; ethoxylated tridecyl alcohols; ethoxylated and / or propoxylated fatty alcohols; ethoxylated sorbitan esters (advantageously having 20 molar equivalents of ethylene oxide); polyethoxylated sorbitan laurate (advantageously having 20 molar equivalents of ethylene oxide); polyethoxylated castor oil (advantageously having 40 molar equivalents of ethylene oxide); decaethoxylated oleodecyl alcohol; heptaoxyethylated lauric alcohol; polyethoxylated sorbitan monostearate (advantageously having 20 molar equivalents of ethylene oxide);alkyl phenol polyethoxylated (advantageously having 10 molar equivalents of ethylene oxide) cetyl ether; ethylene oxide alkyl aryl ether; N-cetyl-N-ethyl morpholinium ethosulfate; sodium lauryl sulfate; condensation products of fatty alcohols; with ethylene oxide (advantageously having 10 molar equivalents of ethylene oxide); condensation products of alkylphenols and ethylene oxide (advantageously having 12 molar equivalents of ethylene oxide); condensation products of fatty amines with 5 or more molar equivalents of ethylene oxide (advantageously 5 to 50 equivalents); ethoxylated tristyrylphenol; condensates of ethylene oxide with polyhydric alcohols partially esterified with fatty chains and their anhydrous forms; amine oxides advantageously having alkyl polyglucosides; glucamide; phosphate esters; alkylbenzenesulfonic acids and their salts; and surfactant block polymers and their mixtures. The alkyl groups of these oil-in-water emulsifying agents refer to linear or branched groups and advantageously have 1 to 20 carbon atoms, more advantageously 3 to 15 carbon atoms.Furthermore, the aryls of these oil-in-water emulsifying agents advantageously comprise 6 to 20 carbon atoms, more advantageously 6 to 12 carbon atoms.

[0129] Generally, the EMI2 inverse emulsion comprises between 0.01 and 10% by weight of oil-in-water emulsifying agent relative to the total mass of the inverse emulsion.

[0130] The process of the invention can be carried out in batch, semi-batch or continuous mode. It is advantageously carried out in batch mode.

[0131] In a particular embodiment, steps b) and d) are carried out at a pressure lower than atmospheric pressure, preferably at a pressure between 20 and 800 mbar, more preferably between 30 and 500 mbar, more preferably between 40 and 400 mbar.

[0132] In a particular embodiment, the process of the invention comprises, following polymerization P1 and / or polymerization P2, a step for removing residual monomers. The removal of residual monomers can be achieved, for example, by adding an excess of initiator.

[0133] The invention is not limited to the addition of a second hydrophilic phase PH2; it may include the addition of n hydrophilic phases (with n an integer greater than or equal to 2, n>2). In this case, the monomers of the hydrophilic phase PHn react with the prepolymer PPn-1, and it is then possible to obtain so-called multiblock polymers. The monomers present in these n hydrophilic phases may be identical or different in order to obtain multiblock polymers composed of different blocks (WXYZ) or multiblock polymers having an alternating structure (XYXY).

[0134] It is possible to add as many hydrophilic phases as desired, provided that the molecular weight of the prepolymer PP1 is between 10,000 g / mol and 3,000,000 g / mol, preferably between 15,000 g / mol and 2,500,000 g / mol, more preferably between 20,000 g / mol and 2,000,000 g / mol, and more preferably between 25,000 g / mol and 1,500,000 g / mol, than the molecular weight of the prepolymer PPn-1 obtained before the addition of the last hydrophilic phase PHn has a molecular weight less than 3,000,000 g / mol, preferably less than 2,500,000 g / mol, more preferably less than 2,000,000 g / mol, and even more preferably less than 1,500,000 g / mol, and that the viscosity of the hydrophilic phase PHI of the inverse emulsion EMU is between 400 and 100,000 cps after the formation of the prepolymer PP1, preferably between 1,000 and 90,000 cps and that the viscosity of the hydrophilic phase PH(nl) is less than 100,000 cps, preferably less than 90,000 cps.

[0135] Similarly, it is possible to add further lipophilic phases PLq (with q an integer greater than or equal to 1, n>l) in order to adjust the phase weight ratio between the sum of the hydrophilic phases (PHI + PH2 + PHn) and the sum of the lipophilic phases (PLI + PLq) of the reverse emulsion.

[0136] In a particular embodiment, the process of the invention includes an optional step e) of concentrating the inverse emulsion EMI2, advantageously by distillation, to form an inverse emulsion EMI2'. This concentration step consists of removing at least a portion of the hydrophilic phase and / or the lipophilic phase of the emulsion EMI2.

[0137] In the case of the addition of n hydrophilic phases and / or q lipophilic phases, the inverse emulsion EMIn is advantageously distilled to form the inverse emulsion EMIn' (with n an integer greater than or equal to 3, n> 3).

[0138] Distillation can be continuous or batch, with azeotropic entrainment. Preferably, distillation is continuous and a light oil (boiling point below 200 °C) is advantageously used as a lipophilic solvent to facilitate the entrainment of water.

