Emulsion polymerization method for fluoromonomers

Abstract

The present invention relates to a method for polymerizing fluoromonomers in the presence of certain amphiphilic reversible addition-fragmentation chain transfer (RAFT) agents.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to European Patent Application No. 21306824.0, filed December 17, 2021, the entire contents of which are incorporated herein by reference for all purposes.

[0002] The present invention relates to a method for polymerizing fluoromonomers in the presence of certain amphiphilic reversible addition-fragmentation chain transfer (RAFT) agents. [Background technology]

[0003] Vinylidene fluoride polymers, including thermoplastic and elastomeric polymers, are known to be produced by radical polymerization techniques.

[0004] Over the past decade, various controlled / living polymerization (CLP) techniques have proven effective in generating block copolymers that self-assemble to achieve controlled morphology in systems by extending hydrophilic living chains with hydrophobic segments, triggering polymerization-induced self-assembly. Among the CLP techniques, reversible addition-fragmentation chain transfer (RAFT) and macromolecular design via reversible addition-fragmentation chain transfer (RAFT) / Xanthates(MADIX) polymerization have been widely studied. See, for example, PERRIER, S., et al. Macromolecular design via Reversible Addition-Fragmentation Chain Transfer(RAFT) / Xanthates(MADIX) polymerization. J.Polym.Sci.:Part A:Polym.Chem..2005,vol.43,p.5347-5393.

[0005] For the avoidance of doubt, the expression "RAFT agent", which is intended to mean "RAFT agent or MADIX agent", is used herein to refer to a class of compounds containing the functional group -X(=S)-S-, where X is phosphorus or carbon, preferably carbon. MADIX agents are more specifically characterized by the presence of a xanthate functional group, i.e. -OC(=S)-S-. RAFT agents can act as reversible chain transfer agents in free radical polymerization, thereby inducing reversible addition-fragmentation transfer reactions, resulting in an equilibrium between propagating radicals (i.e. growing polymer chains) and so-called dormant species (containing fragments of the chain transfer agent), the latter of which can become active again. The generally accepted mechanism of RAFT-controlled radical polymerization is shown in Scheme I.

[0006] US Patent No. 7,012,114 (RHODIA CHIMIE) discloses the free radical emulsion polymerization of at least one ethylenically unsaturated monomer in the presence of a free radical initiator with a polymer terminated with a group selected from dithioesters, thioether-thiones, dithiocarbamates, and xanthates. The polymer may have units derived from hydrophilic and hydrophobic monomers and may be a monoblock, diblock, or triblock polymer. The ethylenically unsaturated monomer is represented by the formula CX d X' d (=CV d -CV' d ) t ═CH2, where X d and X' d are the same or different and represent H, an alkyl group, or a halogen; V d and V' d are the same or different and are H, halogen or a group R, OR, OCOR, NHCOH, OH, NH2, NHR, N(R)2, (R)2N + O -, NHCOR, CO2H, CO2R, CN, CONH2, CONHR, or CONR2, where R is the same or different and is selected from the group consisting of alkyl, aryl, aralkyl, alkaryl, alkene, and organosilyl groups, optionally fully fluorinated and optionally substituted with one or more carboxyl, epoxy, hydroxyl, alkoxy, amino, halogen, or sulfone groups, and t is 0 or 1. No mention is made of the possibility of polymerizing vinylidene fluoride in the presence of said polymers bearing dithioester, thioetherthione, or dithiocarbamate functional groups.

[0007] WO 2006 / 037171 (University of Sydney) discloses a method for polymerizing certain monomers in the presence of a RAFT agent and certain particulate materials, the RAFT agent having the formula: [ka] wherein each A and B is independently -(A) m -(B)0- is the polymerized residue of an ethylenically unsaturated monomer such that - confers hydrophobicity and -(B)0- confers hydrophilicity. According to this document, a wide range of ethylenically unsaturated monomers can be polymerized according to this method, suitable monomers being those that can be polymerized by free radical processes, although vinylidene fluoride is not mentioned.

[0008] WO 2015 / 173193 A (SOLVAY SPECIALTY POLYMERS ITALY SpA) 19.11.2015 relates to a process for the emulsion polymerization of fluoromonomers under the control of RAFT / MADIX agents. Summary of the Invention

[0009] Therefore, a first object of the present invention is to provide a compound according to the formula (I) which is described in detail below: [ka] The present invention provides a method for producing a fluoropolymer latex in the presence of an amphiphilic polymeric RAFT agent [Reagent (R)] of the formula:

[0010] Applicants have surprisingly found that, by virtue of a self-assembled polymeric micellar structure in the form of an outer hydrophilic shell and an inner hydrophobic core, Reagent (R) functions as an effective amphiphilic particulate emulsifier for fluoromonomer polymerization, is effective in supporting the polymerization of fluoromonomers, particularly vinylidene fluoride (VDF), up to high solids contents, and stabilizes the resulting latex without the need for the addition of a surface agent. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] According to a first object of the present invention, there is provided a process for the emulsion polymerization of at least one fluoromonomer, comprising the steps of: a monomer mixture [mixture (M)] comprising at least one fluoromonomer and optionally at least one additional monomer, with a monomer mixture of formula (I): [ka] Amphiphilic polymeric RAFT agents [Reagents (R)] (In the formula, R a is an organic group optionally substituted with one or more hydrophilic groups; -[A] n - represents a sequence of repeating units -A- derived from at least one ethylenically unsaturated monomer having hydrophilicity [monomer (A)], and n represents an integer of 2 to 300, preferably 2 to 250, further 3 to 200, more preferably 3 to 150, and further preferably 3 to 120; -[B] m - represents a sequence of repeating units -B- derived from at least one ethylenically unsaturated monomer having hydrophobicity [monomer (B)], and m represents an integer of 2 to 300, preferably 2 to 250, further 3 to 200, more preferably 3 to 150, and further preferably 3 to 120; Z is optionally substituted alkoxy, optionally substituted aryloxy, optionally substituted heterocyclyl, optionally substituted alkylthio, optionally substituted arylalkylthio, dialkoxy- or diaryloxy-phosphinyl [-P(=O)(OR 4 )2], dialkyl- or diarylphosphinyl [-P(=O)R 4 2], R 4 is optionally substituted C1 to C 18 Alkyl, optionally substituted C2-C 18 is selected from the group consisting of alkenyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted aralkyl, optionally substituted alkaryl, optionally substituted acylamino, optionally substituted acylimino, optionally substituted amino, polymer chains formed by any mechanism; Z is optionally substituted alkyl, preferably optionally substituted C1-C 20 R may be further selected from the group consisting of alkyl, optionally substituted aryl, and optionally substituted arylalkyl; 4 and optional substituents for the Z group include epoxy, hydroxy, alkoxy, acyl, acyloxy, carboxy (and its salts), sulfonic acid (and its salts), alkoxy- or aryloxy-carbonyl, isocyanato, cyano, silyl, halo, and dialkylamino. and polymerizing in an aqueous medium comprising - Terminating the polymerization and recovering the latex of the fluoropolymer [polymer (F)]; A method is provided that includes:

[0012] Typically, Z is, but not limited to, -R 5 , -OR 5 , -SR5 (In the formula, R 5 is optionally substituted C1 to C 20 alkyl);-NR 5 R 6 (In the formula, R 5 is as defined, and R 6 is optionally substituted C1 to C 20 and alkyl, optionally substituted aryl; and [ka] (In the formula, e is an integer of 2 to 4.) is selected from the group consisting of:

[0013] Preferably, Z is -OR 5 , -SR 5 (In the formula, R 5 is optionally substituted C1 to C 20 alkyl);-NR 5 R 6 (In the formula, R 5 is as defined, and R 6 is optionally substituted C1 to C 20 and alkyl, optionally substituted aryl; and [ka] (In the formula, e is an integer of 2 to 4.) is selected from the group consisting of:

[0014] More preferably, Z is -SR 5 (In the formula, R 5 is optionally substituted C1 to C 20 alkyl);-NR 5 R 6 (In the formula, R 5 is as defined, and R 6 is optionally substituted C1 to C 20and alkyl, optionally substituted aryl; and [ka] (In the formula, e is an integer of 2 to 4.) is selected from the group consisting of:

[0015] Even more preferably, Z is -SCH2(C6H5), -S(CH2) u COH (wherein u is an integer from 2 to 11), -OC z H 2z+1 , -SC z H 2z+1 (wherein z is an integer of 1 to 12, preferably an integer of 2 to 12, for example, but not limited to, 2, 3, 4, 6, 8, 10, and 12), -SCH2CH2OH, -OCH2CF3, and -N(C6H5)(CH3), but is not limited thereto.

[0016] In formula (I), R a can be selected from C1-C6 alkyl, C1-C6 alkoxy, aryl, or heteroaryl, each of which is selected from -CO2H, -CO2R, -CN, -SO3H, -OSO3H, -SOR, -S2R, -OP(OH)2, -P(OH)2, -PO(OH)2, -OH, -OR, -(OCH2-CHR 0 ) w -OH, -(OCH2-CHR 0 ) w -OR, -CONH2, CONHR 1 ,CONR 1 R 2 , -NR 1 R 2 , -NR 1 R 2 R 3 R is selected from C1-C6 alkyl; R 0 is selected from hydrogen or R, w is an integer from 1 to 10, and R 1 , R 2 , and R 3are independently -CO2H, -SO3H, -OSO3H, -OH, -(OCH2CHR 0 ) w R, R are selected from C1-C6 alkyl and aryl, optionally substituted with one or more hydrophilic substituents selected from -OH, -CONH2, -SOR, and SOR, and salts thereof; 0 , and w are as defined above.

[0017] Preferably, R a is selected from the group consisting of, but not limited to, -C(CH3)2-CH2CH2-CO2H, -CH(CH3)CO2H, -CH(CO2H)CH2CO2H, -C(CH3)2CO2H, -CH2(C6H5), -C(CN)(CH3)CO2H, -C(CN)(CH3)CH2CH2CO2H.

