The invention relates to the preparation of a water-soluble polymer having a molecular weight Mw ranging from 1 000 to 10 000 g / mol and whose polydispersity index I P is less than 3.5. The polymer according to the invention is obtained by polymerization reaction in water of an unsaturated anionic monomer, in the presence of Cu I or Cu II and an aromatic comprising a function chosen from hydroxy compound, primary amine, secondary amine and ternary amine directly bound to the aromatic ring.

The invention also relates to an aqueous composition comprising the polymer according to the invention.

There are many known processes for preparing polymers from monomers, particularly from anionic monomers. Generally, in the preparation of these polymers, it is necessary to search for the molecular weight control weight Mw of the polymer prepared. In particular, it is important to obtain polymers whose molecular weight is relatively low. Similarly, it is necessary to control the polydispersity index I P of the prepared polymers. In particular, this index should be low. During the polymerization reactions carried stake, it is important to eliminate or to significantly limit the use of chain transfer agent.

In the preparation of such polymers from monomers comprising at least one polymerizable olefinic unsaturation, it is important that the polymers obtained include low levels of salts, especially sulfates or phosphorus salts or that these polymers are sigmfîcativement free such salts.

The absence of residual organic solvent in these polymers is also important.

Limiting or eliminating the presence of carbon disulphide or hydrogen sulphide in the produced polymers is also an important feature of these methods of preparation.

WO 2016 066916 and JP H07 138304 relate to the preparation of acrylic polymers but does not mention the advantageous presence during the preparation of a specific aromatic compound.

The polymer of the preparation process according to the invention allows to provide a solution to all or part of the problems of the processes of the prior art.

Thus, the invention provides a process for preparing a water-soluble polymer having a molecular weight Mw ranging from 1 000 to 10 000 g / mol and whose polydispersity index Ip is less than 3.5, by reacting polymerization in water, at a temperature above 60 ° C, of ​​at least one main monomer comprising at least one olefinically unsaturated sand polymerization in the presence:

"At least one metal derivative, complexed, bound to at least one ligand or in ionic form and comprising:

o at least one element (M) selected from Cu I and Cu II ; or

o at least one precursor compound of an element (M);

• at least one aromatic compound (A) comprising at least one function (F) selected from hydroxyl, primary amine, secondary amine and ternary amine directly bound to the aromatic ring, in an amount equivalent to at least 300 ppm based on molar ( F) relative to the molar amount of primary monomer; and

• at least one initiator compound selected from hydrogen peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, alkyl hydroperoxide and mixtures thereof.

Preferably, the polymer prepared according to the invention has a molecular weight Mw less than 9000 g / mol. More preferably, the molecular weight Mw of the prepared polymer is less than 7000 g / mol or less than 6000 g / mol.

Also preferably, the polymer prepared according to the invention has a molecular weight Mw greater than 1 200 g / mol. More preferably, the molecular weight Mw of the prepared polymer is greater than 1 500 g / mol.

Thus, the molecular weight Mw of the polymer may be between 1000 and 9000 g / mol or between 1000 and 8000 g / mol or between 1000 and 6000 g / mol. Preferably, the molecular weight Mw of the polymer may be between

1200 and 9000 g / mol or between 1200 and 8000 g / mol or between 1200 and 6000 g / mol. Also preferably, the molecular weight Mw of the polymer may be between 1500 and 9000 g / mol or between 1500 and 8000 g / mol or between 1500 and 6000 g / mol.

The polydispersity index I P of the polymer prepared according to the invention is less than 3.5. Preferably, the polydispersity index I P is less than 3. According to the invention, the polydispersity index I P can be between 2 and 3.5 or between 2 and 3 or between 2.2 and 3. it can also be between 2.4 and 3, between 2.6 and 3, or between 2.2 and 2.8 or between 2.2 and 2.6.

The method according to the invention is carried out in aqueous medium. Preferably, it may be implemented in the absence of organic solvent. Advantageously, the method according to the invention can be implemented in the raw water or the double-deionized water. It can also be implemented in the system water or in water that is not purified or softened. It can also be used in industrial water.

Also advantageously, the method according to the invention can be implemented in the absence of chain transfer agent.

A particularly advantageous manner when carrying out the process according to the invention, the reaction medium does not include little or salts. In particular, the reaction medium comprises few salts selected from sulfates, sulfites, phosphates, phosphites, hypophosphites. These salts may lead to an alteration of the polymer prepared according to the invention. Preferably, the reaction medium comprises a quantity by weight of sulfates, sulfites, phosphates, phosphites or hypophosphites that is less than 6000 ppm, preferably less than 5000 ppm or 4000 ppm, or less than 1 000 ppm, relative to the quantity by weight of the main monomer.