[0139] The EMI2' inverse emulsion advantageously comprises between 20 and 80% by weight of water-soluble block polymer relative to the total weight of the EMI2' inverse emulsion, preferably between 30 and 70% by weight, more preferably between 35 and 60% by weight. Composition of the water-soluble block polymer

[0140] The radical polymerization preparation process according to the invention can be applied for the preparation of all types of water-soluble block polymers. Monomers A and B are advantageously chosen from monomers comprising at least one ethylenic function selected from non-ionic hydrophilic monomers, anionic hydrophilic monomers, cationic hydrophilic monomers, zwitterionic hydrophilic monomers, hydrophobic monomers, and mixtures thereof.

[0141] The invention is applicable to any monomeric composition of the water-soluble block polymer. Thus, the invention cannot be limited to a specific and preferred monomeric composition.

[0142] Monomers A and B may be identical or different. Preferably they are different.

[0143] When monomers A and B are identical, a water-soluble homopolymer is obtained.

[0144] When monomers A and B are different, a water-soluble block copolymer is obtained.

[0145] Advantageously, the hydrophilic non-ionic monomer(s) that may be used in the context of the invention are selected, in particular, from acrylamide, methacrylamide, N-alkylacrylamides, N-alkylmethacrylamides, N,N-dialkyl 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-methylol(meth)acrylamide, N-vinyl caprolactam, N-vinylformamide (NVF), N-vinyl acetamide, N-vinyl imidazole, N-vinyl succinimide, acryloyl morpholine (ACMO), the glycidyl methacrylate, vinyl acetate, glyceryl methacrylate, diacetone acrylamide, methacrylic anhydride, acrylonitrile, maleic anhydride, itaconic anhydride, itaconamide, hydroxyalkyl (meth)acrylates, thioalkyl (meth)acrylates, isoprenol and its alkoxylated derivatives,Hydroxyethyl(meth)acrylates and their alkoxylated derivatives, hydroxypropyl(meth)acrylate and its alkoxylated derivatives, and mixtures thereof. Among these nonionic monomers, the alkyl groups are advantageously in the C1-C5 position, more advantageously in the C1-C3 position. Preferably, the hydrophilic nonionic monomer is acrylamide.

[0146] Advantageously, the hydrophilic anionic monomer(s) that may be used in the context of the invention may be selected from a wide range. These monomers may have a vinyl functional group, in particular acrylic, maleic, fumaric, itaconic, or allylic. They may also contain a carboxylate, phosphonate, phosphate, sulfonate, sulfate, or other anionically charged group.Preferred monomers belonging to this class are, for example, acrylic acid; methacrylic acid; dimethylacrylic acid; acryloyl chloride; crotonic acid; maleic acid; fumaric acid; 3-acrylamido 3-methylbutanoic acid; strong acid-type monomers having, for example, a sulfonic acid or phosphonic acid function such as vinylsulfonic acid, vinylphosphonic acid, allylsulfonic acid, methallylsulfonic acid, 2-methylidenepropane-1,3-disulfonic acid, 2-sulfoethyl methacrylate, sulfopropyl methacrylate, sulfopropyl acrylate, acid. allylphosphonic acid, ethylene glycol methacrylate phosphate, styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid (ATBS), 2-acrylamido-2-methylpropane disulfonic acid, 3-allyloxy-2-hydroxypropane sulfonic acid, diethylallylphosphonate, carboxyethyl acrylate; water-soluble salts of these monomers such as their alkali metal, alkaline earth metal, or ammonium salts; and mixtures thereof. Preferably, the anionic hydrophilic monomer is acrylic acid.

[0147] In a particular embodiment of the invention, the anionic monomer(s) may be salified. It may also be a mixture of acidic and salified forms, for example a mixture of acrylic acid and acrylate.

[0148] By salification, we mean the substitution of a proton of at least one acidic functional group of the type -Ra(=O)-OH (where Ra represents P, S, or C) of the anionic monomer by a metal or organic cation to form a salt of the type -R(=O)-OX (where X is a metal or organic cation). In other words, the unsalified form corresponds to the acidic form of the monomer, for example, Rb-C(=O)-OH in the case of the carboxylic acid functional group, while the salified form of the monomer corresponds to the form Rb-C(=O)-OX+, where X+ corresponds to a metal or organic cation. The salification of the acidic functional groups may be partial or complete.

[0149] The metal cation is advantageously an alkali metal salt (Li, Na, K...) or an alkaline earth metal salt (Ca, Mg...), and the organic cation is advantageously the ammonium ion or a tertiary ammonium compound. Sodium salts are preferred.

[0150] Salification can take place before or after polymerization, preferably before.

[0151] In a particular mode, the polymer advantageously comprises between 1 and 100 mol% of water-soluble anionic monomer(s) in salified form, preferably between 50 and 100 mol%.