[0018] As used herein, the terms "aryl" and "heteroaryl" refer to any substituent that contains or consists of one or more aromatic or heteroaromatic rings, respectively, and is attached by a ring atom. The ring may be a monocyclic or polycyclic ring system, with monocyclic or bicyclic 5- or 6-membered rings being preferred. The term "alkyl", used alone or in combination, such as in "alkenyloxyalkyl", "alkylthio", "alkylamino", and "dialkylamino", refers to straight-chain, branched, or cyclic alkyl, preferably C1-C6. 20 The term "alkoxy" refers to straight or branched chain alkoxy, preferably C1-C 20 The term "alkenyl" refers to an ethylenically mono-, di- or polyunsaturated alkyl or cycloalkyl group as defined above, preferably C2-C6. Examples of alkoxy include methoxy, ethoxy, n-propoxy, isopropoxy and the various butoxy isomers. The term "alkenyl" refers to an ethylenically mono-, di- or polyunsaturated alkyl or cycloalkyl group as defined above, preferably C2-C6. 20The term "acyl" refers to a group formed from a straight-chain, branched-chain or cyclic alkene, including alkenyl. The term "acyl" alone or in combination, such as "acyloxy", "acylthio", "acylamino" or "diacylamino", refers to carbamoyl, aliphatic acyl groups, and acyl groups containing an aromatic ring, referred to as aromatic acyl, or containing a heterocyclic ring, referred to as heterocyclic acyl, preferably C1-C6. 20 Indicates acyl.

[0019] The reagent (R) of formula (I) according to this first aspect is a RAFT agent of formula (II) [ka] (In the formula, R a and Z are as defined in formula (I)), and in the presence of a radical initiator, followed by polymerizing at least one monomer (A) in the presence of an intermediate prepolymer and in the presence of a radical initiator, followed by polymerizing at least one monomer (B) in the presence of said intermediate prepolymer and in the presence of a radical initiator.

[0020] As noted above, monomer (A) is at least one ethylenically unsaturated monomer having hydrophilic properties, and monomer (B) is at least one ethylenically unsaturated monomer having hydrophobic properties, but the terms "hydrophilic" and "hydrophobic" are used throughout this specification in their commonly recognized sense, i.e., to refer to compounds and / or functional moieties of compounds that "have a tendency to interact with or dissolve in water" (hydrophilic) or "are unable to interact with or dissolve in water" (hydrophobic).

[0021] Any ethylenically unsaturated monomer that has hydrophilic properties can be used as monomer (A), said hydrophilic properties can be imparted by ionizable or non-ionizable functional groups.

[0022] The term "ionizable" as used in relation to the functional groups of monomer (A) means that said functional groups can be ionized to form cationic or anionic groups. Such functional groups can usually be ionized by loss or acceptance of a proton under acidic or basic conditions. Typically, ionizable functional groups are acidic or basic groups. For example, carboxylic acid functional groups can form carboxylate anions under basic conditions, and amine functional groups can form quaternary ammonium cations under acidic conditions. Functional groups can also be ionized by ion exchange processes.

[0023] The term "non-ionizable" as used in relation to the functional groups of monomer (A) means that said functional groups do not have ionizable functional groups, in particular, such functional groups do not have acidic or basic groups capable of losing or accepting a proton under acidic or basic conditions, but are sufficiently hydrophilic to interact with water or even to dissolve in water.

[0024] Among the non-ionizable monomers (A), mention may be made of 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, poly(ethylene oxide) methyl ether methacrylate (PEOMA), poly(ethylene oxide) methyl ether acrylate (PEOA), N,N-dimethylacrylamide, N-vinyl-2-pyrrolidone.

[0025] However, it is usually preferred that monomer (A) contains an ionizable functional group.

[0026] The ionizable functional group may be a cationic functional group or an anionic functional group.

[0027] Among the ionizable monomers (A) containing a cationic functional group, mention may be made of dimethylamino-ethyl and propyl acrylate and methacrylate, N-acryloylmorpholine, and the quaternary ammonium salts thereof.

[0028] Preferred ionizable monomers (A) are selected from among monomers having an anionic functional group or a precursor thereof.

[0029] According to such an embodiment, monomer (A) is preferably selected from the group consisting of ethylenically unsaturated monomers containing at least one carboxylic acid, sulfonic acid, sulfuric acid, phosphonic acid, phosphoric acid functional group, salts thereof, or precursors thereof.

[0030] Typically, monomer (A) according to this embodiment is a monomer that contains a functional group whose corresponding acid has an acid dissociation constant pKa of less than 6, preferably less than 5, even more preferably less than 4.

[0031] Among the monomers (A) containing at least one carboxylic acid functional group or its precursor, for example, α-β-ethylenically unsaturated carboxylic acids and corresponding anhydrides, such as acrylic acid, acrylic anhydride, methacrylic acid, methacrylic anhydride, maleic acid, maleic anhydride, fumaric acid, itaconic acid, N-methacryloylalanine, N-acryloylglycine, p-carboxystyrene, and water-soluble salts thereof, may be mentioned. Monomer precursors of carboxylic acid functional groups, such as tert-butyl acrylate or tert-butyl methacrylate, which generate carboxylic acid functional groups or their salts by hydrolysis after polymerization, may be selected. Among the monomers (A) containing at least one carboxylic acid functional group, acrylic acid or methacrylic acid may be preferred.

[0032] Among the monomers (A) which contain at least one sulfuric or sulfonic acid functional group or a precursor thereof, there are for example vinyl sulfonic acid, styrene sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 3-[N-(2-methacryloyloxyethyl)-N,N-dimethylammonio]propanesulfonic acid, 3-[N,N-dimethylvinylbenzylammonio)propanesulfonic acid, 3-[2-(N-methacrylamido)-ethyldimethylammonio]propanesulfonic acid, 3-( ... 2-(methacryloyloxy)propanesulfonic acid, 3-(acryloyloxy)propanesulfonic acid, 2-(methacryloyloxy)ethanesulfonic acid, 2-(acryloyloxy)ethanesulfonic acid, 2-methylenesuccinic acid bis(3-sulfopropyl)ester, 3-[N-(3-methacrylamidopropyl)-N,N-dimethyl]ammoniopropanesulfonic acid, 3-(2-vinylpyridinio)propanesulfonic acid, and their corresponding salts and sulfate analogs. Monomers containing precursors of sulfonic acid functional groups may be selected from, for example, n-butyl p-styrenesulfonate, neopentyl p-styrenesulfonate, which generate sulfonic acid functional groups or their salts by hydrolysis after polymerization.

[0033] Notable examples of monomers (A) comprising phosphonic acids or phosphonic acid precursors are, for example, N-methacrylamidomethylphosphonic acid ester derivatives, in particular the n-propyl ester, methyl ester, ethyl ester, n-butyl ester or isopropyl ester, as well as mono- and di-acid derivatives of these phosphonic acids, such as N-methacrylamidomethyldiphosphonic acid; N-methacrylamidoethylphosphonic acid ester derivatives, such as N-methacrylamidoethylphosphonic acid dimethyl ester or N-methacrylamidoethylphosphonic acid di(2-butyl-3,3-dimethyl) ester, as well as mono- and di-acid derivatives of these phosphonic acids, such as N-methacrylamidoethyldiphosphonic acid; N-acrylamidoethylphosphonic acid Methylphosphonic acid ester derivatives, such as N-acrylamidomethylphosphonic acid dimethyl ester, N-acrylamidomethylphosphonic acid diethyl ester, or bis(2-chloropropyl)N-acrylamidomethylphosphonate, as well as their mono- and diacid derivatives of phosphonic acids, such as N-acrylamidomethylphosphonic acid; vinylbenzylphosphonate dialkyl ester derivatives, in particular the di(n-propyl), di(isopropyl), diethyl, dimethyl, di(2-butyl-3,3'-dimethyl), and di(t-butyl) ester derivatives, as well as their mono- and diphosphonic acid alternatives, such as vinylbenzyl diphosphonic acid, 2-(4-vinylphenyl)ethanephosphonic acid diethyl;Dialkylphosphonoalkyl acrylate and methacrylate derivatives, such as 2-(acryloyloxy)ethylphosphonic acid dimethyl ester and 2-(methacryloyloxy)ethylphosphonic acid dimethyl ester, 2-(methacryloyloxy)methylphosphonic acid diethyl ester, 2-(methacryloyloxy)methylphosphonic acid dimethyl ester, 2-(methacryloyloxy)propylphosphonic acid dimethyl ester, 2-acryloyloxy)methylphosphonic acid diisopropyl ester or 2-(acryloyloxy)ethylphosphonic acid diethyl ester, and to their mono- and diphosphonic acid alternatives, such as 2-(methacryloyloxy)ethylphosphonic acid, 2-(methacryloyloxy)methylphosphonic acid, 2-(methacryloyloxy)propylphosphonic acid, 2-(acryloyloxy)propylphosphonic acid, and 2-(acryloyloxy)ethylphosphonic acid; vinylphosphonic acid, optionally substituted with cyano, phenyl, ester, or acetate groups, vinylidenephosphonic acid in the form of a salt or in the form of its isopropyl ester, or bis(2-chloroethyl)vinylphosphonate;

[0034] The ethylenically unsaturated monomer (A) may also be selected from the phosphate analogs of the phosphonate-containing monomers described above.Specific phosphate-containing monomers include 2-(methacryloyloxy)ethyl phosphate, 2-(acryloyloxy)ethyl phosphate, 2-(methacryloyloxy)propyl phosphate, 2-(acryloyloxy)propyl phosphate, and the acrylate or methacrylate of polyethylene glycol omega phosphate or the acrylate or methacrylate of polypropylene glycol omega phosphate.

[0035] Advantageously, the monomer (A) is selected from the group consisting of, but not limited to, acrylic acid, methacrylic acid, vinylphosphonic acid, vinylsulfonic acid, styrenesulfonic acid and 2-acrylamido-2-methylpropanesulfonic acid, their salts or their precursors. Particularly preferred monomers (A) are selected from acrylic acid and methacrylic acid.

[0036] Ethylenically unsaturated monomers with hydrophobic properties, referred to as monomers (B), are, for example, styrene and styrene derivatives, such as α-methylstyrene, p-methylstyrene or p-(t-butyl)styrene; alkyl esters of acrylic or methacrylic acid, such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, t-butyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate; C3-C 12 vinyl nitriles, such as acrylonitrile or methacrylonitrile; vinyl or allyl esters of carboxylic acids, such as the vinyl or allyl esters of acetic acid, propionic acid, stearic acid; vinyl halides, allyl halides, vinylidene halides, or aromatic vinyl halides, such as vinyl chloride, vinylidene chloride, or pentafluorostyrene; α-olefins, such as ethylene; conjugated diene monomers, such as butadiene, isoprene, chloroprene.

