EP2207826A1

EP2207826A1 - Ampholytic copolymer with controlled architecture

Info

Publication number: EP2207826A1
Application number: EP08847838A
Authority: EP
Inventors: Mathias Destarac
Original assignee: Rhodia Operations SAS
Current assignee: Rhodia Operations SAS
Priority date: 2007-11-09
Filing date: 2008-10-21
Publication date: 2010-07-21
Also published as: FR2923487B1; CA2704788A1; US20130144003A9; FR2923487A1; WO2009059887A1; KR20100085088A; SG188120A1; US20100280169A1; JP2011503273A

Abstract

The invention relates to novel ampholytic copolymers having a controlled architecture. These copolymers can particularly be used in aqueous compositions.

Description

Ampholytic copolymer with controlled architecture

The present invention relates to novel ampholytic copolymers having a controlled architecture. These copolymers can in particular be used in aqueous compositions.

The document [Lowe et al. Chem. Rev. 2002, 102, 4177] discloses block copolymers comprising a block derived from monomers comprising a tertiary amine group, and a block derived from monomers comprising a carboxylic group. This document also mentions the documents [Beturov et al. J. Makromol. Chem. 1990, 191, 457] and [Beturov et al. J. Makromol. Chem., Rapid Commun. 1992, 13, 225] as describing block copolymers comprising a block derived from 1-methyl-4-vinylpyridinium chloride and a block derived from methacrylic acid.

The document [Lowe et al. Macromolecules. 1998, 31, 5991] also discloses block copolymers comprising a block derived from monomers comprising a tertiary amine group, and a block derived from methacrylic acid. The process involves a group transfer polymerization, and involves protection and then deprotection of methacrylic acid.

The document [Vo et al. Macromolecules 2007, 40, 157; Cai et al. Macromolecules 2005, 38, 271] discloses block copolymers comprising a block derived from monomers comprising a tertiary amine group, and a block derived from monomers comprising a carboxylic group. The process employs ATRP type polymerization and post-polymerization esterification reaction with succinic anhydride to obtain carboxylic groups. The document [Gabaston et al. Polymer 1999, 40, 4505] discloses a block copolymer comprising a block derived from VBTMAC and a block derived from sodium styrene sulfonate. This copolymer is not soluble in water. The process involves polymerization with nitroxides.

The document [Xin et al. Eur. Polym. J. 2005, 41, 1539; Mertoglu et al. Polymer 2005, 46, 7726] discloses block copolymers comprising a block derived from monomers comprising a tertiary amine group, and a block derived from sodium acrylate.

There is a need for other ampholytic copolymers, especially for copolymers that can be used in aqueous compositions. In particular, there is a need for ampholytic copolymers which can bring new properties to compositions comprising a stabilized product. There is also a need for simpler preparation processes for ampholytic copolymers with controlled architecture.

The present invention satisfies at least one of the abovementioned needs by providing an ampholytic copolymer comprising at least one macromolecular chain B and at least one part A linked to one end of the macromolecular chain B, in which:

the macromolecular chain B comprises cationic units B _c , derived from cationic monomers B _c ,

- Part A is a macromolecular chain A comprising potentially anionic units A _A , derived from potentially anionic monomers A _A , characterized in that:

the units B _c comprise a quaternary ammonium group, and

the units A _A comprise a group chosen from the following groups, in acid or salified form: the carboxylic group -COO ^"

the sulphonate group -SO ₃ ^"

the sulfate group -SO ₄ ^"

the phosphonate group -PO ₃ ^{2 "}

the phosphate group -PO ₄ ^{2 "} , the A _A units being different from units derived from styrene sulphonate in acid or salified form.

The invention also relates to a process for preparing such copolymers, wherein the copolymer is a block copolymer, preferably linear, comprising at least one block A and at least one block B, where the macromolecular chain A constitutes the block A and the macromolecular chain B constitutes block B, said process comprising the following steps: step 1): polymerization, preferably by controlled radical polymerization, of monomers so as to obtain a first block chosen from block A and block B, or a block precursor of the first block, step 2): polymerization, preferably by controlled radical polymerization, of monomers so as to obtain at least a second block chosen from block A if a block B or a precursor was obtained in step 1, and block B if a block A or a precursor has been obtained in step 1), or a precursor block of the second block, step 3) optional: if precursor blocks have te obtained in steps 1) and / or 2) chemical modification of these blocks so as to obtain or block A and block B. The process of the invention is particularly simple, effective and / or economically advantageous.

The invention also relates to the use of the copolymers of the invention in compositions, for example aqueous compositions comprising a product dispersed or solubilized in the composition. The invention also relates to compositions comprising said product and the copolymer of the invention. The compositions may in particular be compositions for the treatment and / or modifications of surfaces, for example coating compositions, cosmetic compositions, compositions for the care of the laundry, compositions for cleaning the dishes, these care compositions. (cleaning for example) hard surfaces. The compositions may especially be compositions for water treatment, compositions for the building and public works, including compositions comprising a hydraulic binder. The compositions may especially be pharmaceutical or phytosanitary compositions. The invention also relates to the use of the compositions for which they are intended.

Definitions

In the present application, the term "unit derived from a monomer" denotes a unit that can be obtained directly from said monomer by polymerization. Thus, for example, a unit derived from an ester of acrylic or methacrylic acid does not cover a unit of formula -CH ₂ -CH (COOH) -, or -CH ₂ -C (CH ₃ ) (COOH) -, obtained for example by polymerizing an acrylic or methacrylic acid ester and then hydrolyzing. Thus, the terminology "unit derived from a monomer" relates only to the final constitution of the polymer and is independent of the polymerization process used to synthesize the polymer.

In the present application, the term "hydrophobic" for a monomer is used in its usual sense of "which has no affinity for water"; this means that the monomer can form a two-phase macroscopic solution in distilled water at 25 ° C, at a concentration greater than or equal to 1% by weight, or that it has been categorized as hydrophobic in the present application.

In the present application, the term "hydrophilic", for a monomer, is also used in its usual sense of "which has affinity for water", that is to say is not likely to form a two-phase macroscopic solution in distilled water at 25 ° C at a concentration greater than or equal to 1% by weight, or that it has been categorized as hydrophilic in the present application. By anionic or potentially anionic units are meant units which comprise an anionic or potentially anionic group and / or which have been categorized as such. The units or anionic groups are units or groups which have at least one negative charge (generally associated with one or more cations such as cations of alkaline or alkaline earth compounds, for example sodium, or with one or more cationic compounds such as ammonium), regardless of the pH of the medium in which the copolymer is present. The potentially anionic units or groups are units or groups that can be neutral or have at least one negative charge depending on the pH of the medium where the copolymer is present. In this case we will speak of potentially anionic units in neutral form or in anionic form. By extension we can speak of anionic or potentially anionic monomers. Groups considered as anionic are typically strong acid groups, for example pKa less than or equal to 2. Groups considered as potentially anionic are typically weak acid groups, for example pKa greater than 2.