The method according to the invention comprises the implementation of at least one metal compound comprising an element (M) or a precursor of such an element (M). The metal derivative may be in various forms. Indeed, in the metal compound, the element (M) may be complexed or bonded to at least one ligand or may be in ionic form. Preferably, the element (M) is in the ionic form.

As metal derivative according to the invention, preferred is a compound selected from copper carbonate, copper carbonate hydrate, carbonate of hemi-hydrate, copper acetate, copper sulfate, copper sulfate pentahydrate, copper hydroxide, copper halide .

Outre the loop (M) or a précurseur of a loop (M) présent au sein du Hyper métallique, selon le procédé the invention peut également en œuvre au moins un autre élément de préférence au moins un élément Das Models Fe II , Fe III , Co II , Mn II , Ni II . Fe II and Fe III sont les éléments supplémentaires favorite. Ils peuvent être mis en œuvre sous la forme d'au moins un composé Das Models sulfate de fer, fer sulphate hydrate, sulphate hemi-hydrate fer, fer heptahydrate sulphate, carbonate de fer, fer de carbonate hydrate, carbonate de fer hemi-hydrate, entry fer. Comme composés other links for the mise en oeuvre des éléments supplémentaires, on peut choisir of the manganese acetate tetrahydrate and the cobalt sulphate heptahydrate.

Selon l'invention, the loop (M) peut également être associé à au moins un composé précurseur a loop Das Models Fe II , Fe III , Co II , Mn II , Ni II . Deux éléments (M) peuvent également être associés à au moins un composé précurseur a loop Das Models Fe II , Fe III , Co II , Mn II , Ni II . Comme composés précurseurs des éléments choisis Models Fe II , Fe III , Co II , Mn II , Ni II , on peut citer le sulfate de fer, the sulphate fer hydrate, the sulphate fer hemi-hydrate, the sulphate fer heptahydrate, the carbonate de fer, the carbonate hydrate de fer, the carbonate de fer hemi-hydrate, the entry fer of the manganese acetate tetrahydrate and the cobalt sulphate heptahydrate.

The procédé selon l'invention peut également en œuvre précurseur a composé of a loop (M) associé à au moins un élément Das Models Fe II , Fe III , Co II , Mn II , Ni II ou associé à au moins un composé précurseur a loop Das Models Fe II , Fe III , Co II , Mn II , Ni II .

Lors de l'utilization of a précurseur of a loop (M) or a loop Das Models Fe II , Fe III , Co II , Mn II , Ni II , selon le procédé the invention peut également mettre a jour composé reducer of one ou l'autre des composés précurseurs.

Thus, the method according to the invention can implement an element (M) and at least one precursor compound of an element selected from Fe II , Fe III , Co II , Mn II , Ni II combined with a reducing compound of the compound precursor. It can also implement a compound

precursor of an element (M) associated with a reducing compound of the precursor compound or a precursor compound of an element (M) associated with a reducing compound of the precursor compound and at least one element selected from Fe II , Fe III , Co II , Mn II , Ni II or alternatively a precursor compound of element (M) and at least one precursor compound of an element selected from Fe II , Fe III , Co II , Mn II , Ni II associated with a compound reductant precursor compound.

En présence d'un composé reducer, the composé précurseur of the loop (M) ou bien le composé précurseur a loop Das Models Fe II , Fe II , Co II , Mn II , Ni II permet d'obtenir de préférence in situ, a loop Das Models Cu I , Cu II , Fe II , Fe III , Co II , Mn II , Ni II .

De manière favorite, selon le procédé the invention met jour Cu I and Cu II , or are COMBINÉS. De manière également favorite, selon le procédé the invention met jour Cu I and Fe II , Cu II and Fe II , Cu I and Fe II , Cu II and Fe III , Cu I and Co II , Cu I and Mn II , Cu I and Ni II , Cu II and Co II , Cu II and Ni II , Cu II and Ni II . De manière particulièrement favorite, selon le procédé the invention met jour Cu I and Fe II , Cu II and Fe II , Cu II and Fe III or Cu II and Fe III .

The amount of metal compound used for the process according to the invention may vary relatively widely. Generally for the invention, the method according to the invention implements a molar amount of metal compound which is determined by the number of olefinic unsaturations of the main monomer implemented. Preferably, the method according to the invention implements a molar amount of metal derived from 200 to S 000 ppm, preferably 250 to 4000 ppm, relative to the molar amount of primary monomer.