[0037] Preferred monomers (B) are in particular alkyl esters of acrylic or methacrylic acid, which have the sequence -[B] which is miscible with vinylidene fluoride polymers. m - has the added advantage of giving

[0038] RAFT Agent of Formula (I) [ka] In a preferred embodiment of the formula: R ais preferably selected from the group consisting of -C(CH3)2-CH2CH2-CO2H, -CH(CH3)CO2H, -CH(CO2H)CH2CO2H, -C(CH3)2CO2H, -CH2(C6H5), -C(CN)(CH3)CO2H, -C(CN)(CH3)CH2CH2CO2H; -[A] n - preferably represents a sequence of repeating units -A- derived from at least one monomer (A) selected from the group consisting of acrylic acid, methacrylic acid, vinylphosphonic acid, vinylsulfonic acid, styrenesulfonic acid, and 2-acrylamido-2-methylpropanesulfonic acid, salts thereof, or precursors thereof, and n is an integer of 2 to 300, preferably 2 to 250, further 3 to 200, more preferably 3 to 150, and further preferably 3 to 120; -[B] m - preferably represents a sequence of repeating units -B- derived from at least one monomer (B) selected from the group consisting of alkyl esters of acrylic acid or methacrylic acid, and m represents an integer of 2 to 300, preferably 2 to 250, further preferably 3 to 200, more preferably 3 to 150, and further preferably 3 to 120; Z is preferably selected from the group consisting of optionally substituted alkylthio groups.

[0039] In the reagent (R), the optimal balance of hydrophilicity and hydrophobicity is the sequence -[A] n -Units and arrangement-[B] m - is achieved when the molar ratio between the units of is between 0.6 and 1.4. Deviations from such range may reduce the amphiphilic character of the polymeric RAFT agent, and as a result the ability of the reagent (R) to self-assemble and stabilize the emulsion polymerization may be affected.

[0040] Usually, array - [A] n -Units and arrangement-[B] m The molar ratio between the - units is preferably 0.8 to 1.2.

[0041] The reagent (R) may be present in the aqueous medium in the form of dispersed particles having an average particle size of less than 100 nm, preferably less than 75 nm, more preferably less than 50 nm.

[0042] It has been found that particles of Reagent (R) having an average particle size of 3 to 50 nm, preferably 5 to 35 nm, are particularly effective.

[0043] In this context, the expression "average particle size" in relation to dispersed particles of a reagent (R) in an aqueous medium is intended to denote the mean diameter Dz, i.e. the scattered light intensity weighted harmonic mean particle size, also called z-mean diameter, determined in accordance with standard ISO 22412:2017, for example by using the system NanoZS from Malvern Panalytical.

[0044] The mixture (M) comprises at least one fluoromonomer or monomer (F). Typically, a monomer mixture comprising two or more fluoromonomers is used in the process of the present invention.

[0045] The expression "fluoromonomer" is used herein according to its ordinary meaning, i.e. to denote an ethylenically unsaturated monomer that contains at least one fluorine atom.

[0046] The monomer (F) is generally selected from the group consisting of: - C2-C8 perfluoroolefins, such as tetrafluoroethylene (TFE), hexafluoropropene (HFP); - C2-C8 hydrogen-containing fluoroolefins such as vinyl fluoride, 1,2-difluoroethylene, vinylidene fluoride (VDF), trifluoroethylene (TrFE), pentafluoropropylene, and hexafluoroisobutylene; - Formula CH2=CH-R f0 (In the formula, R f0 is a C1-C6 (per)fluoroalkyl or C1-C6 (per)fluorooxyalkyl having one or more ether groups; - chloro- and / or bromo- and / or iodo-C2-C6 fluoroolefins, such as chlorotrifluoroethylene (CTFE); - Formula CF2=CFOR f1 (In the formula, R f1 is C1-C6 fluoro- or perfluoroalkyl, for example -CF3, -C2F5, -C3F7), fluoroalkyl vinyl ethers according to - Formula CH2=CFOR f1 (In the formula, R f1 is C1-C6 fluoro- or perfluoroalkyl, for example -CF3, -C2F5, -C3F7); - of the formula CF2=CFOX0, where X0 is a C1-C aryl group having one or more ether groups, such as perfluoro-2-propoxy-propyl 12 Oxyalkyl or C1-C 12 fluoro-oxyalkyl vinyl ethers according to the formula (I) which are (per)fluorooxyalkyl; - Formula CF2=CFOCF2OR f2 (In the formula, R f2 is a C1-C6 fluoro- or perfluoroalkyl, for example a C1-C6 (per)fluorooxyalkyl having one or more ether groups, such as -CF3, -C2F5, -C3F7, or -C2F5-O-CF3; - Formula CF2 = CFOY0 (where Y0 is C1 to C 12 Alkyl or (per)fluoroalkyl, or C1-C 12 Oxyalkyl or C1-C 12 (per)fluorooxyalkyl, said Y groups comprising carboxylic or sulfonic acid groups in their acid, acid halide or salt form; - Fluorodioxoles of the formula [ka] (In the formula, R f3 , R f4 , R f5, R f6 are equal to or different from one another and are independently a C1-C6 fluoro- or per(halo)fluoroalkyl containing a fluorine atom, optionally one or more oxygen atoms, e.g., -CF3, -C2F5, -C3F7, -OCF3, -OCF2CF2OCF3).

[0047] Monomer (F) typically includes vinylidene fluoride (VDF). The mixture (M) may include one or more monomers (F), but in a preferred embodiment, the mixture (M) typically includes vinylidene fluoride, and it is understood that it may include one or more monomers (F) detailed above that are different from vinylidene fluoride.

[0048] The mixture (M) may contain at least one additional monomer different from the monomer (F), i.e. a fluorine-free monomer, otherwise commonly referred to as a hydrogen-containing monomer. Examples of hydrogen-containing monomers are especially C2-C8 non-fluorinated alpha-olefins (O1), in particular C2-C8 non-fluorinated alpha-olefins (O1), such as ethylene, propylene, 1-butene, diene monomers, styrene monomers, etc., with the alpha-olefins typically used as detailed above.

[0049] The process of the present invention is suitable for the production of a wide variety of fluoropolymers, such as, inter alia, non-melt processable TFE polymers (such as PTFE homopolymer and its copolymers containing small amounts of fully fluorinated comonomers), thermoplastic fluoropolymers (e.g., VDF homopolymer and its plastomeric copolymers, copolymers of ethylene with CTFE, ETFE, and mixtures thereof, thermoplastic copolymers of TFE and PAVE, thermoplastic copolymers of TFE and HFP), and fluoroelastomers, especially vinylidene fluoride (VDF) fluoroelastomers.

[0050] Specific combinations of monomers (F) which can be used as mixture (M) in the process of the invention, in particular in the preparation of fluoroelastomers, are preferably (1) Different from VDF, and (a) C2-C8 perfluoroolefins, such as tetrafluoroethylene (TFE), hexafluoropropylene (HFP); (b) Hydrogen-containing C2-C8 fluoroolefins, such as vinyl fluoride (VF), trifluoroethylene (TrFE), with the formula CH2=CH-R f (In the formula, R f is a C1-C6 perfluoroalkyl group; (c) C2-C8 chloro- and / or bromo- and / or iodo-fluoroolefins, such as chlorotrifluoroethylene (CTFE); (d) Formula CF2=CFOR f (In the formula, R f is a C1-C6 (per)fluoroalkyl group, e.g., CF3, C2F5, C3F7), (per)fluoroalkyl vinyl ether (PAVE); (e) Formula CF2=CFOX (wherein X is a C1-C 12 (per)fluorooxyalkyl vinyl ethers (perfluoro)oxyalkyl, for example, perfluoro-2-propoxypropyl); (f) Formula: [ka] (In the formula, R f3 , R f4 , R f5 , R f6 are the same or different and are independently selected from fluorine atoms and C1-C6 (per)fluoroalkyl groups, which may optionally contain one or more oxygen atoms, such as, in particular, -CF3, -C2F5, -C3F7, -OCF3, -OCF2CF2OCF3, etc., (per)fluorodioxoles, preferably perfluorodioxoles; (g) (per)fluoro-methoxy-vinyl ethers (hereinafter MOVE) having the formula: CFX2=CX2OCF2OR'' f (In the formula, R'' fis selected from linear or branched C1-C6 (per)fluoroalkyl, C5-C6 cyclic (per)fluoroalkyl, and linear or branched C2-C6 (per)fluorooxyalkyl containing 1-3 bonded oxygen atoms, X2=F, H, preferably X2 is F, R'' f is -CF2CF3 (MOVE1), -CF2CF2OCF3 (MOVE2), or -CF3 (MOVE3) (h) C2-C8 non-fluorinated olefins (OI), such as ethylene and propylene; A vinylidene fluoride (VDF)-containing monomer mixture [mixture (M VDF )];and (2) Tetrafluoroethylene (TFE)-containing monomer mixture [Mixture (M TFE )] which are different from TFE and which are monomers of classes (a), (c), (d), (e), (f), (g) as detailed above, and (i) perfluorovinyl ethers containing at least one nitrile group, such as those described in particular in U.S. Pat. Nos. 4,281,092, 5,447,993, and 5,789,489. A tetrafluoroethylene (TFE)-containing monomer mixture [mixture (M TFE )] It is.

[0051] A preferred mixture (M) for use in the method of the present invention is the above-mentioned mixture (M VDF ).

[0052] Optionally, the mixture (M) (and / or the mixture (M VDF ) are represented by the general formula: [ka] (wherein R1, R2, R3, R4, R5, and R6 are equal to or different from each other and are H, halogen, or a C1-C5 optionally halogenated group that optionally contains one or more oxygen groups; Z is a linear or branched C1-C 18 an optionally halogenated alkylene or cycloalkylene radical, or a (per)fluoropolyoxyalkylene radical The copolymer may further comprise at least one bis-olefin having the formula:

[0053] Mixture (M) (and / or Mixture (M VDF The bis-olefins (OF) optionally contained in (OF-1), (OF-1) and (OF-3) are preferably selected from the group consisting of those according to the formulae (OF-1), (OF-1) and (OF-3): [ka] (In the formula, j is an integer of 2 to 10, preferably 4 to 8; R1, R2, R3, and R4 are equal to or different from each other; and H, F, or C 1~5 an alkyl or (per)fluoroalkyl group; [ka] wherein each A is the same or different from each other and at each occurrence and is independently selected from F, Cl, and H; and each B is the same or different from each other and at each occurrence and is independently selected from F, Cl, H, and OR. B Selected from R B is a branched or straight chain alkyl radical which may be partially, substantially or completely fluorinated or chlorinated, E is a divalent group having 2 to 10 carbon atoms which may contain an ether linkage and which may be optionally fluorinated, preferably E is -(CF2) where m is an integer from 3 to 5. m- group, the preferred (OF-2) type bis-olefin is F2C=CF-O-(CF2)5-O-CF=CF2); [ka] (wherein E, A, and B are as defined above; R5, R6, and R7 are the same or different from each other; H, F, C 1~5 or C 1~5 is a (per)fluoroalkyl group.