By cationic or potentially cationic units are meant units which comprise a cationic or potentially cationic group, and / or which have been categorized as such. Cationic units or groups are units or groups that have at least one positive charge (usually associated with one or more anions such as chloride ion, bromide ion, sulfate group, methylsulfate group), regardless of pH of the medium in which the copolymer is introduced. The potentially cationic units or groups are units or groups that can be neutral or have at least one positive charge depending on the pH of the medium where the copolymer is introduced. In this case, we will speak of potentially cationic units in neutral form or in cationic form. By extension we can speak of cationic or potentially cationic monomers.

Neutral units are units which do not present a charge, irrespective of the pH of the medium in which the copolymer is present.

In the present application, the ratio by weight between blocks corresponds to the ratio between the masses of the monomers (or mixtures of monomers) used for the preparation of the blocks (taking into account the variations of masses related to a possible subsequent modification). The proportions by weight of the blocks are the proportions relative to the total block copolymer, and correspond to the proportions by weight of the monomers (or mixtures of monomers) used for the preparation of the blocks, with respect to all the monomers used to prepare the copolymer at blocks (taking into account mass variations related to any subsequent modification).

In the present application, the term "transfer agent" is understood to mean an agent capable of inducing a controlled radical polymerization in the presence of unsaturated monomers and possibly of a source of free radicals.

In the present application a "monomer composition" implemented during a polymerization step is defined by the nature and the relative amount of monomers. It can be a single monomer. It may be a combination of several monomers (comonomers), of different natures, in given proportions. Likewise, a composition of a macromolecular chain or a composition of units of a macromolecular chain is defined by the nature and relative amount of the monomers from which the units of the macromolecular chain are derived. It can be a macromolecular chain derived from a single monomer (homopolymeric chain). It may be a macromolecular chain whose units derive from several monomers of different natures, in given proportions (copolymer chain).

In the present application, a different composition of monomers denotes a composition whose nature of the monomer (s) and / or whose proportions in different monomers are different. It is the same by analogy for a different macromolecular chain or a different composition of units. A monomer composition comprising 100% of a monomer M ¹ is different from a composition comprising 100% of an M ² monomer. A monomer composition comprising 50% of a monomer M ¹ and 50% of a monomer A ¹ is different from a composition comprising 10% of the monomer M ¹ and 90% of the monomer A ¹ . A monomer composition comprising 50% of a monomer M ¹ and 50% of a monomer A ¹ is different from a composition comprising 50% of the monomer M ¹ and 50% of a monomer A ² .

In the present application, for simplicity, the units deriving from a monomer are sometimes assimilated to the monomer itself, and vice versa. In the present application, an ethylenically unsaturated monomer is a compound comprising a polymerizable carbon-carbon double bond. It may be a mono-ethylenically unsaturated monomer, preferably an alpha-monoethylenically unsaturated monomer, or a multi-ethylenically unsaturated monomer. In the present application, for compounds different from star copolymers and for different method processes of star copolymer preparations, an ethylenically unsaturated monomer refers to a mono-ethylenically unsaturated monomer, preferably alpha-mono-ethylenically unsaturated monomer. In the present application, the measured average molecular weight of a first block of a first part or of a copolymer denotes the number average molecular mass in terms of polyoxyethylene of a block or a copolymer, measured by chromatography of steric exclusion (SEC), with calibration using polyoxyethylene standards. The measured average molecular weight of a n- ^th block or a n- ^th portion in an n-block or n-part copolymer is defined as the difference between the measured average molecular weight of the copolymer and the measured average molecular weight of the n-1) blocks or parts from which it is prepared.

For the sake of simplicity, it is common to express the average molecular masses of the blocks or parts in "theoretical" average molecular weights or

"targets", from the amounts of monomers and curing agents used, considering a complete and perfectly controlled polymerization. Such calculations can be performed in a conventional manner. For example, a macromolecular chain may be formed by the transfer function of a transfer agent; to obtain the molecular mass it suffices to multiply the average molar mass of the units of a block by the number of units per block (quantity in number of monomers per quantity in number of transfer agent). The theoretical average molecular mass M _b | _0C of a block, is typically calculated according to the following formula:

^M _bl0C precursor where M, is the molar mass of a monomer i, n, is the number of moles of the monomer i, rip _r ecu _r so _r is the number of moles of functions to which will be bound the macromolecular chain of the block. The functions can come from a transfer agent (or a transfer group) or an initiator, a previous block etc. If it is a preceding block, the number of moles can be considered as the number of moles of a compound to which the macromolecular chain of said previous block has been linked, for example a transfer agent (or a group of transfer) or an initiator. In practice, the theoretical average molecular weights are calculated from the number of moles of monomers introduced and the number of moles of introduced precursor.

The "theoretical" or "target" average molecular weight of a block copolymer is considered as the addition of the average molecular weights of each of the blocks. Ampholyte Copolymer

The ampholytic copolymer comprises:

at least one macromolecular chain B comprising cationic B _c units, derived from cationic B _c monomers, and at least one macromolecular chain A linked to a single end of at least one macromolecular chain B.

It is noted that the ampholytic copolymer may comprise one or more part (s) B. It is noted that the ampholytic copolymer may comprise one or more part (s) A. If the copolymer comprises several parts A, may be related to different ends of part B.

The macromolecular chain A is preferably linear (as opposed to a branched and / or star-shaped and / or crosslinked chain). The macromolecular chain B is preferably linear (as opposed to a branched and / or star-shaped and / or crosslinked chain). Advantageously, the two macromolecular chains A and B are linear. The macromolecular chains A and B may be linked together by a carbon-carbon bond, or by another type of bond.

According to a particular embodiment, the copolymer has one or two macromolecular chains B, linked to the macromolecular chain A at one or both of the ends thereof. According to another particular embodiment, the copolymer has one or two macromolecular chains A, linked to the macromolecular chain.

B at one or both ends of it.

The macromolecular chain B can be likened to a "block B" and the macromolecular chain A can be likened to a "block A". The ampholytic copolymer can be referred to as an ampholytic "block copolymer". Preferably, for this variant, the macromolecular chains A and B are linked together by a carbon-carbon bond. The copolymer is preferably a block copolymer, preferably linear, comprising at least one block A and at least one block B, where the macromolecular chain A constitutes block A and the macromolecular chain B constitutes block B.

The ampholytic copolymer may in particular be chosen from the following copolymers:

- diblock copolymer (block A) - (block B), the part A constituting the block A and the macromolecular chain B constituting the block B,

triblock copolymer (block B) - (block A) - (block B), part A constituting block A and the macromolecular chain B constituting block B, triblock copolymer (block A) - (block B) - (block A), part A constituting block A and the macromolecular chain B constituting block B.

According to a preferred embodiment, the copolymer is a linear diblock or triblock copolymer whose block A and / or block B, preferably both, is derived from ethylenically unsaturated monomers, preferably mono-alpha-ethylenically unsaturated monomers and / or or di-allylic cyclopolymerizable type (such as N, N-dimethyldiallylammonium chloride "DADMAC").