[0152] Advantageously, the cationic hydrophilic monomer(s) that can be used within the scope of the invention are chosen, in particular, from vinyl-type monomers, especially acrylamide, acrylic, allylic, or maleic monomers having a protonable amine or ammonium function, advantageously a quaternary ammonium. Examples include, in particular and without limitation, diallyldialkyl ammonium salts such as dimethyldiallylammonium chloride (DADMAC); acidified or quaternized dialkyl-aminoalkyl(meth)acrylamides, such as (3-methacrylamidopropyl)trimethylammonium chloride (MAPTAC) or (3-acrylamidopropyl)trimethylammonium chloride (APTAC); and acidified or quaternized dialkyl-aminoalkyl acrylate salts such as quaternized or salified dimethylaminoethyl acrylate (ADAME). acidified or quantified methacrylate salts dialkyl aminoalkyl compounds such as quaternized or saltized dimethylaminoethyl methacrylate (MADAME); acidified or quaternized salts of N,N-dimethylallylamine; acidified or quaternized salts of diallylmethylamine; acidified or quaternized salts of diallylamine; vinylamine obtained by the (basic or acidic) hydrolysis of an amide group -N(R2)-CO-R' with R1 and R2 being, independently, a hydrogen atom or an alkyl chain of 1 to 6 carbons, for example, vinylamine from the hydrolysis of N-vinylformamide; vinylamine obtained by Hofmann degradation; and mixtures thereof. Advantageously, the alkyl groups are in the C1-C7 configuration, preferably C1-C3, and may be linear, cyclic, saturated, or unsaturated chains. Preferably, the cationic hydrophilic monomer is quatemized or salified dimethylaminoethyl acrylate (ADAME).

[0153] A person skilled in the art will know how to prepare the quaternized monomers, for example, using a quaternizing agent of the type RX, where R is an alkyl group and X is a halogen or a sulfate. The quaternizing agent may be selected from dialkyl sulfates comprising from 1 to 6 carbon atoms or alkyl halides comprising from 1 to 6 carbon atoms. Preferably, the quaternizing agent is selected from methyl chloride, benzyl chloride, dimethyl sulfate, or diethyl sulfate. Furthermore, the present invention also covers DADMAC, APTAC, and MAPTAC type monomers in which the counterion is a sulfate, a fluoride, a bromide, or an iodide instead of a chloride.

[0154] By “quaternizing agent” is meant a molecule capable of alkylating a tertiary amine.

[0155] Advantageously, the hydrophilic zwitterionic monomer(s) that can be used in the context of the invention are chosen, in particular, from derivatives of a vinyl type motif (advantageously acrylamide, acrylic, allyl or maleic), this monomer having a quaternary amine or ammonium function and an acid function of the carboxylic (or carboxylate), sulfonic (or sulfonate) or phosphoric (or phosphate) type.

[0156] Preferably, this monomer comprises a quaternary amine or ammonium function and an acid function of the carboxylic (or carboxylate), sulfonic (or sulfonate) type or phosphoric (or phosphate).

[0157] In particular, and without limitation, examples include dimethylaminoethyl acrylate derivatives such as 2-((2-9(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, and dimethylaminoethyl methacrylate derivatives 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, propylacrylamide dimethylamino 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-(acryloyl) oxy) propyl] (dimethylammonio) acetate, dimethylamino propyl methylacrylamide, or derivatives such as 2-((3-methacrylamidopropyl) dimethylammonio) ethane-1-sulfonate, 3-(dimethylammonio)propane-1-sulfonate, 4-((3-methacrylamidopropyl)dimethylammonio)butane-1-sulfonate and propyl[3-(methacryloyloxy)](dimethylammonio)acetate and mixtures thereof.

[0158] Other hydrophilic zwitterionic monomers may be used, including those described by the Applicant in document WO2021 / 123599.

[0159] In a particular embodiment, the polymer may comprise at least one LCST group.

[0160] According to the general knowledge of those skilled in the art, a LCST group corresponds to a group whose solubility in water, for a given concentration, changes above a certain temperature and depending on the salinity. It is a group exhibiting a heating transition temperature that defines its lack of affinity for the solvent medium. This lack of affinity for the solvent results in opacification or loss of transparency, which can be due to precipitation, aggregation, gelation, or viscosification of the medium. The minimum transition temperature is called the "LCST" (Lower Critical Solution Temperature). For each concentration of an LCST group, a heating transition temperature is observed. This temperature is higher than the LCST, which is the minimum point on the curve.Below this temperature, the polymer is soluble in water; above this temperature, the polymer loses its solubility in water.

[0161] In a particular embodiment, the polymer may comprise at least one UCST group.

[0162] According to the general knowledge of a person skilled in the art, a UCST group corresponds to a group whose solubility in water, for a given concentration, is modified below a certain temperature and as a function of salinity. It is a group exhibiting a cooling transition temperature that defines its lack of affinity for the solvent medium. This lack of affinity for the solvent results in opacification or loss of transparency, which may be due to precipitation, aggregation, gelation, or viscosification of the medium. The maximum transition temperature is called " UCST (Upper Critical Solution Temperature). For each group concentration at UCST, a cooling transition temperature is observed. This temperature is lower than the UCST, which is the maximum point on the curve. Above this temperature, the polymer is soluble in water; below this temperature, the polymer loses its solubility in water.