[0054] Mixture (M) (and / or Mixture (M VDF When present in mixture (M) (and / or mixture (M)), the bis-olefin (OF) VDF )) is present in an amount of 0.01 to 1 mol % based on the total amount of monomers.

[0055] If the process is used for the preparation of elastomers, the following mixtures (M) can be advantageously used (in mol %): (i) vinylidene fluoride (VDF) 35-85%, hexafluoropropene (HFP) 10-45%, tetrafluoroethylene (TFE) 0-30%, (per)fluoroalkyl vinyl ether (PAVE) 0-15%, bis-olefin (OF) 0-5%; (ii) vinylidene fluoride (VDF) 50-80%, (per)fluoroalkyl vinyl ether (PAVE) 5-50%, tetrafluoroethylene (TFE) 0-20%, bis-olefin (OF) 0-5%; (iii) 20-30% vinylidene fluoride (VDF), 10-30% C2-C8 non-fluorinated olefins (Ol), 18-27% hexafluoropropene (HFP) and / or (per)fluoroalkyl vinyl ethers (PAVE), 10-30% tetrafluoroethylene (TFE), 0-5% bis-olefins (OF); (iv) tetrafluoroethylene (TFE) 50-80%, (per)fluoroalkyl vinyl ether (PAVE) 20-50%, bis-olefin (OF) 0-5%; (v) Tetrafluoroethylene (TFE) 45-65%, C2-C8 non-fluorinated olefins (Ol) 20-55%, vinylidene fluoride (VDF) 0-30%, bis-olefins (OF) 0-5%; (vi) 32-60% mol% tetrafluoroethylene (TFE), 10-40% C2-C8 non-fluorinated olefins (Ol), 20-40% (per)fluoroalkyl vinyl ethers (PAVE), 0-30% fluorovinyl ethers (MOVE), 0-5% bis-olefins (OF); (vii) Tetrafluoroethylene (TFE) 33-75%, (per)fluoroalkyl vinyl ether (PAVE) 15-45%, vinylidene fluoride (VDF) 5-30%, hexafluoropropene HFP 0-30%, bis-olefin (OF) 0-5%; (viii) Vinylidene fluoride (VDF) 35-85%, (per)fluoro-methoxy-vinyl ether (MOVE) 5-40%, (per)fluoroalkyl vinyl ether (PAVE) 0-30%, tetrafluoroethylene (TFE) 0-40%, hexafluoropropene (HFP) 0-30%; bis-olefin (OF) 0-5%; (ix) Tetrafluoroethylene (TFE) 20-70%, (per)fluoro-methoxy-vinyl ether (MOVE) 30-80%, (per)fluoroalkyl vinyl ether (PAVE) 0-50%, bis-olefin (OF) 0-5%.

[0056] In said mixtures, the expressions (per)fluoroalkyl vinyl ether (PAVE), bis-olefin (OF), (per)fluoromethoxy vinyl ether (MOVE), C2-C8 non-fluorinated olefin (OI) have the meanings defined above.

[0057] Mixtures of types (i), (ii), (iii), (v) (VDF greater than 0), (vii) and (viii) (M VDF ) are particularly preferred for use in the methods of the present invention.

[0058] Furthermore, the mixture (M) (and / or the mixture (M VDF When )) is intended to produce a fluoroelastomer by the process of the present invention, cure site monomers can be used.

[0059] Among the cure site monomers are: (CSM-1) Iodine or bromine containing monomers of the formula: [ka] (In the formula, each A Hf are the same or different from each other and at each occurrence and are independently selected from F, Cl, and H; B Hf is F, Cl, H, OR Hf B Either Hf B is a branched or straight chain alkyl radical which may be partially, substantially or fully fluorinated or chlorinated, and each W Hf are the same or different in each occurrence and are independently a covalent bond or an oxygen atom; E Hf is a divalent group having 2 to 10 carbon atoms which may be optionally fluorinated, R Hf is a branched or linear alkyl radical which may be partially, substantially or fully fluorinated; R Hf is a halogen atom selected from the group consisting of iodine and bromine, an ether bond may be inserted, and preferably E is -(CF2) where m is an integer of 3 to 5. m- (based on); (CSM-2) optionally fluorinated ethylenically unsaturated compounds containing nitrile groups; Examples include:

[0060] Among the (CSM1) type cure site monomers, preferred monomers are (CSM1-A) Iodine or bromine-containing monomers of the formula: [ka] (In the formula, m is an integer of 0 to 5, and n is an integer of 0 to 3, but at least one of m and n is not 0, and R fiis an F or CF group (as described in particular in U.S. Pat. No. 4,745,165 (AUSIMONT SPA) 5 / 17 / 1988, U.S. Pat. No. 4,564,662 (MINNESOTA MINING) 1 / 14 / 1986, and in European Patent Application Publication No. 199138A (DAIKIN IND LTD) 10 / 29 / 1986); (CSM-1B) Iodine-containing ethylenically unsaturated compounds of the formula: CX 1 X 2 =CX 3 -(CF2CF2) p -I(wherein, X 1 , X 2 , and X 3 are the same or different from one another and are independently H or F, and p is an integer from 1 to 5, among which CH2=CHCF2CF2I, I(CF2CF2)2CH=CH2, ICF2CF2CF=CH2, I(CF2CF2)2CF=CH2 can be mentioned; (CSM-1C) Iodine-containing ethylenically unsaturated compounds of the formula: CHR=CH-Z-CHCHR-I, where R is H or CH and Z is a linear or branched C1-C aryl group optionally containing one or more ether oxygen atoms. 18 (per)fluoroalkylene radicals or (per)fluoropolyoxyalkylene radicals, among which mention may be made of CH2=CH-(CF2)4CH2CH2I, CH2=CH-(CF2)6CH2CH2I, CH2=CH-(CF2)8CH2CH2I, CH2=CH-(CF2)2CH2CH2I; (CSM-1D) Bromo and / or iodo alpha-olefins containing 2 to 10 carbon atoms, such as bromotrifluoroethylene or bromotetrafluorobutene, as described, for example, in U.S. Pat. No. 4,035,565 (DU PONT) 7 / 12 / 1977, or other compounds as disclosed in U.S. Pat. No. 4,694,045 (DU PONT) 9 / 15 / 1987; is selected from the group consisting of:

[0061] Among the cure site monomers of the (CSM2) type, preferred monomers are: (CSM2-A) Formula CF2=CF-(OCF2CFX CN ) m -O-(CF2) n -CN, X CN is a F or CF3 group, m is 0, 1, 2, 3, or 4, and n is an integer of 1 to 12; (CSM2-B) Formula CF2=CF-(OCF2CFX CN ) m’ -O-CF2-CF(CF3)-CN, X CN is an F or CF3 group, and m' is perfluorovinyl ethers containing 0, 1, 2, 3, or 4 cyanide groups; The compound is selected from the group consisting of:

[0062] Specific examples of cure site monomers of the CSM2-A and CSM2-B types suitable for the purposes of the present invention are in particular those described in U.S. Pat. No. 4,281,092 (DU PONT) 7 / 28 / 1981, U.S. Pat. No. 4,281,092 (DU PONT) 7 / 28 / 1981, U.S. Pat. No. 5,447,993 (DU PONT) 9 / 5 / 1995, and U.S. Pat. No. 5,789,489 (DU PONT) 8 / 4 / 1998.

[0063] In addition, in the method of the present invention, the aqueous medium comprises: - iodized and / or brominated chain transfer agents (suitable chain-chain transfer agents are typically of the formula R f (I) x (Br) y It is expressed as R f is a (per)fluoroalkyl or (per)fluorochloroalkyl having 1 to 8 carbon atoms, and x and y are integers from 0 to 2 such that 1≦x+y≦2 (see, for example, U.S. Pat. No. 4,243,770 (DAIKIN IND LTD) 1 / 6 / 1981 and U.S. Pat. No. 4,943,622 (NIPPON MEKTRON KK) 7 / 24 / 1990); and - alkali metal or alkaline earth metal iodides and / or bromides, such as in particular those described in US Pat. No. 5,173,553 (AUSIMONT SRL) 12 / 22 / 1992; The present invention may additionally include any one of the following:

[0064] The iodized and / or brominated chain transfer agents detailed above are particularly preferred.

[0065] These agents are particularly useful for the purpose of including additional iodine and / or bromine cure sites as end groups of the polymer (F).

[0066] The step of polymerizing mixture (M) can be carried out at a temperature of from 10 to 150° C., preferably from 20 to 110° C., and typically at a pressure of from 2 to 30 bar, in particular from 15 to 30 bar.

[0067] The temperature can be varied during the step of polymerizing the monomer (M), for example to influence the molecular weight distribution, i.e. to obtain a broad molecular weight distribution or to obtain a bimodal or multimodal molecular weight distribution.

[0068] The pH of the aqueous medium in the step of polymerizing the mixture (M) may be in the range of pH 2-10, preferably 3-9, and most preferably 4-8.

[0069] Aqueous emulsion polymerization is typically initiated by a radical initiator, including any of the initiators known to initiate free radical polymerization of fluorinated monomers. Suitable initiators include peroxides and azo compounds as well as redox-based initiators. Specific examples of peroxide initiators include hydrogen peroxide, sodium or barium peroxide, diacyl peroxides such as diacetyl peroxide, disuccinyl peroxide, dipropionyl peroxide, dibutyryl peroxide, dibenzoyl peroxide, benzoylacetyl peroxide, diglutaric acid peroxide and dilauryl peroxide, as well as peracids and their salts, such as ammonium, sodium or potassium salts. Examples of peracids include peracetic acid. Esters of peracids can be used as well, examples of which include tert-butyl peroxyacetate and tert-butyl peroxypivalate. Examples of inorganics include, for example, persulfuric acid, ammonium-alkali- or alkaline earth salts of permanganic acid or manganic acid, or manganic acid. A persulfate initiator, such as ammonium persulfate (APS), may be used alone or in combination with a reducing agent. Similarly, an organic radical initiator may be used alone or in combination with a reducing agent. The technique of combining a radical initiator with a reducing agent is generally called "redox" technique.