The units A _A comprise an anionic or potentially anionic group chosen from the following groups, in acid or salified form:

the carboxylate group -COO ^"

the sulphonate group -SO ₃ ^"

the sulfate group -SO ₄ ^" -the phosphonate group -PO ₃ ^2"

the phosphate group -PO ₄ ^{2 "} .

Groups considered as anionic are typically strong acid groups, for example pKa less than or equal to 2. Groups considered as potentially anionic are typically weak acid groups, for example pKa greater than 2.

Units A _A are different from units derived from styrene sulfonate in acid or salt form. It is mentioned, however, that the copolymer may comprise units derived from styrene sulphonate (anionic units) associated with other units as defined above. Preferably, the copolymer does not comprise units derived from styrene sulphonate. According to a particular embodiment, the anionic or potentially anionic group is different from a sulphonate group.

If the group is in acid form, it is associated with at least one or more protons. The group may be associated with a counterion (a cation) different from a proton. It may especially be a cation of an alkali metal or alkaline earth metal, in particular the sodium or potassium ion, or an organic cation, for example an ammonium ion. It is noted that the cationic groups of part B may constitute all or part of the counter ions associated with the anionic or potentially anionic group. It is mentioned that the anionic or potentially anionic groups are not zwitterionic groups comprising both a cationic group and an anionic or potentially anionic group (they would then be of generally zero charge). The units B _c are the cationic units. They include cationic groups, including a quaternary ammonium group. In the present application, the cationic groups do not cover cationic groups, of weak base type, which may become cationic by adding a proton such as primary amines, or secondary amines, or even as amide groups. The cationic groups can in particular be groups of type:

quaternary ammonium (of formula -N ⁺ R _{3 in} which R, identical or different, is a group other than the hydrogen atom, for example a hydrocarbon-based group, optionally substituted, optionally interrupted by heteroatoms, for example a linear or branched C ₁ -C ₂₂ alkyl group, for example a methyl group).

It is not excluded to associate quaternary ammonium groups with cationic groups of:

- Inium (of formula = N ⁺ R ₂ where R, identical or different, is a group different from the hydrogen atom, one of which is optionally part of a cycle connected to the double bond, said ring optionally being aromatic, at least one of the groups R possibly being, for example, an optionally substituted hydrocarbon-based group, optionally interrupted by heteroatoms, for example a linear or branched C ₁ -C ₂₂ alkyl group, for example a group methyl).

In the case of quaternary ammonium groups, it may in particular be a trimethylammonium group.

In the case of inium groups, it may especially be a pyridinium group, preferably an alkylpyridinium group, preferably a methylpyridinium group.

The cationic group may be associated with a counter ion (anion). It may especially be a chloride, bromide, iodide, nitrate, methylsulfate or ethylsulfate ion. It is noted that the anionic or potentially anionic groups of part A may constitute all or part of the counter ions associated with the cationic group. It is mentioned that the cationic units are not zwitterionic units comprising both a cationic group and an anionic or potentially anionic group (they would then be of generally zero charge). In other words, the R groups mentioned below do not include an anionic substituent.

The net charge of the copolymer may in particular be positive at at least a pH greater than or equal to 4.5, preferably to 7.

By way of examples of monomers B _{c from} which the units B _c can be derived, mention may be made of:

trimethylammoniumpropylmethacrylate chloride, trimethylammoniumethylacrylamide chloride or bromide or methacrylamide,

trimethylammoniumbutylacrylamide methylsulfate or methacrylamide,

trimethylammoniumpropylmethacrylamide methylsulfate (MAPTA MeS),

- (3-methacrylamidopropyl) trimethylammonium chloride (MAPTAC), - (3-acrylamidopropyl) trimethylammonium chloride (APTAC),

methacryloyloxyethyltrimethylammonium chloride or methylsulfate,

acryloyloxyethyltrimethylammonium salts (ADAMQUAT),

N, N-dimethyldiallylammonium chloride (DADMAC);

dimethylaminopropylmethacrylamide chloride, N- (3-chloro-2-hydroxypropyl) trimethylammonium (DIQUAT);

the monomer of formula

where X ^" is an anion, preferably chloride or methylsulfate, - their mixtures or combinations.

As examples of monomers from which can be derived units comprising an inium-type group, there may be mentioned bromide, chloride or methylsulfate of 1-ethyl-2-vinylpyridinium, 1-ethyl-4-vinylpyridinium.

The units B _c may in particular be obtained by polymerization, in order to form at least one macromolecular chain B, of monomers comprising the monomers B _c (optionally mixed with other monomers). They can also be obtained by polymerization, in order to form at least one _pre- cursor precursor B macromolecular chain, monomers comprising precursor monomers of units B _c (optionally mixed with other monomers), leading to precursor units of units B _c , then chemical modification of the precursor units to obtain the units B _c in a macromolecular chain B. Such modifications are known. It may for example be quaternizations, for example using quaternary dimethyl sulphate or haloalkylammonium or quaternary haloalkylhydroxyalkylammonium.

The macromolecular chain B may comprise other units B _other than units B _c , not comprising a cationic group, derived from monomers B _at t _re , different from the monomers B _c , not comprising a cationic group. It can include:

hydrophilic neutral units N _phl ie derived from hydrophilic neutral monomers N _phl ι _e ,

hydrophobic neutral units N _phO be derived from hydrophobic neutral N _phO be monomers

- of anionic or potentially anionic units B _A, deriving from anionic monomers B _A or potentially anionic

zwitterionic Z units, derived from zwitterionic Z monomers,

potentially cationic C units derived from potentially cationic monomers.

- their mixtures or association.

The proportion by weight of units B _in t _re in the macromolecular chain B can be from 0 to 99%, preferably from 0 to 90%, preferably from 0 to 50%, eg 0 to

25%. It can advantageously be zero (no units B _at t _re ). The macromolecular chain B preferably comprises from 1 to 100%, by weight, of units _Bc , preferably from 50% to 100%.

In the case where a macromolecular chain B comprises units B _A , their proportion by number in said chain is preferably lower than that in the macromolecular chain A if such a chain is present. Preferably the proportion by number of units B _A in a macromolecular chain B is less than the proportion by number of units B _c . Preferably the proportion by number of units B _A in a macromolecular chain B is less than 10%, preferably zero.

By way of examples of monomers C, from which C units may be derived, mention may be made of:

N, N-dimethylaminomethyl-acrylamide or methacrylamide,

2 (N, N-dimethylamino) ethyl-acrylamide or methacrylamide,

3 (N, N-dimethylamino) propyl-acrylamide or -methacrylamide, 4 (N, N-dimethylamino) butyl-acrylamide or -methacrylamide

2 (dimethylamino) ethyl acrylate (ADAM),

2 (dimethylamino) ethyl methacrylate (DMAM or MADAM),

3 (dimethylamino) propyl methacrylate, 2 (tert-butylamino) ethyl methacrylate,

- 2 (dipentylamino) ethyl methacrylate, - 2 (diethylamino) ethyl methacrylate

vinylpyridines

- the amino vinyl vinylimidazolines.