[0163] Advantageously, the monomer(s) having a hydrophobic character that can be used within the framework of the invention can be chosen, in particular, from (meth)acrylic acid esters having a (i) C4-C30 alkyl chain, or (ii) arylalkyl (C4-C30 alkyl, C4-C30 aryl), or (iii) propoxylated, or (iv) ethoxylated, or (v) ethoxylated and propoxylated; alkyl aryl sulfonates (C4-C30 alkyl, C4-C30 aryl); Mono- or di-substituted amides of (meth)acrylamide having a (i) C4-C30 alkyl chain, or (ii) an arylalkyl (C4-C30 alkyl, C4-C30 aryl), or (iii) a propoxylated, or (iv) an ethoxylated, or (v) an ethoxylated and propoxylated chain; anionic or cationic monomeric derivatives of (meth)acrylamide or (meth)acrylic acid bearing a hydrophobic chain; and mixtures thereof. The hydrophobic monomers may include halogen atoms, for example, chlorine.

[0164] Among these hydrophobic monomers: - Alkyl groups are preferably in C4-C2O, more preferably in C4-C8. Alkyls in C6-C2O are preferably linear alkyls, while alkyls in C4-C5 are preferably branched. - arylalkyl groups are preferably in C7-C25, more preferably in C7-C 15, - the ethoxylated chains advantageously comprise between 200 -CH2-CH2-O- groups, preferably between 6 and 100, more preferably between 10 and 40, - the propoxylated chains advantageously comprise between 1 and 50 -CH2-CH2-CH2-O- groups, more preferably between 1 and 20.

[0165] Preferred hydrophobic monomers belonging to these classes are, for example: - n-hexyl (meth)acrylate, n-octyl (meth)acrylate, octyl (meth)acrylamide, lauryl (meth)acrylate, lauryl (meth)acrylamide, myristyle (meth)acrylate, myristyle (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, N-tert-Butyl(meth)acrylamide, vinylpyridine, 2-ethylhexyl acrylate, hemi-esters of acid C4-C22 itaconic, acidified or quantified salts of dialkyl aminoalkyl (meth)acrylate in C4-C 22, acidified or quaternized salts of C4-C22 dialkyl-aminoalkyl(meth)acrylamides, acrylamidoundecanoic acid, and mixtures thereof, - cationic allyl derivatives of formula (VII) or (VIII):

[0166] [Chem.7] (VII) (VIII)

[0167] in which: R: independently an alkyl chain containing 1 to 4 carbons; Ri: an alkyl or arylalkyl chain comprising 8 to 30 carbons; X: a halide chosen from the group consisting of bromides, chlorides, iodides, fluorides and any negatively charged counter-ion; and, preferably, hydrophobic cationic derivatives of the (meth)acryloyl type corresponding to formula (IX):

[0168] [Chem. 8] (IX)

[0169] in which: - A represents O or N-R5 (preferably A represents N-R5), - R2, R3, R4, R5, R6, R?: independently a hydrogen atom or an alkyl chain containing 1 to 4 carbons, - E: an alkyl chain comprising 1 to 20 carbons, - R8: an alkyl or arylalkyl chain comprising 8 to 30 carbons, - X: a halide chosen from the group consisting of bromides, chlorides, iodides, fluorides, and any negatively charged counter-ion.

[0170] The water-soluble block polymer advantageously comprises less than 3 mol% of hydrophobic monomers.

[0171] When the water-soluble block polymer comprises at least one hydrophobic monomer, its quantity is adjusted so that the polymer remains soluble in water.

[0172] The hydrophobic monomer(s) can be added in step a) or c), preferably in step c).

[0173] The quantities of the different monomer(s) will be adjusted by a person skilled in the art so as not to exceed 100% molar during the preparation of the water-soluble block polymer according to the invention.

[0174] The water-soluble block polymer can have a linear, branched, cross-linked, star-shaped, or comb-shaped structure. This structure can be obtained, according to the general knowledge of those skilled in the art, for example by selecting the initiator, the transfer agent, the water-soluble control agent, the incorporation of structural monomers, or the concentration.

[0175] The water-soluble block polymer can further be structured by a branching agent. Structured refers to a non-linear polymer that has side chains.

[0176] The branching agent is advantageously chosen from: - structural agents, which can be chosen from the group comprising monomers with polyethylenic unsaturation (having at least two unsaturated functions), such as vinyl functions, particularly allylic or acrylic, and examples include methylene bisacrylamide (MBA), triallyamine, or tetraallylammonium chloride or 1,2-dihydroxyethylene bis-(N-acrylamide), - monomers having at least two epoxy functional groups, - monomers having at least one unsaturated function and one epoxy function, - Macroinitiators such as polyperoxides, polyazo compounds, and polytransfer agents such as polymer-capturing polymers and polyols, - Functionalized polysaccharides, - water-soluble metal complexes composed of: * of a metal with a valence greater than 3 such as, by way of example and without limitation, aluminium, boron, zirconium or titanium, and * of a ligand bearing a hydroxyl function.

[0177] The branching agent can be added in step a) or c).

[0178] When the water-soluble block polymer includes a branching agent, it remains soluble in water. A person skilled in the art will know how to adjust the amount of branching agent, and possibly the amount of transfer agent, to achieve this result.

[0179] In a particular mode, the water-soluble block polymer does not include a branching agent.

[0180] In a particular mode, the water-soluble block polymer may include a transfer agent.