[0070] Suitable reducing agents for the redox technique include bisulfites, such as ammonium bisulfite or sodium metabisulfite, thiosulfates, such as ammonium, potassium, or sodium thiosulfate, hydrazine, azodicarboxylate, and azodicarboxyldiamide (ADA). Metal salt catalysts, such as copper, iron, or silver salts, may be added. Further reducing agents that may be used include sodium formaldehyde sulfoxylate (Rongalit) or fluoroalkylsulfinates, as disclosed in U.S. Pat. No. 5,285,002. Compounds having at least one sulfinic acid group may also be used as reducing agents, such as compounds of the formula: [ka] (In the formula, - M is a hydrogen atom, an ammonium ion, or a monovalent metal ion; - R20 is -OH or -N(R4)(R5), where each of R4 and R5 is the same or different from each other and is a hydrogen atom or a linear or branched alkyl chain having 1 to 6 carbon atoms; - R21 is a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, a 5- or 6-membered cycloalkyl group, a 5- or 6-membered aryl group; - R22 is -COOM, -SO3M, -C(=O)R4, -C(=O)N(R4)(R5), -C(=O)OR4; (M, R4, and R5 are as defined above.) This type of reducing agent is particularly advantageous when used in combination with an organic radical initiator, as described in U.S. Pat. No. 11,180,592.

[0071] The reducing agent is usually understood to shorten the half-life of the radical initiator and thus allow, inter alia, faster reaction rates and / or polymerization at lower temperatures.

[0072] The step of terminating the polymerization can be carried out according to known means, for example, by venting unreacted gaseous monomers, by reducing the temperature, by discontinuing further addition of initiator, and / or any combination thereof.

[0073] As a result of the process of the invention, a latex of a fluoropolymer [polymer (F)] is obtained.

[0074] The method of the present invention is particularly applicable to the preparation of fluoroelastomers. The expression "fluoroelastomer" is intended to refer to fluoropolymer resins that serve as the basic building block for obtaining true elastomers, said fluoropolymer resins comprising more than 10% by weight, preferably more than 30% by weight, of repeat units derived from at least one fluoromonomer as defined above.

[0075] A true elastomer is defined by ASTM Special Technical Bulletin, No. 184 as a material which can be stretched at room temperature to twice its original length and which, after being held under tension for five minutes, will upon release return to within 10% of its original length.

[0076] Fluoroelastomers are generally amorphous products or have a low degree of crystallinity (less than 20% by volume of crystalline phase) and a low glass transition temperature (T g In most cases, the fluoroelastomer (A) advantageously has a T of less than 10° C., preferably less than 5° C., more preferably 0° C. g and advantageously has a heat of fusion of less than 10 J / g, preferably less than 7 J / g, more preferably less than 5 J / g.

[0077] The product obtained from the process of the present invention is a fluoropolymer latex, or in other words an aqueous dispersion of fluoropolymer, which means that the polymer (F) particles are stably dispersed in the aqueous medium, so that no settling of the particles occurs within the time that the dispersion is used.

[0078] For the purposes of the present invention, the term "particle" is intended to denote, from a geometrical point of view, a mass of material having a definite three-dimensional volume and shape characterized by three dimensions, with none of said dimensions exceeding more than 1000% of the remaining two other dimensions. Particles are usually not equidimensional, i.e. they are longer in one direction than the other, and include a variety of shapes such as ellipsoids, rods, cobbles, etc.

[0079] The particles of polymer (F) in the aqueous dispersion or latex resulting from the process of the invention have an average particle size of at least 20 nm, preferably at least 30 nm, more preferably at least 50 nm, and / or at most 450 nm, preferably at most 400 nm, most preferably at most 350 nm. The average particle size of the particles of polymer (F) is measured with an apparatus based on laser light scattering, in particular photon correlation spectroscopy, equipped with a Brookhaven 2030AT model correlator from Spectra-Physics and an argon laser source with a wavelength of 514.5 nm. The latex specimens to be measured are appropriately diluted with distilled water and filtered at 0.2 μm with a Millipore filter. The scattering measurements are carried out at room temperature and at an angle of 90°. The particle size of the latex is obtained by the cumulant method.

[0080] The aqueous dispersion may be the crude polymerized latex obtained directly from the process of the present invention after the polymerization step has been completed and the unreacted monomers have been discharged, or it may be obtained from said crude polymerized latex by a post-treatment, for example a concentration method (turbidity, ultrafiltration, etc.) aimed at increasing the concentration of polymer (F) in the aqueous medium.

[0081] At the end of the process, the fluoropolymer can be treated according to known procedures to remove the chain end groups derived from the RAFT agent.

[0082] At the end of the process, the fluoropolymer can be isolated as a solid from the aqueous medium of the latex, or it can be used as a latex, i.e., as an aqueous dispersion, in which case the residual monomers are stripped before the dispersion is subsequently used.

[0083] Conventional techniques for isolating the fluoropolymer from the aqueous medium or for compounding the fluoropolymer latex can be used.

[0084] The present invention will now be described in more detail with reference to the following examples, the purpose of which is merely illustrative and not intended to limit the scope of the present invention. In the event that the disclosures of any patents, patent applications, and publications incorporated herein by reference conflict with the description of this application to the extent that a term may be unclear, the description shall control. EXAMPLES

[0085] raw materials The following materials were used in the examples: ACPA: 4,4'-azobis-4-cyanopentanoic acid (purity >98%, Merck) CTBPA: 4-cyano-4-thiothiobutylsulfanylpentanoic acid (purity = 96%, DSK Innosciences) MAA: methacrylic acid (purity >99%, Merck) MMA: Methyl methacrylate (Aldrich, purity >99%, Merck)

[0086] Preparation Example 1: Synthesis of polymeric reagent (R) Step 1a: PMAA-TTC mCTA A 0.5 L glass reactor equipped with a double jacket, mechanical stirrer, and condenser was charged with 353 g of deionized water, 1.54 g of 4,4'-azobis(4-cyanopentanoic acid) (ACP), 100 g of methacrylic acid (MAA), and 16.35 g of 4-cyano-4-thiothiobutylsulfanylpentanoic acid (CTBPA). The reactor was closed and the mixture was deoxygenated by bubbling nitrogen for 30 min. The temperature in the reactor was then raised to 80°C and maintained at this temperature for 3 h. The mixture was then cooled to 25°C and a yellow solution of polymeric chain transfer agent (mCTA) PMAA-TTC was withdrawn. The solid content of the resulting yellow solution was measured by thermogravimetry. The content and molecular weight of residual MAA were determined by HPLC and GPC, respectively.

[0087] The reaction scheme is shown below: [ka]

[0088] Process 1b: PMAA-PMMA-TTC A 0.5 L glass reactor equipped with a double jacket, a mechanical stirrer and a condenser was charged with 300 g of deionized water and 80.1 g of PMAA-TTC aqueous solution. The reactor was closed and the mixture was deoxygenated by blowing nitrogen through it for 30 minutes. The temperature in the reactor was then raised to 80° C. in 30 minutes, and when the temperature in the reactor reached 80° C., 7.2 g of methyl methacrylate (MMA) was added in small portions. An aqueous solution (40.25 g) containing 0.51 g of ACP and 0.58 g of NaHCO3 was added in small portions. The mixture was then maintained at 80° C. for 2 hours. The mixture was cooled to 25° C. and a yellow dispersion was drawn off.

[0089] The solid content (SC) of the dispersion was measured by thermogravimetry as indicated above, and the particle size (Dz) was measured by dynamic light scattering (DLS) (SC = 13-14 wt%, Dz = 12-13 nm).

[0090] The reaction scheme is shown below: [ka]

[0091] Example 2 A previously degassed 5 L vertical autoclave equipped with a stirrer operating at 630 RPM was charged with 3.0 L of demineralized water. 30.0 g of polymeric reagent (R) from preparation example 1 (concentration 13.9% by weight) were added to the reactor. The autoclave was then heated to 80° C. and maintained at such temperature for the entire duration of the reaction. The pressure of the autoclave increased by 10.7 bar by feeding HFP monomer. The autoclave was fed with a gaseous mixture of the following monomers: 70.5 mol % vinylidene fluoride (VDF), 18.5 mol % hexafluoropropene (HFP), 11.0 mol % tetrafluoroethylene (TFE). Then 2.87 g of C4F8I2 and 0.23 g of bis-olefin of formula CH2=CH-(CF2)6-CH=CH2 (hereinafter bis-olefin) were charged. Finally, 250 mL of aqueous ammonium persulfate (APS) solution (52 g / L) was charged. After the start of polymerization, a VDF / HFP / TFE mixture was continuously fed to maintain a constant pressure of 26 bar and a total of 4.07 g of bis-olefin was added in 19 stages. When about 260 g of the monomer mixture was converted, 4.5 g of C4F8I2 was added. When 1040 g of the monomer mixture was converted, a final aliquot of 2.46 g of C4F8I2 was charged.

[0092] The polymerization was continued until the total monomer consumption reached 1300 g after 115 min. At this point, the stirring was stopped, the autoclave was cooled and depressurized, and the latex was removed and degassed. The solids content obtained was 30.3 wt%. The average particle size measured by LLS was 209 ± 3 nm (PDI = 0.06). An internal stability test performed on 300 mL of the latex showed that the solids content was reduced by 5% from the initial solids value after 120 min. This indicates that the stability of the latex is very good. After coagulation with Al2(SO4)3 solution and drying in an oven at 90 °C, a Mooney viscosity of 25.1 MU (1 + 10 @ 120 °C) was obtained. The polymer composition determined by NMR was 68.2 mol% VDF, 21.1 mol% HFP, and 10.7 mol% TFE. The polymer chain ends were also determined by NMR and were quantified as follows: 17 mmol / Kg -CF2H, 3 mmol / Kg -CF2CH3, 27 mmol / Kg -CH2I, and 6 mmol / Kg -CH2OH.

[0093] Comparative Example 3 A previously degassed 5 L vertical autoclave equipped with a stirrer operating at 630 RPM was charged with 3.0 L of demineralized water. The autoclave was then heated to 80° C. and maintained at such temperature for the entire duration of the reaction. The pressure of the autoclave increased by 10.6 bar by feeding the HFP monomer. The autoclave was fed with a gaseous mixture of the following monomers to a pressure of 26 bar: 48.5 mol % vinylidene fluoride (VDF), 26.5 mol % hexafluoropropene (HFP), 25.0 mol % tetrafluoroethylene (TFE). Then 1.63 g of C4F8I2 and 0.23 g of bis-olefin were charged. Finally, 40 mL of an aqueous solution of APS (25 g / L) was charged. After the start of the polymerization, a VDF / HFP / TFE mixture was continuously fed to maintain a constant pressure of 26 bar, and a total of 4.07 g of bis-olefin was added in 19 stages. When approximately 240 g of the monomer mixture had been converted, 5.3 g of C4F8I2 was added. When approximately 960 g of the monomer mixture had been converted, a final aliquot of 4.5 g of C4F8I2 was charged.