Examples of monomers N _phl ι _e which may derived units N _ph ιie, there may be mentioned: - the hydroxyalkyl esters of ethylenically unsaturated α-β acids, such as acrylates and methacrylates, hydroxyethyl, hydroxypropyl, glycerol monomethacrylate ...

α-β ethylenically unsaturated amides, such as acrylamide, methacrylamide, N, N-dimethyl methacrylamide, N-methylolacrylamide, etc.

α-β ethylenically unsaturated monomers bearing a water-soluble polyoxyalkylene segment of the polyethylene oxide type, such as ethylene polyoxide α-methacrylates (BISOMER S20W, S10W, ... from LAPORTE) or α, ω-dimethacrylates, SIPOMER RHODIA BEM (polyoxyethylene ω-behenyl methacrylate), SIPOMER SEM-25 from RHODIA (polyoxyethylene ω-tristyrylphenyl methacrylate) ...

vinyl alcohol; α-β ethylenically unsaturated monomers precursors of hydrophilic units or segments such as vinyl acetate which, once polymerized, can be hydrolysed to generate vinyl alcohol units or polyvinyl alcohol segments;

vinyl-lactams, such as vinylpyrrolidones, or N-vinylcaprolactam, α-β-ethylenically unsaturated monomers of ureido type and in particular methacrylamido of 2-imidazolidinone ethyl (Sipomer WAM II from Rhodia);

nonethylene glycol methyl ether acrylate or nonethylene glycol methyl ether methacrylate

- their mixtures or associations.

As examples of monomers which may N _phobic derived units N _phobic, there may be mentioned:

vinylaromatic monomers such as styrene, alpha-methylstyrene, vinyltoluene, etc.

vinyl or vinylidene halides, such as vinyl chloride, vinylidene chloride, aromatic vinyl halides such as styrene pentafluoride

the C ₁ -C ₁₂ alkyl esters of α-β monoethylenically unsaturated acids, such as the methyl, ethyl, butyl acrylates and methacrylates, and 2-ethylhexyl acrylate, etc.

vinyl or allyl esters of saturated carboxylic acids such as acetates, propionates, versatates, stearates ... of vinyl or of allyl

the α-β monoethylenically unsaturated nitriles containing from 3 to 12 carbon atoms, such as acrylonitrile, methacrylonitrile, etc. α-olefins such as ethylene ...

conjugated dienes, such as butadiene, isoprene, chloroprene,

monomers capable of generating polydimethylsiloxane (PDMS) chains. Thus part B may be a silicone, for example a polydimethylsiloxane chain or a copolymer comprising dimethylsiloxy units,

diethyleneglycolethyletheracrylate or diethyleneglycolethylethermethacrylate

- their mixtures or associations.

By way of examples of zwitterionic monomers Z from which zwitterionic units Z may be derived, mention may be made of:

monomers carrying a carboxybetaine group,

monomers bearing a sulphobetaine group, for example sulphopropyl dimethyl ammonium ethyl methacrylate (SPE), sulphoethyl dimethyl ammonium ethyl methacrylate, sulphobutyl dimethyl ammonium ethyl methacrylate, sulphohydroxypropyl dimethyl ammonium ethyl methacrylate (SHPE), sulphopropyl dimethylammonium propyl acrylamide, sulfopropyl dimethylammonium propyl methacrylamide (SPP), sulfohydroxypropyl dimethyl ammonium propyl methacrylamido (SHPP), sulfopropyl diethyl ammonium ethyl methacrylate, or sulfohydroxypropyl diethyl ammonium ethyl methacrylate, monomers carrying a phosphobetaines group, such as phosphatoethyl trimethylammonium ethyl methacrylate.

- their mixtures or associations.

Examples of monomers _BA which can be derived from units B _A, there can be mentioned monomers _A detailed below.

The macromolecular chain A of the second embodiment comprises anionic or potentially anionic A _A units derived from A _A monomers.

As examples of monomers A _{A from} which the units A _A can be derived, mention may be made of:

monomers possessing at least one carboxylic function, such as the α-β ethylenically unsaturated carboxylic acids or the corresponding anhydrides, such as acrylic, methacrylic, maleic, fumaric acid, itaconic acid or N-methacryl acid or anhydrides; alanine, N-acryloylglycine, paracarboxystyrene, and their water-soluble salts monomers precursors of carboxylate functions, such as tert-butyl acrylate, which generate, after polymerization, carboxylic functions by hydrolysis,

monomers having at least one sulphate or sulphonate function, such as 2-sulphooxyethyl methacrylate, vinylbenzene sulphonic acid, allyl sulphonic acid, 2-acrylamido-2-methylpropanesulphonic acid, sulphoethyl acrylate or methacrylate, acrylate or sulfopropyl methacrylate and their water-soluble salts

monomers having at least one phosphonate or phosphate function, such as vinylphosphonic acid, esters of ethylenically unsaturated phosphates such as phosphates derived from hydroxyethyl methacrylate (Empicryl 6835 from Rhodia) and those derived from polyoxyalkylene methacrylates; and their water-soluble salts,

- their mixtures or associations.

As examples of monomers comprising a phosphate or phosphonate function, mention is made in particular of:

the N-methacrylamidomethylphosphonic acid ester derivatives, in particular the n-propyl ester (RN 31857-1 1-1), the methyl ester (RN 31857-12-2), the ethyl ester (RN 31857-13-3), n-butyl ester (RN 31857-14-4), isopropyl ester (RN 51239-00-0), and their monoacid and di-phosphonic acid derivatives, such as N-methacrylamidomethylphosphonic acid diacid (RN 109421-20-7),

the N-methacrylamidoethylphosphonic acid ester derivatives, such as the N-methacrylamidoethylphosphonic acid dimethyl ester (RN 266356-40-5), the di (2-butyl-3,3-dimethyl) ester of the N-methacrylamidoethylphosphonic acid (RN 266356-45-0), and their monoacid and di-phosphonic acid derivatives, such as N-methacrylamidoethylphosphonic acid dihydrate (RN 80730-17-2),

derivatives of N-acrylamidomethylphosphonic acid esters, such as N-acrylamidomethylphosphonic acid dimethyl ester (RN 24610-95-5), N-acrylamidomethylphosphonic acid diethyl ester (RN 24610-96- 6), bis (2-chloropropyl) N-acrylamidomethyl phosphonate (RN 50283-36-8), and their monoacid and phosphonic acid derivatives such as N-acrylamidomethylphosphonic acid (RN 151752-38-4),