[0181] The transfer agent is advantageously chosen from methanol; isopropyl alcohol; sodium hypophosphite; calcium hypophosphite; magnesium hypophosphite; potassium hypophosphite; ammonium hypophosphite; formic acid; sodium formate; calcium formate; magnesium formate; potassium formate; ammonium formate; 2-mercaptoethanol; 3-mercaptopropanol; dithiopropylene glycol; thioglycerol; thioglycolic acid; thiohydracrylic acid; thiolactic acid; thiomalic acid; cysteine; aminoethanethiol; thioglycolates; allyl phosphites; allyl mercaptans, such as n-dodecyl mercaptan; sodium methallysulfonate; calcium methallysulfonate; magnesium methallysulfonate; potassium methallysulfonate; ammonium methallysulfonate;Alkyl phosphites such as trialkyl (C12-C15) phosphites, dioleyl hydrogen phosphites, dibutyl phosphite; dialkyldithiophosphates such as dioctyl phosphonate; tertiary nonyl mercaptan; 2-ethylhexyl thioglycolate; n-octyl mercaptan; n-dodecyl mercaptan; tertio-dodecyl mercaptan; iso-octylthioglycolate; 2-ethylhexyl thioglycolate; 2-ethylhexyl mercaptoacetate; polythiols; and mixtures thereof. Preferably, this is sodium hypophosphite or sodium formate.

[0182] The transfer agent can be added in step a) or c).

[0183] In a particular mode, the water-soluble block polymer does not include a transfer agent.

[0184] The water-soluble block polymer according to the invention can have a molecular weight covering all applications in which high molecular weight polymers can be used. Thus, the water-soluble block polymer advantageously has a molecular weight of at least 100,000 g / mol, preferably at least 1,000,000 g / mol, more preferably at least 1,500,000 g / mol, more preferably at least 2,000,000 g / mol, more preferably at least 3,000,000 g / mol, more preferably at least 5,000,000 g / mol, more preferably at least 7,000,000 g / mol, and more preferably at least 10,000,000 g / mol. This is the average molecular weight by weight. Advantageously, the molecular weight of the water-soluble block polymer is less than 30,000,000 g / mol, preferably less than 20,000,000 g / mol, and more preferably less than 15,000,000 g / mol.

[0185] The polydispersity index (Ip) of the polymer obtained according to the invention is advantageously less than or equal to 5 (<5), preferably less than or equal to 4 (<4), preferably less than or equal to 3 (<3), more preferably less than or equal to 2 (<2), and even more preferably less than or equal to 1.5 (<1.5). It is advantageously between 1 and 2. The polydispersity index is determined according to the following formula: Ip = Mw / Mn Mw is the average molecular weight by weight; Mn is the average molecular weight by number.

[0186] The present invention also relates to a water-soluble block polymer obtained according to the process of the invention.

[0187] The present invention also relates to the use of this water-soluble block polymer in: hydrocarbon (oil or gas) recovery; well drilling; well cementing; hydrocarbon (oil or gas) well stimulation, for example hydraulic fracturing, conformance, diversion; open, closed or semi-closed water treatment; fermentation must treatment; sludge treatment; construction; paper or cardboard manufacturing; the battery field; wood processing; hydraulic composition processing (concrete, cement, mortar and aggregates); the mining industry; cosmetic formulation; detergent formulation; textile manufacturing; geothermal energy; sanitary diaper manufacturing; or agriculture.

[0188] Finally, the present invention also relates to the use of this water-soluble block polymer as a flocculant, coagulant, binding agent, fixing agent, viscosity reducing agent, thickening agent, absorbing agent, friction reducing agent, draining agent, charge retention agent, dehydrating agent, conditioning agent, stabilizing agent, film-forming agent, sizing agent, superplasticizing agent, clay inhibitor or dispersant.

[0189] The invention and its advantages will become clearer from the following figures and examples, which are given to illustrate the invention and not to limit it. Description of figures

[0190] [Fig.1] Fig.1 illustrates the measurement of the molecular weight of example PP1-CE3 (Counterexample) by size exclusion chromatography (SEC).

[0191] [Fig.2] The [Fig.2] illustrates the measurement of the molecular weight of example PP1-6 (Invention) by size exclusion chromatography (SEC). Examples

[0192] List of abbreviations: AM: Acrylamide; AA: Acrylic acid; ADC: [2-(Acryloyloxy)ethyl]trimethylammonium chloride; ATBS: 2-Acrylamido-2-methylpropane sulfonic acid. Polymer characterization

[0193] Characterization of average molar masses by number (Mn), by weight (Mw) and polydispersity index

[0194] The polymers were analyzed by size exclusion chromatography (SEC) to determine the average molar masses (Mn, Mw). The analytical conditions were as follows: - 1 pre-column “Shodex” referenced SB807-G; - 2 "Shodex OHpak" columns mounted in series, referenced SB-807 HQ / SB-805 HQ); - The columns are coupled with a refractive index detector referenced "Optilab T-rEX" and "Dawn Heleos II" 18 angles marketed by the company Wyatt Technology. Characterization of apparent viscosities

[0195] The apparent viscosities of the hydrophilic phase of the EMU inverse emulsion are measured according to the following procedure: - precipitation in acetone of the prepoplymer PP1, under agitation (1000 rpm (rotations per minute)); - recovery by filtration of the PP1 prepolymer in solid form; - drying of the PP1 prepolymer in solid form in an oven at 30 °C for 24 h; - re-dissolution of the dried PP1 prepolymer in a 7% by weight sodium chloride solution; - measurement of apparent viscosity using a Brookfield LVT or LVD viscometer at a temperature between 23 and 25 °C.