[0094] The polymerization was continued until the total monomer consumption reached 1200 g after 275 min. At this point, the stirring was stopped, the autoclave was cooled and depressurized, and the latex was removed and degassed. The solids content obtained was 24.0 wt.%. The average particle size measured by LLS was 236±7 nm (PDI=0.03). An internal stability test performed on 300 mL of the latex showed that after 90 min the solids content was reduced by 40% from the initial solids value, indicating poor stability of the latex. After coagulation with Al2(SO4)3 solution and drying in an oven at 90 °C, a Mooney viscosity of 33.8 MU (1+10@120 °C) was obtained. The polymer composition determined by NMR was 52.5 mol% VDF, 21.9 mol% HFP, and 25.6 mol% TFE. The polymer chain ends were also determined by NMR and were quantified as follows: 5 mmol / Kg -CF2H, 25 mmol / Kg -CH2I, and 5 mmol / Kg -CH2OH.

[0095] Comparative Example 4 A previously degassed 5 L vertical autoclave equipped with a stirrer operating at 630 RPM was charged with 3.0 L of demineralized water. The autoclave was then heated to 80° C. and maintained at such temperature for the entire duration of the reaction. The pressure of the autoclave increased by 10.7 bar by feeding the HFP monomer. The following gaseous mixture of monomers was fed to the autoclave so that the pressure was 26 bar: 70.5 mol % vinylidene fluoride (VDF), 18.5 mol % hexafluoropropene (HFP), 11.0 mol % tetrafluoroethylene (TFE). Then 1.93 g of C4F8I2 and 0.21 g of bis-olefin were charged. Finally, 90 mL of an aqueous solution of APS (50 g / L) was charged. After the start of the polymerization, a VDF / HFP / TFE mixture was continuously fed to maintain a constant pressure of 26 bar, and a total of 4.08 g of bis-olefin was added in 19 stages. When approximately 260 g of the monomer mixture had been converted, 5.79 g of C4F8I2 was added. When approximately 1040 g of the monomer mixture had been converted, a final aliquot of 5.15 g of C4F8I2 was charged.

[0096] The polymerization was continued until the total monomer consumption reached 1300 g after 89 min. At this point, the stirring was stopped, the autoclave was cooled and depressurized, and the latex was removed and degassed. The solids content obtained was 31.0 wt.%. The average particle size measured by LLS was 344 ± 8 nm (PDI = 0.08). An internal stability test performed on 300 mL of the latex showed that after 120 min, the solids content was reduced by 32% from the initial solids value, indicating that the stability of the latex was insufficient. After coagulation with Al2(SO4)3 solution and drying in an oven at 90 °C, a Mooney viscosity of 29.3 MU (1 + 10 @ 120 °C) was obtained. The polymer composition determined by NMR was 68.8 mol % VDF, 20.1 mol % HFP, and 11.1 mol % TFE. The polymer chain ends were also determined by NMR and were quantified as follows: 17 mmol / Kg -CF2H, 24 mmol / Kg -CH2I, 3 mmol / Kg -CF2CH3, and 4 mmol / Kg -CH2OH.

[0097] Comparative Example 5 A previously degassed 22 L vertical autoclave equipped with a stirrer operating at 500 RPM was charged with 11.0 L of demineralized water. The autoclave was then heated to 80° C. and maintained at such temperature for the entire duration of the reaction. The pressure of the autoclave increased by 10.7 bar by feeding the HFP monomer. The autoclave was fed with a gaseous mixture of the following monomers to a pressure of 26 bar: 70.5 mol % vinylidene fluoride (VDF), 18.5 mol % hexafluoropropene (HFP), 11.0 mol % tetrafluoroethylene (TFE). 8.15 g of C4F8I2 and 0.92 g of bisolefin were then charged. 50 mL of an aqueous solution of APS (20 g / L) was then charged. An aqueous solution of t-BHP (7.0 g / L) and an aqueous solution of Bruggolite E28 (2.0 g / L) were introduced separately but simultaneously into the reactor with nominal flow rates of 92 mL / h and 795 mL / h, respectively. Their feeds were kept constant throughout the reaction. After the start of polymerization, a VDF / HFP / TFE mixture was continuously fed to maintain a constant pressure of 26 bar and a total of 17.4 g of bis-olefin was added in 19 stages. When 1104 g of the monomer mixture had been converted, 24.0 g of C4F8I2 was added. When 4416 g of the monomer mixture had been converted, a final aliquot of 21.9 g of C4F8I2 was charged.

[0098] The polymerization was continued until the total monomer consumption reached 5520 g after 218 min, at which time a total of 375 mL of t-BHP solution and 2955 mL of Bruggolite E28 solution were added. At this point, the stirring was stopped, the autoclave was cooled and depressurized, and the latex was removed and degassed. The solids content obtained was 29.6 wt%. The average particle size measured by LLS was 398 ± 5 nm (PDI = 0.05). The latex was diluted to 20% solids with demineralized water, and an internal stability test was performed with 300 mL of the diluted latex, showing that the solids content after 120 min was 53% lower than the initial solids value. Thus, the stability of the latex was insufficient. After coagulation with Al2(SO4)3 solution and drying in an oven at 90 °C, a Mooney viscosity of 19 MU (1 + 10 @ 120 °C) was obtained. The polymer composition determined by NMR was 69.2 mol% VDF, 19.3 mol% HFP, 11.5 mol% TFE. The polymer chain ends were also determined by NMR and quantified as follows: 13 mmol / Kg -CF2H, 33 mmol / Kg -CH2I, 3 mmol / Kg -CF2CH3, and less than 1 mmol / Kg -CH2OH.

[0099] Example 2 A previously degassed 22 L vertical autoclave equipped with a stirrer operating at 500 RPM was charged with 12.5 L of demineralized water. 43 g of seed dispersion (concentration 13.9 wt.%) was added to the reactor. The autoclave was then heated to 80° C. and maintained at such temperature for the entire duration of the reaction. The pressure of the autoclave increased by 10.7 bar by feeding HFP monomer. A gaseous mixture of the following monomers was fed to the autoclave to a pressure of 26 bar: vinylidene fluoride (VDF) 70.5 mol %, hexafluoropropene (HFP) 18.5 mol %, tetrafluoroethylene (TFE) 11.0 mol %. 8.75 g of C4F8I2 was then charged. Afterwards, 50 mL of an aqueous solution of APS (20 g / L) was charged. Finally, an aqueous solution of t-BHP (9.5 g / L) and an aqueous solution of Bruggolite E28 (23.6 g / L) were introduced separately but simultaneously into the reactor at a nominal flow rate of 75 mL / h. The respective feeds were kept constant throughout the reaction. After the start of polymerization, a VDF / HFP / TFE mixture was continuously fed to maintain a constant pressure of 26 bar and a total of 19.9 g of bis-olefin was added in 20 stages. When 1200 g of the monomer mixture had been converted, 26.2 g of C4F8I2 was added. When 4800 g of the monomer mixture had been converted, a final aliquot of 23.3 g of C4F8I2 was charged.

[0100] The polymerization was continued until the total monomer consumption reached 6000 g after 373 min, at which time a total of 455 mL of t-BHP solution and 455 mL of Bruggolite E28 solution were added. At this point, the stirring was stopped, the autoclave was cooled and depressurized, and the latex was removed and degassed. The resulting solids content was 32.0 wt%. The average particle size measured by LLS was 251 ± 8 nm (PDI = 0.05). The latex was diluted to 20% solids with demineralized water, and an internal stability test was performed with 300 mL of the diluted latex, showing that the solids content after 120 min was 17% lower than the initial solids value. This is considered to be a relatively good latex stability. After coagulation with Al2(SO4)3 solution and drying in an oven at 90 °C, a Mooney viscosity of 26 MU (1 + 10 @ 120 °C) was obtained. The polymer composition determined by NMR was 69.5 mol% VDF, 19.0 mol% HFP, 11.4 mol% TFE. The polymer chain ends were also determined by NMR and quantified as follows: 13 mmol / Kg -CF2H, 29 mmol / Kg -CH2I, 2 mmol / Kg -CF2CH3, and less than 1 mmol / Kg -CH2OH.

Claims

1. 1. A process for emulsion polymerization of at least one fluoromonomer, comprising the steps of: A monomer mixture [mixture (M)] comprising at least one fluoromonomer [mixture (F)] and optionally at least one additional monomer is reacted with a monomer mixture of formula (I): 【Chemistry 1】 Amphiphilic polymer RAFT agent [Reagent (R)] (In the formula, R ａ is an organic group optionally substituted with one or more hydrophilic groups; -[A] ｎ - represents a sequence of repeating units -A- derived from at least one ethylenically unsaturated monomer having hydrophilicity [monomer (A)], and n represents an integer of 2 to 300, preferably 2 to 250, further 3 to 200, more preferably 3 to 150, and further preferably 3 to 120; -[B] ｍ - represents a sequence of repeating units -B- derived from at least one ethylenically unsaturated monomer having hydrophobicity [monomer (B)], and m represents an integer of 2 to 300, preferably 2 to 250, further 3 to 200, more preferably 3 to 150, and further preferably 3 to 120; Z is optionally substituted alkoxy, optionally substituted aryloxy, optionally substituted heterocyclyl, optionally substituted alkylthio, optionally substituted arylalkylthio, dialkoxy- or diaryloxy-phosphinyl [-P(=O)(OR ４ ) ２ ], dialkyl- or diarylphosphinyl [-P(=O)R ４ ２ ], R ４ is optionally substituted C １ ~C １８ Alkyl, optionally substituted C ２ ~C １８ is selected from the group consisting of alkenyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted aralkyl, optionally substituted alkaryl, optionally substituted acylamino, optionally substituted acylimino, optionally substituted amino, polymer chains formed by any mechanism; Z is optionally substituted alkyl, preferably optionally substituted C １ ~C ２０ R may be further selected from the group consisting of alkyl, optionally substituted aryl, and optionally substituted arylalkyl; ４ and optional substituents for the Z group include epoxy, hydroxy, alkoxy, acyl, acyloxy, carboxy (and its salts), sulfonic acid (and its salts), alkoxy- or aryloxy-carbonyl, isocyanato, cyano, silyl, halo, and dialkylamino. and polymerizing in an aqueous medium comprising - Terminating the polymerization and recovering the latex of the fluoropolymer [polymer (F)]. The method includes:

2. Z is -R ５ , -OR ５ , -SR ５ (In the formula, R ５ is optionally substituted C １ ~C ２０ alkyl); -NR ５ R ６ (In the formula, R ５ is as defined, and R ６ is optionally substituted C １ ~C ２０ and alkyl, optionally substituted aryl; and 【Chemistry 2】 (wherein e is an integer from 2 to 4). and / or Z is selected from the group consisting of -OR ５ , -SR ５ (In the formula, R ５ is optionally substituted C １ ~C ２０ alkyl); -NH ５ R ６ (In the formula, R ５ is as defined, and R ６ is optionally substituted C １ ~C ２０ and alkyl, optionally substituted aryl; and 【Chemistry 3】 (wherein e is an integer from 2 to 4). and / or Z is selected from the group consisting of -SCH ２ (C ６ H ５ ), -S(CH ２ ) ｕ CO ２ H (wherein u is an integer from 2 to 11), —OC ｚ H ２ｚ＋１ , -SC ｚ H ２ｚ＋１ (wherein z is an integer from 1 to 12, preferably an integer from 2 to 12), -SCH ２ CH ２ OH, -OCH ２ CF ３ , -N(C ６ H ５ ) (CH ３ and / or R ａ But, C １ ~C ６ Alkyl, C １ ~C ６ alkoxy, aryl, or heteroaryl, each of which is selected from -CO ２ H, -CO ２ R, -CN, -SO ３ H, -OSO ３ H, -SOR, -SO ２ R, -OP(OH) ２ , -P(OH) ２ , -PO(OH) ２ , -OH, -OR, -(OCH ２ -CHR ０ ) ｗ -OH, -(OCH ２ -CHR ０ ) ｗ -OR, -CONH ２ , C.O.N.R. １ , C.O.R. １ R ２ , -NR １ R ２ , -NR １ R ２ R ３ and R is optionally substituted with one or more hydrophilic groups selected from １ ~C ６ alkyl; R ０ is selected from hydrogen or R, w is an integer from 1 to 10, and R １ , R ２ , and R ３ is independently -CO ２ H, -SO ３ H, -OSO ３ H, -OH, -(OCH ２ CHR ０ ) ｗ -OH, -CONH ２ , -SOR, and SO ２ R, and salts thereof. １ ~C ６ alkyl and aryl; R, R ０ and w is as defined above; and / or R ａ but is not limited to -C(CH ３ ) ２ -CH ２ CH ２ -CO ２ H, -CH(CH ３ ) CO ２ H, -CH(CO ２ H) CH ２ CO ２ H, -C(CH ３ ) ２ CO ２ H, -CH ２ (C ６ H ５ ), -C(CN)(CH ３ ) CO ２ H, -C(CN)(CH ３ ) CH ２ CH ２ CO ２ H; The method of claim 1.

3. The reagent (R) of formula (I) is a RAFT agent of formula (II): 【Chemistry 4】 (In the formula, R ａ and Z are as defined in formula (I) of claim 1 or 2), and in the presence of a radical initiator, followed by polymerizing at least one monomer (A) in the presence of said intermediate prepolymer and in the presence of a radical initiator; and / or the method according to claim 1 or 2, wherein the reagent (R) is present in the form of particles having an average particle size of 3 to 50 nm, preferably 5 to 35 nm, measured as the mean diameter Dz, i.e. the scattered light intensity weighted harmonic mean particle size, also called the z-mean diameter, determined according to standard ISO 22412:2017.

4. The method according to any one of claims 1 to 3, wherein the monomer (A) comprises an ionizable functional group; and / or the monomer (A) comprises an ionizable functional group selected from the group consisting of a cationic functional group or an anionic functional group.

5. 5. The method of claim 4, wherein the monomer (A) comprises a cationic functional group and / or the monomer (A) comprises at least one of dimethylamino-ethyl and propyl acrylate and methacrylate, N-acryloylmorpholine, and quaternary ammonium salts thereof.

6. 5. The method of claim 4, wherein the monomer (A) comprises an anionic functional group and / or the monomer (A) is selected from the group consisting of ethylenically unsaturated monomers comprising at least one carboxylic acid, sulfonic acid, sulfuric acid, phosphonic acid, phosphoric acid functional group, salts thereof or precursors thereof.

7. the monomer (A) contains at least one carboxyl function or a precursor thereof and is preferably selected from the group consisting of α-β-ethylenically unsaturated carboxylic acids and the corresponding anhydrides, such as acrylic acid, acrylic anhydride, methacrylic acid, methacrylic anhydride, maleic acid, maleic anhydride, fumaric acid, itaconic acid, N-methacryloylalanine, N-acryloylglycine, p-carboxystyrene, and the water-soluble salts thereof; tert-butyl acrylate and tert-butyl methacrylate; and / or the monomer (A) contains at least one sulfuric or sulfonic acid functional group or a precursor thereof, and is preferably vinylsulfonic acid, styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 3-[N-(2-methacryloyloxyethyl)-N,N-dimethylammonio]propanesulfonic acid, 3-[N,N-dimethylvinylbenzylammonio)propanesulfonic acid, 3-[2-(N-methacrylamido)-ethyldimethylammonio]propanesulfonic acid, 3-(methacryloyloxy)propanesulfonic acid, 3- selected from the group consisting of (acryloyloxy)propanesulfonic acid, 2-(methacryloyloxy)ethanesulfonic acid, 2-(acryloyloxy)ethanesulfonic acid, 2-methylenesuccinic acid bis(3-sulfopropyl)ester, 3-[N-(3-methacrylamidopropyl)-N,N-dimethyl]ammoniopropanesulfonic acid, 3-(2-vinylpyridinio)propanesulfonic acid, and their corresponding salt and sulfate analogs, n-butyl p-styrenesulfonate, and neopentyl p-styrenesulfonate; and / or Monomer (A) comprises a phosphonic acid or a phosphonic acid precursor, preferably an N-methacrylamidomethylphosphonic acid ester derivative, in particular the n-propyl ester, methyl ester, ethyl ester, n-butyl ester or isopropyl ester, and also the mono- and di-acid derivatives of these phosphonic acids, such as N-methacrylamidomethyldiphosphonic acid; an N-methacrylamidoethylphosphonic acid ester derivative, such as N-methacrylamidoethylphosphonic acid dimethyl ester or N-methacrylamidoethylphosphonic acid di(2-butyl-3,3-dimethyl) ester, and also the mono- and di-acid derivatives of these phosphonic acids, such as N-methacrylamidoethyldiphosphonic acid; an N-acrylamidomethylphosphonic acid ester derivative, such as N-methacrylamidoethylphosphonic acid dimethyl ester or N-methacrylamidoethylphosphonic acid di(2-butyl-3,3-dimethyl) ester, and also the mono- and di-acid derivatives of these phosphonic acids, such as N-methacrylamidoethyldiphosphonic acid; vinylbenzylphosphonate dialkyl ester derivatives, such as N-acrylamidomethylphosphonic acid dimethyl ester, N-acrylamidomethylphosphonic acid diethyl ester, or bis(2-chloropropyl)N-acrylamidomethylphosphonate, as well as their mono- and diacid derivatives, such as N-acrylamidomethylphosphonic acid; vinylbenzylphosphonate dialkyl ester derivatives, in particular the di(n-propyl), di(isopropyl), diethyl, dimethyl, di(2-butyl-3,3′-dimethyl), and di(t-butyl) ester derivatives, as well as their mono- and diphosphonic acid alternatives, such as vinylbenzyl diphosphonic acid, 2-(4-vinylphenyl)ethanephosphonic acid diethyl;Dialkylphosphonoalkyl acrylate and methacrylate derivatives, such as 2-(acryloyloxy)ethyl phosphonic acid dimethyl ester and 2-(methacryloyloxy)ethyl phosphonic acid dimethyl ester, 2-(methacryloyloxy)methyl phosphonic acid diethyl ester, 2-(methacryloyloxy)methyl phosphonic acid dimethyl ester, 2-(methacryloyloxy)propyl phosphonic acid dimethyl ester, 2-acryloyloxy)methyl phosphonic acid diisopropyl ester or 2-(acryloyloxy)ethyl phosphonic acid diethyl ester, and the like. alternative forms which are mono- and diphosphonic acids of the formula (I), such as 2-(methacryloyloxy)ethylphosphonic acid, 2-(methacryloyloxy)methylphosphonic acid, 2-(methacryloyloxy)propylphosphonic acid, 2-(acryloyloxy)propylphosphonic acid and 2-(acryloyloxy)ethylphosphonic acid; vinylphosphonic acid, optionally substituted with cyano, phenyl, ester or acetate groups, vinylidenephosphonic acid in the form of a salt or in the form of its isopropyl ester, or bis(2-chloroethyl)vinylphosphonate; The method according to claim 6.

8. 8. The process according to claim 7, wherein the monomer (A) is selected from the group consisting of acrylic acid, methacrylic acid, vinylphosphonic acid, vinylsulfonic acid, styrenesulfonic acid, and 2-acrylamido-2-methylpropanesulfonic acid, their salts or precursors thereof, and the monomer (A) is preferably selected from the group consisting of acrylic acid and methacrylic acid.

9. Monomer (B) is selected from the group consisting of styrene and styrene derivatives, such as α-methylstyrene, p-methylstyrene, or p-(t-butyl)styrene; alkyl esters of acrylic or methacrylic acid, such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, t-butyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate; ３ ~C １２ 9. The process according to any one of claims 1 to 8, wherein the monomer (B) is selected from the group consisting of vinyl nitriles, such as acrylonitrile or methacrylonitrile; vinyl or allyl esters of carboxylic acids, such as the vinyl or allyl esters of acetic acid, propionic acid, stearic acid; vinyl halides, vinylidene halides, or pentafluorostyrene; α-olefins, such as ethylene; conjugated diene monomers, such as butadiene, isoprene, chloroprene; and / or alkyl esters of acrylic or methacrylic acid.