dialkyl ester vinylbenzylphosphonate derivatives, in particular derivatives di (n-propyl) (RN 60181-26-2), di (isopropyl) (RN 159358-34-6), diethyl (RN 726-61-4), dimethyl (NR 266356-24-5), di (2-butyl-3,3-dimethyl) (RN 266356-29-0) and di (t-butyl) ester (RN 159358-33-5), and their variants monoacid and phosphonic acid, such as vinylbenzylphosphonic diacid (RN 53459-43-1), diethyl 2- (4-vinylphenyl) ethanephosphonate (RN 61737-88-0), dialkylphosphonoalkyl acrylate and methacrylate derivatives, such as 2- (acryloyloxy) ethylphosphonic acid dimethyl ester (RN 54731-78-1) and 2- (methacryloyloxy) ethylphosphonic acid dimethyl ester (RN 22432-83- 3), 2- (methacryloyloxy) methylphosphonic acid diethyl ester (RN 60161-88-8), racide2- (methacryloyloxy) methylphosphonic dimethyl ester (RN 63411-25-6), dimethyl ester of 2- (methacryloyloxy) propylphosphonic acid (RN 252210-28-9), 2- (acryloyloxy) methylphosphonic acid diisopropyl ester (RN 51238-98-3), 2- (acryloyloxy) ethylphosphonic acid diethyl ester (RN 20903-86-0), and their monoacid and phosphonic acid variants, such as 2- (methacryloyloxy) ethylphosphonic acid (RN 80730-17-2), 2- (methacryloyloxy) methylphosphonic acid (RN 87243-97- 8), 2- (methacryloyloxy) propylphosphonic acid (RN 252210-30-3), 2- (acryloyloxy) propylphosphonic acid (RN 254103-47-4) and 2- (acr yloyloxy) ethylphosphonic acid - vinyl phosphonic acid, optionally substituted by cyano, phenyl, ester or acetate groups, vinylidene phosphonic acid, in the form of a sodium salt or its isopropyl ester, bis (2-chloroethyl) vinylphosphonate

2- (methacryloyloxy) ethyl phosphate,

2- (acryloyloxy) ethyl phosphate, 2- (methacryloyloxy) propyl phosphate,

2- (acryloyloxy) propyl phosphate, and

vinyl phosphonic acid,

2- (methacryloyloxy) ethyl phosphonic acid,

2- (acryloyloxy) ethyl phosphonic acid, 2- (methacryloyloxy) ethyl phosphate, and

2- (acryloyloxy) ethyl phosphate.

The A _A units can in particular be obtained by polymerization, in order to form the macromolecular chain A, of monomers comprising the monomers A _A (optionally mixed with other monomers). It can also be obtained by polymerization, in order to form at least one precursor precursor macromolecular chain, of monomers comprising precursor monomers of A _A units (optionally mixed with other monomers), leading to precursor units of the A units. _A , and then chemical modification of the precursor units in order to obtain the A _A units in the macromolecular chain A. Such modifications are known. It may for example be hydrolyses of units comprising an ester group hydrolyzable (units derived from acrylate or ethyl methacrylate or tert-butyl for example).

The macromolecular chain may comprise units A _OTH ER, different units A _A, not including anionic or potentially anionic group, deriving from monomers _{_A} other, different from monomers _A, not comprising anionic group or potentially anionic. It can include:

hydrophilic neutral units N _phl ie, deriving from hydrophilic neutral N monomers N _phl ι _e (of such units and monomers are described above), from hydrophobic _neutrophilic units N _phO be derived from N _phO be neutral monomers hydrophobic (such units and monomers are described above)

cationic units A _c , derived from cationic monomers A _c ,

zwitterionic Z units, derived from zwitterionic Z monomers (such units and monomers are described above), from potentially cationic C units derived from potentially cationic monomers (such units and monomers are described above),

- their mixtures or association.

The proportion by weight of units _{_A} other in the macromolecular chain A may be 0 to 99%, preferably from 0 to 90%, preferably from 0 to 50%, eg 0 to

25%. It can advantageously be zero (no A units _at t _re ). The macromolecular chain A preferably comprises from 1 to 100%, by weight, of A _A units, preferably from 50% to 100%.

In the case where a macromolecular chain A comprises A _c units, their proportion by number in said chain is preferably lower than that in the macromolecular chain B. Preferably the proportion by number of A _c units in a macromolecular chain A is less than the proportion by number of units A _A. Preferably the proportion by number of A _c units in a macromolecular chain A is less than 10%, preferably zero.

As examples of monomers which may be derived _c units A _C, there may be mentioned the monomers B _c detailed above.

By way of example also, the ampholytic copolymer may be a block copolymer in which block A is derived from acrylic acid and block B is derived from a cationic monomer chosen from DADMAC, MAPTAC and APTAC. The ampholytic copolymer preferably comprises more, in number, of units B _c than of anionic or potentially anionic A _A units. Preferably it comprises more in number of units B _c than A _A units.

Preferably, the ratio by weight of the macromolecular chain (s) B, preferably the block (s) B, and the macromolecular chain (s) A, preferably the the block (s) A is greater than 1, for example greater than 2. The weight ratio between the macromolecular chain A and the portion B may alternatively be greater than 1, preferably greater than 2.

The ampholytic copolymer may in particular have a theoretical or measured average molecular mass of between 500 and 50000 g / mol. The at least one macromolecular chain (s) B, preferably at least one block (s) B, can in particular have a theoretical or measured average molecular weight of between 500 and 49000 g / mol, preferably between 2000 and 48000 g. / mol. The at least one macromolecular chain (s) A, preferably at least one block (s) A, may in particular have a theoretical or measured average molecular mass of between 250 and 20000 g / mol, preferably between 500 and 10000 g. / mol.

The ampholytic copolymer is preferably water-soluble, and preferably water-soluble over the entire pH range of from 5 to 8, preferably from 4 to 9, preferably from 1 to 1. The nature and proportions of the various units may be chosen for this purpose. Preferably it comprises less than 50% by weight of units N _phO be, preferably less than 25%, preferably less than 10%, for example not at all.

The copolymer may be in solid form or in the form of a solution, for example an aqueous, alcoholic and / or aqueous-alcoholic solution (for example in an ethanol or isopropanol / water mixture). The concentration of the solution may for example be from 5 to 75% by weight, typically from 10 to 50%.

Processes useful for the preparation of the ampholytic copolymers

The ampholytic copolymer can be prepared by any suitable method, including sequential polymerizations. Such methods are known. In particular, the copolymer can be prepared by sequential polymerizations, preferably of controlled radical polymerization type.

In particular, it is possible to implement a process comprising the following steps to prepare block copolymers: step 1): polymerization, preferably by controlled radical polymerization, of monomers so as to obtain a first block chosen from block A and block B , or a precursor block of the first block, step 2): polymerization, preferably by controlled radical polymerization, of monomers so as to obtain at least a second block chosen from block A if a block B or a precursor was obtained in step 1, and block B if a block A or a precursor was obtained in step 1), or a precursor block of the second block, step 3) optional: if precursor blocks were obtained during steps 1) and / or 2), chemical modification of these blocks so as to obtain block A and block B.

Block B is preferably prepared by polymerization of monomers comprising cationic B _c monomers. Block A is preferably prepared by polymerizing monomers comprising potentially anionic monomers A _A.