[0196] Characterization of particle sizes and particle size distributions of inverse polymer emulsions

[0197] The polymers were analyzed by laser diffraction. The instrument used was the MASTERSIZER MS3000, marketed by Malvem. This instrument measures particle sizes from 0.5 to 2000 µm. It also measures the particle size distribution. This instrument has an organic liquid channel for the analysis of aqueous polymer particles emulsified in oil.

[0198] The device is equipped with three main elements which enable the system to provide accurate particle size data consistently and reliably: - an optical bench: equipped with a laser beam (1 single optical measurement path) - a sample dispersion unit - Mastersizer 3000 software which controls the system during measurement and analyzes diffusion data.

[0199] Example 1: Synthesis of a water-soluble control agent Xa

[0200] In a synthesis reactor, the following are introduced at room temperature: - 4.53 g of o-ethyl-S-(l-methoxycarbonyl)ethyl dithiocarbonate; - 22.66 g of acrylamide; - 27.19 g of deionized water; - 45.31 g of acetic acid; - 0.32 g of azo initiator (“VA 044”).

[0201] The reaction mixture is degassed and then heated to 60 °C. The reaction is stirred for 3 h.

[0202] The control agents Xb to Xh are prepared according to the protocol described in the example 1. The nature of the groups composing these control agents Xa to Xh is presented in Table 1 below:

[0203] [Tables 1] Water-soluble control agent Ri ZC(S) SQ R2 Ri Ri ZQ Composition Mil (g / moi) Xa c>h5 CH(CH3)-COOCH3 O AM 700 Xh c2h; CH(CH3)-COOCH3 O AM 1400 Xc (ML CH(CH3)-COOCH3 O - - HOOC-C2H5 CHtCH3LCOOH s - - Table 1#: Control Agents Xa to Xh

[0204] Example 2: Preparation of EMU inverse emulsions (step a)) and PP1-1 to PP1-23 prepolymers (step b))

[0205] Example 2a: Preparation of an EMI emulsion and a PPl-l prepolymer according to the invention

[0206] Preparation of the hydrophilic phase PHI: In a reactor equipped with an agitation system, the following are mixed at room temperature: - 276.7 g of acrylamide (50% by weight in water); - 60.1 g of acrylic acid; - 170.3 g of deionized water; - 60.1 g of sodium hydroxide (50% by weight in water) - 50 ppm of tertiary butyl hydroperoxide; - 5,000 ppm of the water-soluble control agent Xc relative to the weight of the monomers.

[0207] Preparation of the lipophilic phase PLI: Water-in-oil emulsifiers (2.5% by weight relative to the weight of the inverse emulsion), and a mixture of alkanolamide and sorbitan mono oleate, are mixed in 250 g of "Exxsol D100" oil.

[0208] Emulsification (step a)) and polymerization (step b)): The hydrophilic phase PHI is mixed and emulsified in the lipophilic phase PLI. The resulting inverse emulsion EMI1-1 is then degassed for 60 minutes before polymerization Pl-1 is initiated at room temperature by pouring 8 mL of a 1 g / L aqueous sodium metabisulfite solution to form the prepolymer PP1-1.

[0209] Example 2b: Preparation of EMI1-2 to EMI1-23 reverse emulsions and PP1-2 to PP1-23 prepolymers

[0210] The reverse emulsions EMI1-2 to EMI1-23 and prepolymers PP1-2 to PP1-23 are prepared according to the experimental protocol described in Example 2a.

[0211] Counterexamples of emulsions and prepolymers are also prepared, without the addition of a control agent, by a protocol identical to that described in Example 2a.

[0212] The compositions and properties of EMI1-2 to EMI1-23 and PP1-2 to PP1-23 prepolymers are shown in Tables 2 and 3 below.

[0213] [Tables2] Inverse Emulsion Apparent Viscosity (cP, 30 rpm) Polydispersity of Polymer Particles in PP1 Inverse Emulsion EMU 1 1380 Monodisperse EMU 2 1210 Monodisperse EMU-3 1320 Monodisperse EM114 1750 Monodisperse EMU 5 1420 Monodisperse EMU-6 1380 Monodisperse EMU 7 1950 Monodisperse EMUS 5980 Monodisperse EMU-9 21200 Monodisperse EMU40 12400 Monodisperse EMU 11 9990 Monodisperse EMU 12220 Monodisperse EMU 13 102000 Monodisperse EMU 14 1350 Monodisperse EMU-15 1920 Monodisperse EMH16 1300 Monodisperse EMU 17 1,750 Monodisperse EMU 18 1,430 Monodisperse EMU 19 1,380 Monodisperse EMU 20 1,360 Monodisperse EMU 21 1,450 Monodisperse EMU 22 1,690 Monodisperse EMU 23 1,400 Monodisperse