10. The method according to any one of claims 1 to 9, wherein the reagent (R) is according to formula (I): 【Chemistry 5】 (In the formula, R ａ is -C(CH ３ ) ２ -CH ２ CH ２ -CO ２ H, -CH(CH ３ ) CO ２ H, -CH(CO ２ H) CH ２ CO ２ H, -C(CH ３ ) ２ CO ２ H, -CH ２ (C ６ H ５ ), -C(CN)(CH ３ ) CO ２ H, -C(CN)(CH ３ ) CH ２ CH ２ CO ２ H; -[A] ｎ - represents a sequence of repeating units -A- derived from at least one monomer (A) selected from the group consisting of acrylic acid, methacrylic acid, vinylphosphonic acid, vinylsulfonic acid, styrenesulfonic acid, and 2-acrylamido-2-methylpropanesulfonic acid, salts thereof, or precursors thereof, and n is an integer of 2 to 300, preferably 2 to 250, further 3 to 200, more preferably 3 to 150, and further preferably 3 to 120; -[B] ｍ - represents a sequence of repeating units -B- derived from at least one monomer [monomer (B)] selected from the group consisting of alkyl esters of acrylic acid or methacrylic acid, and m represents an integer of 2 to 300, preferably 2 to 250, further preferably 3 to 200, more preferably 3 to 150, and further preferably 3 to 120; Z is selected from the group consisting of optionally substituted alkylthio groups; and / or In the reagent (R), the sequence -[A] ｎ - units and the sequence -[B] ｍ The molar ratio between the units of the sequence -[A] is 0.6 to 1.4, ｎ - units and the sequence -[B] ｍ -units is preferably from 0.8 to 1.2; and / or The reagent (R) is present in the aqueous medium in the form of dispersed particles having an average particle size Dz of less than 100 nm, preferably less than 50 nm, more preferably less than 30 nm; The method according to any one of claims 1 to 9.

11. The method according to any one of claims 1 to 10, wherein the monomer (F) is selected from the group consisting of: - Tetrafluoroethylene (TFE), hexafluoropropene (HFP), etc. ２ ~C ８ Perfluoroolefin; - C such as vinyl fluoride, 1,2-difluoroethylene, vinylidene fluoride (VDF), trifluoroethylene (TrFE), pentafluoropropylene, and hexafluoroisobutylene ２ ~C ８ hydrogen-containing fluoroolefins; - Formula CH ２ =CH-R ｆ０ (In the formula, R ｆ０ is a C having one or more ether groups １ ~C ６ (Per)fluoroalkyl or C １ ~C ６ (per)fluoroalkylethylene satisfying the formula (1); - chloro- and / or bromo- and / or iodo-C ２ ~C ６ Fluoroolefins, such as chlorotrifluoroethylene (CTFE); - Formula CF ２ =CFOR ｆ１ (In the formula, R ｆ１ is C １ ~C ６ Fluoro- or perfluoroalkyl, such as -CF ３ , -C ２ F ５ , -C ３ F ７ Fluoroalkyl vinyl ethers according to - Formula CH ２ =CFOR ｆ１ (In the formula, R ｆ１ is C １ ~C ６ Fluoro- or perfluoroalkyl, such as -CF ３ , -C ２ F ５ , -C ３ F ７ a hydrofluoroalkyl vinyl ether satisfying the formula (I); - Formula CF ２ =CFOX ０ (In the formula, X ０ is a C having one or more ether groups, such as perfluoro-2-propoxy-propyl; １ ~C １２ Oxyalkyl, or C １ ~C １２ fluoro-oxyalkyl vinyl ethers according to the formula (I) which are (per)fluorooxyalkyl; - Formula CF ２ = CFOCF ２ OR ｆ２ (In the formula, R ｆ２ is C １ ~C ６ Fluoro- or perfluoroalkyl, such as -CF ３ , -C ２ F ５ , -C ３ F ７ , or -C ２ F ５ -O-CF ３ C having one or more ether groups, such as １ ~C ６ fluoroalkyl-methoxy-vinyl ethers according to the formula (I) (per)fluorooxyalkyl; - Formula CF ２ = CFOY ０ (In the formula, Y ０ is C １ ~C １２ Alkyl or (per)fluoroalkyl, or C １ ~C １２ Oxyalkyl or C １ ~C １２ (per)fluorooxyalkyl, ０ groups include carboxylic acid groups or sulfonic acid groups in their acid, acid halide or salt form; - Fluorodioxole of the formula 【Chemistry 6】 (In the formula, R ｆ３ , R ｆ４ , R ｆ５ , R ｆ６ Each of the C groups is equal to or different from each other and independently contains a fluorine atom, optionally one or more oxygen atoms. １ ~C ６ Fluoro- or per(halo)fluoroalkyl, for example, —CF ３ , -C ２ F ５ , -C ３ F ７ , -OCF ３ , -OCF ２ CF ２ O.C.F. ３ (It is.)

12. The mixture (M) is (1) Unlike VDF, and (a) C ２ ~C ８ Perfluoroolefins, such as tetrafluoroethylene (TFE), hexafluoropropylene (HFP); (b) Hydrogen-containing C ２ ~C ８ Fluoroolefins, such as vinyl fluoride (VF), trifluoroethylene (TrFE), ２ =CH-R ｆ (In the formula, R ｆ is C １ ~C ６ perfluoroalkyl ethylenes, each of which is a perfluoroalkyl group; (c) C ２ ~C ８ Chloro- and / or bromo- and / or iodo-fluoroolefins, such as chlorotrifluoroethylene (CTFE); (d) Formula CF ２ =CFOR ｆ (In the formula, R ｆ is C １ ~C ６ (Per)fluoroalkyl groups, such as CF ３ , C ２ F ５ , C ３ F ７ (per)fluoroalkyl vinyl ethers (PAVEs) of the formula: (e) Formula CF ２ =CFOX (wherein X is a C １ ~C １２ (per)fluorooxyalkyl vinyl ethers of ((per)fluoro)-oxyalkyl, for example, perfluoro-2-propoxypropyl; (f) Formula: 【Chemistry 7】 (In the formula, R ｆ３ , R ｆ４ , R ｆ５ , R ｆ６ are the same or different and independently represent a fluorine atom, and in particular -CF ３ , -C ２ F ５ , -C ３ F ７ , -OCF ３ , -OCF ２ CF ２ O.C.F. ３ C, which may optionally contain one or more oxygen atoms, such as １ ~C ６ (per)fluorodioxoles, preferably perfluorodioxoles, having a (per)fluoroalkyl group selected from the group consisting of (g) (per)fluoro-methoxy-vinyl ethers (hereinafter MOVE) having the formula: CFX ２ =CX ２ OCF ２ OR’’ ｆ (In the formula, R'' ｆ is a straight or branched chain C １ ~C ６ (Per)fluoroalkyl, C ５ ~C ６ Cyclic (per)fluoroalkyl and linear or branched C containing 1 to 3 bonded oxygen atoms ２ ~C ６ (per)fluorooxyalkyl; X ２ = F, H, preferably X ２ is F and R'' ｆ Ha-CF ２ CF ３ (MOVE1), -CF ２ CF ２ O.C.F. ３ (MOVE2), or -CF ３ (MOVE3)) (per)fluoro-methoxy-vinyl ether: (h) C ２ ~C ８ Non-fluorinated olefins (OI), such as ethylene and propylene; A vinylidene fluoride (VDF)-containing monomer mixture [mixture (M ＶＤＦ )];and (2) Tetrafluoroethylene (TFE)-containing monomer mixture [Mixture (M ＴＦＥ ) , wherein TFE is different from TFE and is selected from monomers of classes (a), (c), (d), (e), (f), (g) as detailed above, and (i) Perfluorovinyl ethers containing at least one nitrile group A tetrafluoroethylene (TFE)-containing monomer mixture [mixture (M ＴＦＥ ) ] Preferably, the mixture (M) is selected from the group consisting of mixture (M ＶＤＦ 12. The method of claim 11 , wherein the compound is selected from the group consisting of:

13. The mixture (M) is the following mixture (M) (in mole %): (i) Vinylidene fluoride (VDF) 35-85%, hexafluoropropene (HFP) 10-45%, tetrafluoroethylene (TFE) 0-30%, (per)fluoroalkyl vinyl ether (PAVE) 0-15%, bis-olefin (OF) 0-5%; (ii) vinylidene fluoride (VDF) 50-80%, (per)fluoroalkyl vinyl ether (PAVE) 5-50%, tetrafluoroethylene (TFE) 0-20%, bis-olefin (OF) 0-5%; (iii) vinylidene fluoride (VDF) 20-30%, C ２ ~C ８ non-fluorinated olefins (Ol) 10-30%, hexafluoropropene (HFP) and / or (per)fluoroalkyl vinyl ethers (PAVE) 18-27%, tetrafluoroethylene (TFE) 10-30%, bis-olefins (OF) 0-5%; (iv) tetrafluoroethylene (TFE) 50-80%, (per)fluoroalkyl vinyl ether (PAVE) 20-50%, bis-olefin (OF) 0-5%; (v) Tetrafluoroethylene (TFE) 45-65%, C ２ ~C ８ Non-fluorinated olefin (Ol) 20-55%, vinylidene fluoride (VDF) 0-30%, bis-olefin (OF) 0-5%; (vi) tetrafluoroethylene (TFE) 32 to 60% mol%, C ２ ~C ８ Non-fluorinated olefins (Ol) 10-40%, (per)fluoroalkyl vinyl ethers (PAVE) 20-40%, fluorovinyl ethers (MOVE) 0-30%, bis-olefins (OF) 0-5%; (vii) Tetrafluoroethylene (TFE) 33-75%, (per)fluoroalkyl vinyl ether (PAVE) 15-45%, vinylidene fluoride (VDF) 5-30%, hexafluoropropene HFP 0-30%, bis-olefin (OF) 0-5%; (viii) Vinylidene fluoride (VDF) 35-85%, (per)fluoro-methoxy-vinyl ether (MOVE) 5-40%, (per)fluoroalkyl vinyl ether (PAVE) 0-30%, tetrafluoroethylene (TFE) 0-40%, hexafluoropropene (HFP) 0-30%; bis-olefin (OF) 0-5%; (ix) Tetrafluoroethylene (TFE) 20-70%, (per)fluoro-methoxy-vinyl ether (MOVE) 30-80%, (per)fluoroalkyl vinyl ether (PAVE) 0-50%, bis-olefin (OF) 0-5%, and the term bis-olefin (OF) is selected from the group consisting of the general formula: 【Chemistry 8】 (In the formula, R １ , R ２ , R ３ , R ４ , R ５ , and R ６ are equal or different from each other and are H, halogen, or C, which optionally contains one or more oxygen groups; １ ~C ５ and Z is a linear or branched C １ ~C １８ or a (per)fluoropolyoxyalkylene radical, The method of claim 12, wherein the bis-olefin has the formula:

14. The aqueous medium is at least one iodized and / or brominated chain transfer agent, preferably a compound represented by the formula R ｆ (I) a chain transfer agent selected from the group consisting of: x(Br)y, wherein R ｆ The method according to any one of claims 1 to 13, wherein x is a (per)fluoroalkyl or (per)fluorochloroalkyl containing 1 to 8 carbon atoms, x and y are integers from 0 to 2, and 1≦x+y≦2.

15. The process according to any one of claims 1 to 14, wherein the polymer (F) is a fluoroelastomer.

16. A latex obtainable by the method according to any one of claims 1 to 15.

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