Steps 1) and 2) are sequential. It is not excluded to perform other polymerization steps before step 3). Block B can be prepared in step 1) and then block A in step 2), and possibly another block B in a subsequent step. However, it is preferred to prepare block A in step 1) and then at least one block B in step 2). In all cases, it is preferred to operate step 2) on a block from step 1) carrying no load. For this purpose, if the block B is prepared in step 2), in particular if it is operated directly using monomers B _c (without subsequent chemical modification), it is preferably carried out at a pH such that the units A _A are in a neutral form, preferably in an acidic medium, for example at a pH of less than or equal to 4, preferably 3, for example 2. However, if block A is prepared in step 2), then it may be preferable to prepare a precursor of block B during step 1), nonionic or potentially cationic in neutral form, and then chemically modify it in a step 3). If the monomer B _c is diallyl ammonium type, it is preferred to polymerize it in step 2).

Chemical modifications that can be carried out in the context of step 3) have been described above: for example, quaternizations to obtain the hydrolysis block B to obtain block A. Preferably, no one operates. no step 3) of chemical modification, directly polymerizing monomers B _c in one of steps 1) or 2) and the monomers A _A in the other step.

The method may in particular comprise a step of deactivating transfer groups carried by macromolecular chains, and / or purification of the copolymer and / or destruction of chemical modification and / or deactivation by-products. Such a step can be performed after the polymerization steps. It can be operated before or after step 3) if it is implemented. During the purification and / or deactivation and / or optional destruction step, the block copolymers obtained or the by-products can undergo a purification or destruction reaction of certain species, for example by hydrolysis, oxidation, reduction, pyrolysis, ozonolysis or substitution type processes. An oxidation step with hydrogen peroxide is particularly suitable for treating sulfur species. It is mentioned that some of these reactions or operations may take place in whole or in part during step 3). In this case, for these reactions or operations, the two steps are simultaneous.

Preferably, for the polymerization steps (steps 1) and 2) in particular), it is implemented so-called living or controlled radical polymerization methods, and particularly preferably controlled or living radical polymerization methods implementing a transfer agent comprising a transfer group of formula -S-CS-, especially known under the names of RAFT or MADIX. By way of examples of so-called living or controlled polymerization processes, mention may in particular be made of:

the processes of the applications WO 98/58974, WO 00/75207 and WO 01/42312 which implement controlled radical polymerization by xanthate control agents; and the radical polymerization process controlled by control agents of the type dithioesters or trithiocarbonates of the application WO 98/01478,

to the radical polymerization process controlled by dithiocarbamate type control agents of the application WO 99/31144, the radical polymerization process controlled by dithiocarbazate type control agents of the application WO 02/26836,

to the radical polymerization process controlled by dithiophosphoroester type control agents of the application WO 02/10223,

the process of the application WO 99/03894 which implements a polymerization in the presence of nitroxide precursors, or the processes implementing other nitroxides or nitroxide / alkoxyamine complexes

the process of the application WO 96/30421 which uses a radical polymerization by atom transfer (ATRP),

to the radical polymerization process controlled by iniferter type control agents according to the teaching of Otu et al., Makromol. Chem. Rapid. Commun., 3, 127 (1982), to the radical polymerization process controlled by degenerative iodine transfer according to the teaching of Tatemoto et al., Jap. 50, 127, 991 (1975), Daikin Kogyo Co. Itd Japan and Matyjaszewski et al., Macromolecules, 28, 2093 (1995),

to the radical polymerization process controlled by tetraphenylethane derivatives, disclosed by D. Braun et al. In Macromol. Symp. 11, 63 (1996), or again,

to the radical polymerization process controlled by organocobalt complexes described by Wayland et al. In J.Am.Chem.Soc. 116.7973 (1994)

- The radical polymerization process controlled by diphenylethylene (WO 00/39169 or WO 00/37507).

Steps 1) and 2) can typically be carried out by bringing into contact with the monomers, a control agent, and optionally at least one source of free radicals. The source of free radicals can be an initiator. Such an initiator is preferably used in step 1). An initiator can be introduced again in step 2). It is also possible to use free radicals present in the reaction medium resulting from stage 1).

The polymerizations may be carried out in the presence of free radical initiators, known to those skilled in the art. For example, sodium persulfate may be used. Initiator quantities of 5 to 50% by number relative to the amount of transfer agent can typically be used.

The polymerizations are advantageously carried out in solution, preferably in aqueous, alcoholic or hydro-alcoholic medium.

Transfer agents useful for the implementation of the method (in steps 1) and 2)) are known to those skilled in the art and include in particular compounds comprising a transfer group -S-CS-, for the implementation of polymerization processes known as RAFT and / or MADIX. A transfer agent comprising a transfer group of the formula -S-CS-O- (Xanthate) is preferably used. Such methods and agents are detailed below. During the polymerization steps, it is possible to prepare a first block from monomers or from a mixture of monomers, initiators and / or agents promoting the control of the polymerization (group transfer agents). S-CS-, nitroxides, etc.), then the growth of a second block on the first block to obtain a diblock copolymer with monomer compositions different from those used for the preparation of the preceding block (in particular with different monomers), and optionally with addition of initiators and / or agents promoting the control of the polymerization. These processes for the preparation of block copolymers are known of the skilled person. It is mentioned that the copolymer may have at the chain end or in the center of the chains a transfer group or a residue of a transfer group, for example a group comprising a group -S-CS- (for example derived from a Xanthate , a dithioester, a dithiocarbamate or a trithiocarbonate) or a residue of such a group.

It is mentioned that one would not depart from the scope of the invention by implementing and adapting methods of preparation leading to triblock copolymers optionally modified subsequently (for example during a specific step or when a step of destruction and / or deactivation and / or purificatoin) so as to obtain diblock copolymers. In particular it is conceivable to use transfer agents comprising several transfer groups (for example trithiocarbonates ZS-CS-SZ) leading to telechelic copolymers of type R - [(block B) - (block A)] _w as triblock type (core) - [(block A) - (block B)] _x (for example (block A) - (block B) -R- (block B) - (block A) as triblocks (block A - (block B) - (core) - (block B) - (block A)), then break at the core (section, "cleave") the telechelic copolymers, to obtain diblock copolymers (block A) - (block B). The section may intervene during hydrolysis. In such cases, those skilled in the art will adapt the operating conditions to target average molecular weights equivalent to those indicated, for example by multiplying the amounts of monomers introduced by the number of transfer groups included in the agent of the invention. transfer.

uses

The copolymers may especially be used in compositions, for example aqueous, comprising a product dispersed or solubilized in the composition. The product is typically a different product of the copolymer, the latter being preferably an additive. The copolymer may especially be used, preferably in aqueous compositions, to stabilize a dispersed product and / or to control a stabilization or destabilization of a product under the impact of a change applied to the composition, such as the addition of a compound, dilution and / or pH change, or as a change in temperature. It can be used as a controlled release agent for assets.

As aqueous compositions in which the copolymer can be used, mention is made in particular of:

phytosanitary compositions, inks,

- pigment compositions cosmetic compositions, especially compositions intended to be rinsed, or compositions intended to be left on the skin, for example sunscreen products

- water treatment compositions - household care compositions, for example, detergents or hard surface cleaning compositions or laundry cleaning or rinsing compositions or dishwashing or cleaning compositions, in accordance with the present invention. machine or by hand,

plastics treatment compositions, coating compositions, or pretreatment compositions,

fluid compositions used in the exploitation of oil and / or gas deposits,

aqueous lubricants,

pharmaceutical compositions.