[0214] Table 2 - Properties of EMI1-1 to EMI1-23 Reverse Emulsions

[0215] [Tables3] Prépolymer Composition (mol%) Control Agent Mn (g / mol) Polymer in PPI AM AA A DC ATBS PPI 1 70 30 X3 355 000 PP1-2 100 - - XI 347 900 PPI 3 50 30 20 X4 348 500 PP1-4 40 60 X5 1 150 000 PP1-5 10 90 - X7 415 000 PPI 6 - 50 50 - XI 373 250 PPI 7 20 10 50 20 X2 450 000 PP1 S s - 95 - X2 452 000 PPI 9 5 95 - - X6 561 000 PPI 10 - 100 - - X3 1 457 000 PP1 11 - - 100 - X5 167 450 PP1 12 70 30 - - 30 - - 300 PP1-21 •" 50 50 - - 350 900 PPI 22 40 - 60 - - 1 066 100 PPI 23 50 20 30 - - 347 200

[0216] Tableau 3 : Composition and properties of the polymers according to the invention and examples

[0217] Example 3: Preparation of EMI2 inverse emulsions and block hydrosoluble polymers

[0218] EMI2 emulsions are obtained by mixing under stirring at 200 rpm for 240 minutes and at room temperature: - EM1 comprising the PP1 prepolymer; - a hydrophilic PH2 phase comprising the monomers entering into the composition of the block water-soluble polymer and 50 ppm of tert-butyl hydroperoxide; - a lipophilic phase PL2, in order to adjust the quantities of final active materials and the hydrophilic / lipophilic phase ratios, comprising water-in-oil emulsifiers (2.5% by weight relative to the weight of the inverse emulsion), and a mixture of alkanolamide and sorbitan mono oleate, mixed with "Exxsol D100" oil.

[0219] EMI2 is then degassed for 60 minutes before polymerization is initiated by pouring 8 mL of an aqueous solution of 1 g / L sodium metabisulfite.

[0220] The particle size, particle size distributions, and number-average molar masses of the water-soluble block polymers of EMI2 are characterized. To characterize the molar masses, the polymers were precipitated in acetone.

[0221] The compositions of the different hydrophilic PH2 phases and the characteristics of the water-soluble block polymers obtained after polymerization are summarized in Table 4.

[0222] [Tables4] Reference Assay PP1 Composition (moi%) of PH2 Final Active Matter P2(%) Measured Mb of P2 Polymers (g / mol) Polydispersity of Polymer Particles in Reverse Femnlsion of P2 AM AA ADC ATBS El PP1-1 70 30 30 - 10 04 04 056 Monopopulation E2 PP1-2 100 - - - 21 1 687 000 Monopopulation E3 PP1-3 50 30 - 20 21 3 123 600 Monopopulation E4 PP1-4 40 - 60 - 21 4 876 000 PP Mono popula tion E5 - 01 - 193 612 000 Monopopulation E6 PP1 6 - 50 50 - 21 1 184 000 Monopopulation E7 PP1-7 20 10 50 20 21 2 150 000 Monopopulation ES PP 18 5 - 95 - 21 PP 807 - 95 95 - - 21 2 894 500 Monopopulation E10 PP1-10 - 100 - - 21 6 454 000 Monopopulation Eli PP1-11 - - 100 21 913 000 Monopopulation E-CE1 PP 1-12 70 32 20 - NM.- LP NM - LP E-CE2 PP1-13 70 30 - 21 NM - LP NM - LP E-CE3 PP1-14 70 30 - 21 NM - LP NM -LP E-CE4 PP1-15 70 30 - - 21 NM - LP NM - LP E-CE5 PP 1-16 100 - - 21 NM - LP NM - LP E-CE6 PP 1-17 70 30 - - 21 NM - LP NM-LP E-CE7 PP1-18 70 30 - 21 NM - LP NM - LP E-CE8 PPL19 60 40 21 NM - LP NM - LP E-CE9 PP 1-20 40 - 60 - 21 NM - LP NM-LP E-CE10 PP1-21 - 50 50 - 21 NM - LP NM - LP E-CE11 PP 1-22 40 - 60 21 NM - LP NM-LP E-CE12 PP 1-23 50 20 30 - 21 NM - LP NM - LP .

[0223] Table 4 - Composition of PH2 and characteristics of water-soluble block polymers (NM: Not measurable; LP: Large Polypopulation)

[0224] These results demonstrate that the presence of a control agent for the formation of a PP1 prepolymer having a well-defined molecular weight combined with an inverse emulsion viscosity is necessary to obtain high molecular weight block water-soluble polymers of the invention.

[0225] Figures 1 and 2 show the result of size exclusion chromatography for tests E1 and E-CE1. For [Fig. 1], a monodispersity of the molecular weights for PP1-12 and when used to form the water-soluble block polymer, a final polydisperse population is observed, corresponding to the formation of a multitude of droplets of different sizes comprising water-soluble block polymers with varying molecular weights, which corresponds to poor integration of PH2.

[0226] On the contrary for [Fig.2], we observe a monodispersity for PP1-1 and also for the water-soluble block polymer resulting from its polymerization, which corresponds to a good integration of PH2 and which allows us to obtain high molecular weight water-soluble block polymers with a monopopulation.

Claims

Demands

1. A process for preparing a water-soluble block polymer by radical polymerization, by reversible addition-fragmentation chain transfer in an inverse emulsion, comprising the following steps: a) Mixing a hydrophilic phase PHI and a lipophilic phase PLI under stirring to form an inverse emulsion EMU, the hydrophilic phase PHI comprising at least one hydrophilic solvent SH1, at least one monomer A and at least one water-soluble control agent of formula (I): [Chem.l] (I) in which - Z represents O, S or NR3; - Ri, R2, and R3, whether identical or different, represent: * a group (i), alkyl, acyl, alkenyl or alkynyl, possibly substituted, or * a carbon ring (ii), saturated or unsaturated, possibly substituted or aromatic, or * a heterocycle (iii), saturated or unsaturated, possibly substituted or aromatic, these groups and rings (i), (ii) and (iii) can be substituted by substituted aromatic groups or by alkoxycarbonyl or aryloxycarbonyl groups (-COOR), carboxy (-COOH), acyloxy (-O2CR), carbamoyl (-CON(R)2), cyano (-CN), alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl, phthalimido, maleimido, succinimido, amidino, guanidimo, hydroxy (-OH), amino (-N(R)2), halogen, allyl, epoxy, alkoxy (-OR), S-alkyl, S-aryl, groups exhibiting hydrophilic or ionic character such as alkali salts of carboxylic acids, alkali salts of sulfonic acid, polyalkylene oxide chains (POE, POP), cationic substituents (quaternary ammonium salts); - R representing an alkyl or aryl group in Ci-C20; - R3 can also represent a hydrogen atom; - Q is a linear or structured polymeric chain comprising n identical or different hydrophilic monomers comprising at least one ethylenic function; - n is an integer between 0 and 500, advantageously between 1 and 500, more advantageously between 1 and 100, Q being a single bond between the sulfur atom and the R2 group when n is equal to 0; the lipophilic phase PLI comprising at least one lipophilic solvent and at least one water-in-oil emulsifying agent; b) Polymerization PI, in the presence of at least one initiator, of at least monomer A of the inverse emulsion EMU to form a prepolymer PP1 having a molecular weight between 10,000 and 3,000,000 g / mol and having a viscosity between 400 and 100,000 cps; c) Addition and mixing, at EM1, of a hydrophilic phase PH2 comprising at least one hydrophilic solvent SH2 and at least one monomer B to form a reverse emulsion EMI2;the hydrophilic phase PH2 and the hydrophilic phase PHI having distinct compositions, d) Polymerization P2, in the presence of at least one initiator, of at least monomer B on the prepolymer PP1 in order to form a water-soluble block polymer.;

2. A process according to claim 1, characterized in that the hydrophilic phase PHI comprises an amount of monomer A of between 10 and 50%, by weight relative to the total weight of the hydrophilic phase PHI.

3. A process according to claim 1 or 2, characterized in that the hydrophilic phase PHI comprises an amount of water-soluble control agent of between 5x10 7% and 10%, by weight relative to the total weight of the hydrophilic phase PHI.

4. A process according to any one of claims 1 to 3, characterized in that the lipophilic PLI phase comprises an amount of water-in-oil emulsifying agent of between 5 and 30%, by weight relative to the total weight of the inverse emulsion.

5. A method according to any one of claims 1 to 4, characterized in that, in step c), the addition of the hydrophilic phase PH2 to the reverse emulsion EMI1 is done in one step.

6. A process according to any one of claims 1 to 5, characterized in that, in step c), the mixing of the hydrophilic phase PH2 and the inverse emulsion EMU is carried out under agitation at a speed between 50 and 1000 rpm.

7. A process according to any one of claims 1 to 6, characterized in that, in step c), the mixing time of the hydrophilic phase PH2 and the inverse emulsion EMU is between 30 minutes and 480 minutes.

8. A method according to any one of claims 1 to 7, characterized in that monomers A and B are selected from non-ionic hydrophilic monomers, anionic hydrophilic monomers, cationic hydrophilic monomers, zwitterionic hydrophilic monomers and hydrophobic monomers.

9. A method according to any one of claims 1 to 8, characterized in that monomers A and B are different.

10. Water-soluble block polymer obtained according to any one of claims 1 to Q

11. 1 d 7. Use of the water-soluble block polymer obtained according to any one of claims 1 to 9, in hydrocarbon recovery; well drilling; well cementing; hydrocarbon well stimulation; open, closed or semi-closed circuit water treatment; fermentation must treatment; sludge treatment; construction; paper or cardboard manufacturing; battery manufacturing; wood processing; hydraulic composition processing; mining; cosmetic formulation; detergent formulation; textile manufacturing; geothermal energy; sanitary diaper manufacturing; or agriculture.

12. Use of the water-soluble block polymer obtained according to any one of claims 1 to 9, as a flocculant, coagulant, binding agent, fixing agent, viscosity reducing agent, thickening agent, absorbent agent, friction reducing agent, draining agent, charge retaining agent, dehydrating agent, conditioning agent, stabilizing agent, film-forming agent, sizing agent, superplasticizing agent, clay inhibitor or dispersant.

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