Other details or advantages of the invention may appear in light of the examples which follow without limitation.

EXAMPLES The characterization of the relative molar masses of neutral or anionic hydrophilic polymers (eg poly (acrylic acid) homopolymers and poly (acrylamide)) is carried out by size exclusion chromatography (CES) using a Shodex OH pak SB-G precolumn ( No. L410061) and three Shodex columns of 30 cm OH pak SB-806M HQ (No. L 41 1054; L 41 1055; L 41 1056) and a mobile phase containing acetonitrile in a deionized water solution. additive with 0.1 mol / L of NaNO3, the ratio by volume acetonitrile / water is 20/80. The characterizations of the relative molar masses of the copolymers containing a cationic block is carried out by size exclusion chromatography (CES) using a Shodex OH pak SB-G precolumn (No. L211067) and three Shodex columns of 30 cm. 806M HQ (No. L 30101 1; L 301013; L 301014) and a mobile phase containing acetonitrile in a permutated water solution additive with 1 mol / L NH ₄ NO ₃ and 100 ppm of DADMAC (so as to passivate columns), the volume ratio acetonitrile / water is 20/80. All relative molar mass measurements are made relative to poly (ethylene oxide) standards. In the examples, the water used is permutated water. EXAMPLE 1 Synthesis of a diblock copolymer poly (acrylic acid) [500] -block-poly (diallyldimethylammonium chloride) [3000]

The values in square brackets correspond to the theoretical average molar masses for each block.

Example 1.1. Synthesis of the acrylic polyfacid block)

In a 2 L jacketed glass reactor equipped with mechanical stirring and a cooling column, 31.87 g of O-ethyl-S- (1-methoxycarbonyl) ethyl) xanthate (CH ₃ CHCO ₂ CH ₃ ) S (C = S) OEt, 101.3 g of ethanol, 8.5 g of acrylic acid and 23.64 g of deionized water are introduced at room temperature. The temperature of the solution is increased to 70 ^° C. As soon as this temperature has been reached, 0.49 g of 4,4'-azobis (cyanovaleric) acid are introduced. Upon introduction of this initiator, a solution of 76.5 g of acrylic acid in 212.8 g of water is introduced for one hour. At the end of the introduction, 0.49 g of 4,4'-azobis (cyanovaleric) acid are again introduced. The reaction is prolonged for three hours after the end of the introduction.

A polymer sample is taken. The analysis of the product by high performance liquid chromatography (HPLC) makes it possible to conclude that all the acrylic acid has reacted during the polymerization. An analysis by size exclusion chromatography (CES) with a relative calibration of poly (ethylene oxide) gives the following average molecular weight (M _n ) and polymolecularity index (M _w / M _n ) values. M _n = 650 g / mole, M _w / M _n = 1.60.

Example 1.2. Obtaining the diblock copolymer

At the end of synthesis of the first block, as described in Example 1.1, the temperature is decreased to 65 ° C. Once this temperature has stabilized, a solution of 706 g of diallyl dimethyl ammonium chloride (DADMAC) at 65% by weight in water and 4 g of V50 initiator sold by the company Wako (2,2'-azobis (2-methylproprionamidine) dihydrochloride) are introduced. The reaction is then maintained at this temperature for twelve hours. After 4 hours and 8 hours of reaction, 4 g of V50 initiator are added each time to the reaction medium. At the end of the reaction, a sample is taken. ¹ H NMR analysis gives a conversion to DADMAC equal to 98.2%. Mn and Mw / Mn are measured by CES in water with a poly (ethylene oxide) calibration curve: M _n = 2500; M _w / M _n = 1.50. The superposition of the two chromatograms of the products of the example 1.1 and example 1.2 allows to conclude the diblock nature of the copolymer formed. Indeed, the chromatogram CES of the product of Example 1.1 is totally displaced towards the highest molecular weight range at the end of the synthesis of the product of Example 1.2.

The diblock copolymer is soluble in water (especially at 2% by weight). It makes it possible to stabilize (with a quantity of 1% by weight) a colloidal mineral suspension over a pH range from 3 to 10. By way of comparison, the same colloidal suspension is not stable (flocculation) at a higher pH. at 3 in the absence of the copolymer, or in the presence of a neutral block-cationic diblock copolymer comprising a block of acrylamide of theoretical molecular weight of 500 g / mol, and a block deriving from mass APTAC. theoretical molar of 3000 g / mol.

Example 2 Synthesis of a diblock copolymer poly (acrylic acid) [1000] -block-poly (3-acrylamidopropyltrimethylammonium "APTAC") [3000]

Example 2.1. Synthesis of the poly (acrylic acid) block

In a 250 mL jacketed glass reactor equipped with magnetic stirring and a cooling column, 6.2 g of O-ethyl-S- (1-methoxycarbonyl) ethyl) xanthate (CH ₃ CHCO ₂ CH ₃ ) S (C = S) OEt, 23.7 g of ethanol, 30 g of acrylic acid and 74.9 g of permutated water are introduced at ambient temperature and subjected to nitrogen reflux for 5 min. The temperature of the solution is increased to 70 ^° C. As soon as this temperature has been reached, 0.167 g of 4,4'-azobis (cyanovaleric) acid is introduced. After three hours of reflux, 0.167 g of 4,4'-azobis (cyanovaleric) acid is again introduced. The reaction is continued for another four hours with magnetic stirring. A polymer sample is taken. The analysis of the product by high performance liquid chromatography (HPLC) makes it possible to conclude that all the acrylic acid has reacted during the polymerization. An analysis by size exclusion chromatography (CES) with a relative calibration of poly (ethylene oxide) gives the following average molecular weight (M _n ) and polymolecularity index (M _w / M _n ) values. M _n = 960 g / mol, M _w / M _n = 1.70.

Example 2.2. Obtaining the diblock copolymer At the end of the synthesis of the first block, as described in Example 2.1, the temperature is decreased to 65 ° C. Once this temperature has stabilized, a solution of 15.7 g of 3-acrylamidopropyltrimethylammonium chloride (APTAC) at 75% by weight in water, 0.073 g of initiator V50 (2,2'-azobis (2-methylproprionamidine) dihydrochloride) and 10 g of deionized water, previously degassed by a stream of nitrogen (5min), are introduced into the solution of the first block. The reaction is then maintained at this temperature (65 ° C.) for 9h30 with magnetic stirring. After 4 hours of reaction, 0.073 g of V50 initiator is added to the reaction medium. At the end of the reaction, a sample is taken. ¹ H NMR analysis gives an APTAC conversion of 99%. Mn and Mw / Mn are measured by CES, after calibration with poly (ethylene oxide) give: M _n = 2740 g / mol; M _w / M _n = 1.50. The superposition of the two chromatograms of the products of Example 2.1 and Example 2.2 makes it possible to conclude the diblock nature of the copolymer formed. Indeed, the chromatogram CES of the product of Example 3 is totally displaced towards the field of the highest molecular weights at the end of the synthesis of the product of Example 2.2.

The diblock copolymer is soluble in water (especially at 2% by weight).

It makes it possible to stabilize (with a quantity of 1% by weight) a colloidal mineral suspension over a pH range from 3 to 10. By way of comparison, the same colloidal suspension is not stable (flocculation) at a higher pH. at 3 in the absence of the copolymer, or in the presence of a diblock copolymer comprising a neutral-block-cationic type comprising a block derived from acrylamide of theoretical molecular weight of 500 g / mol, and a block deriving from APTAC of theoretical molar mass of 3000 g / mol.

Claims

An ampholytic copolymer comprising at least one macromolecular chain B and at least one part A linked to one end of the macromolecular chain B, in which: the macromolecular chain B comprises cationic units B _c , derived from cationic monomers B _c ,

Part A is a macromolecular chain A comprising potentially anionic A _A units, derived from potentially anionic monomers A _A , characterized in that: the units B _c comprise a quaternary ammonium group, and

the units A _A comprise a group chosen from the following groups, in acid or salified form:

the carboxylate group -COO ^"

the sulphonate group -SO ₃ ^" the sulphate group -SO ₄ ^"

the phosphonate group -PO ₃ ^{2 "}

2. Copolymer according to the preceding claim, characterized in that the net charge of the copolymer is positive at at least a pH greater than or equal to 4.5, preferably to 7.

3. Copolymer according to one of the preceding claims, characterized in that it comprises more in number of units B _c than A _A units.

4. Copolymer according to one of claims 1 to 3, characterized in that the copolymer is a block copolymer, preferably linear, comprising at least one block A and at least one block B, where the macromolecular chain A constitutes the block. A and the macromolecular chain B constitutes the block B.

5. Copolymer according to one of the preceding claims, characterized in that the copolymer is among the following copolymers:

triblock copolymer (block B) - (block A) - (block B), part A constituting block A and the macromolecular chain B constituting block B, triblock copolymer (block A) - (block B) - (block A).

6. Copolymer according to claim 5, characterized in that the copolymer is a linear diblock or triblock copolymer whose block A and block B are derived from ethylenically unsaturated monomers.

7. Copolymer according to one of the preceding claims, characterized in that the units B _c are cationic units selected from units derived from the following cationic monomers: - trimethylammoniumpropylmethacrylate chloride,

trimethylammoniumethylacrylamide chloride or bromide or methacrylamide,

trimethylammoniumbutylacrylamide methylsulfate or methacrylamide,

trimethylammoniumpropylmethacrylamide methylsulfate (MAPTA MeS),

methacryloyloxyethyltrimethylammonium chloride or methylsulfate,

acryloyloxyethyltrimethylammonium salts (ADAMQUAT),

1-ethyl-2-vinylpyridinium bromide, chloride or methylsulfate, of 1-ethyl-4-vinylpyridinium; N, N-dimethyldiallylammonium chloride (DADMAC);

the monomer of formula

where X ^" is an anion, preferably chloride or methylsulfate

- their mixtures or associations.

8. Copolymer according to one of claims 1 to 7, characterized in that the A _A units are potentially anionic units selected from the units derived from the following potentially anionic monomers A _A :

Acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, N-methacrylalanine, N-acryloylglycine and their water-soluble salts,

Vinylphosphonic acid, esters of ethylenically unsaturated phosphates.

9. Copolymer according to one of the preceding claims, characterized in that the macromolecular chain B comprises units B _to _tre different units B _c , derived from at least one monomer B _at t _re , preferably selected from the units B _N hydrophilic or hydrophobic neutral, derived from a hydrophilic or hydrophobic neutral B _N monomer.

10. Copolymer according to claim 9, characterized in that the macromolecular chain B comprises from 1 to 100%, by weight, of units B _c , preferably from 50% to 100%.

1 1. Copolymer according to one of the preceding claims, characterized in that the macromolecular chain A comprises units _{_A} other than the units A _A, derived from at least one A monomer _to _re t, preferably chosen from hydrophilic or hydrophobic neutral units A _N , derived from a hydrophilic or hydrophobic neutral monomer A _N.

12. Copolymer according to claim 1 1, characterized in that the macromolecular chain A comprises from 1 to 100%, by weight, of A _A units, preferably from 50% to 100%.

13. Copolymer according to one of the preceding claims, characterized in that the weight ratio between the macromolecular chain A and the B part is greater than 1, preferably greater than 2.

14. Copolymer according to one of the preceding claims, characterized in that it has a theoretical average molecular weight of between 500 and 50000 g / mol.

15. Copolymer according to one of the preceding claims, characterized in that the macromolecular chains A and B are bonded to each other by a carbon-carbon bond.

16. Process for the preparation of a copolymer according to one of the preceding claims wherein the copolymer is a block copolymer, preferably linear, comprising at least one block A and at least one block B, where the macromolecular chain A constitutes the block. A and the macromolecular chain B constitutes block B, said method comprising the following steps: step 1): polymerization, preferably by controlled radical polymerization, of monomers so as to obtain a first block chosen from block A and block B, or a precursor block of the first block, step 2): polymerization, preferably by polymerization controlled radical, of monomers so as to obtain at least a second block chosen from block A if a block B or a precursor was obtained in step 1, and block B if a block A or a precursor was obtained at step 1), or a precursor block of the second block, step 3) optional: if precursor blocks were obtained in steps 1) and / or 2), chemical modification of these blocks so as to obtain block A and Block B.

17. The method of claim 16, characterized in that the polymerizations of steps 1) and 2) are implemented by bringing into contact with the monomers, a control agent, and at least one source of free radicals.

18. Method according to one of claims 16 or 17, characterized in that the control agent is an agent having a group of formula -S-CS-, preferably a xanthate having a group of formula -S-CS- O-.

19. Method according to one of claims 16 to 18, characterized in that the block A is prepared in step 1), then the block B in step 2).

20. Method according to one of claims 16 to 19, characterized in that the polymerizations are carried out in solution, preferably in an aqueous medium, alcoholic or hydro-alcoholic.

21. Method according to one of claims 16 to 20, characterized in that

if block B is prepared in step 2) then step 2) is carried out under pH conditions such that the units A _A are in neutral form.

22. Method according to one of claims 16 to 21, characterized in that the block B is prepared by polymerization of monomers comprising cationic monomers B _c .

23. Method according to one of claims 16 to 22, characterized in that the block A is prepared by polymerization of monomers comprising potentially anionic monomers A _A.

24. Method according to one of claims 16 to 23, characterized in that it does not include step 3).

25. Use of the copolymers according to one of claims 1 to 15, in compositions preferably aqueous, comprising a product dispersed or solubilized in the composition.

26. Use according to claim 25 for stabilizing a dispersed product and / or for controlling a stabilization or destabilization of a product under the impact of a change applied to the composition, such as the addition of a compound, the dilution and / or a change in pH, or as a change in temperature.