Similarly, the amount of element selected from Fe II , Fe III , Co II , Mn II , Ni II may vary relatively widely. Preferably, the process according to the invention employs an amount of this additional element of 100 to 3000 molar ppm or from 150 to 2500 molar ppm, based on the molar amount of primary monomer.

Also preferably for the method according to the invention, the additional element can be implemented in a molar ratio ranging from 0.5 to 60 mol%, preferably 2 to 55 mol%, relative to the amount of element (M).

For the process according to the invention, the quantities of precursor compound of the element (M) precursor compound or of the additional element are determined from the respective amounts of the element (M) or of the additional element which must be implemented.

Furthermore a particular metal derivative, the method according to the invention also implements at least one aromatic compound (A) comprising at least one function (F) which is selected from hydroxyl, primary amine, secondary amine and ternary amine. According to the invention, the function (F) is directly linked to the aromatic ring of the aromatic compound (A). The compound (A) may include multiple cycles of which at least one is an aromatic ring. The function (F) is then directly related to one of these aromatic rings.

According to the invention, compound (A) may comprise one or more functions (F).

Preferably according to the invention, the aromatic compound (A) is a hydroxyl compound. More preferably, it is selected from benzoquinone, hydroquinone, catechol, pyrocatechol, t-butylcatechol, gallic acid, tannic acid, tannic liquor, 4-hyroxybcnzoïque acid, 4-aminophenol, salicylic acid, syringic acid, dopamine or dopamine-HCl, resorcinol , lignosulfonate, curcumin, paramethoxyphenol, anthocyanidols, humic acid and mixtures thereof.

According to the invention, compound (A) may also be a ketone derivative of the hydroxy aromatic compound. Such keto derivative may be chosen especially from quinones.

For the process according to the invention, the amount of compound (A) is determined with respect to the number of functions (F) implemented. Thus, the method according to the invention implements the aromatic compound (A) in an amount equivalent to at least 300 ppm based on molar (F) directly linked to the aromatic ring, relative to the molar amount of primary monomer. Preferably, the amount of aromatic compound (A) implementation corresponds to an amount equivalent to at least 325 ppm molar, preferably at least 350 ppm molar, function (F) relative to the molar amount of anionic monomer .

For the process according to the invention, this amount may be greater than 500, 1000 or 5000 ppm relative to the molar amount of anionic monomer. It can reach or exceed 10 000 ppm relative to the molar amount of primary monomer.

Generally for the invention, the method according to the invention implements a molar amount of aromatic compound (A) which is determined depending on the number of unsaturations of olefinic anionic monomer implemented.

The polymer prepared according to the method of the invention is obtained by polymerization in water of reaction of at least one main monomer comprising at least one polymerizable olefinic unsaturation. For the anionic monomer, the polymerizable olefinic unsaturation is preferably a polymerizable ethylenic unsaturation.

Preferably, the main monomer is an anionic monomer including an anionic monomer comprising at least one polymerizable olefinic unsaturation, preferably a polymerizable vinylic function and at least one carboxylic acid function. Thus, and particularly preferably, the inventive polymer is an anionic polymer.

More preferably, the anionic monomer is selected from acrylic acid and methacrylic acid, an acrylic acid salt, methacrylic acid salt. During the implementation of the method according to the invention, these preferred monomers may be combined with an acid selected from maleic acid, itaconic acid, crotonic acid, maleic acid salt, a salt of itaconic acid, crotonic acid salt and mixtures thereof. The preferred anionic monomer according to the invention is acrylic acid, used alone or in combination with another comonomer.

The method according to the invention may also include the implementation of at least one comonomer selected from AMPS, 2-sulfoethyl methacrylate, sodium methallyl sulfonate, styrene sulfonate, salts thereof and a nonionic comonomer.

According to the invention, AMPS acid is 2-acrylamido-2-methylpropane (AMPS) or a salt thereof, such as a salt selected from alkali metal salts such as sodium, potassium or lithium, alkaline earth metal salts such as calcium or magnesium salts, ammonium salts, alkyl ammonium salts such as salts of 2-amino-2-methyl-1-propanol (AMP), d ethanolamine, diethanolamine, triethanolamine. The preferred AMPS salts are the sodium and ammonium salts.

The nonionic comonomer may be selected from esters of an acid selected from acrylic acid, methacrylic acid, maleic acid, itaconic acid, crotonic acid and mixtures thereof. Preferably, the nonionic comonomer may be selected from esters of an acid selected from acrylic acid and methacrylic acid. Advantageously, the comonomer is introduced in an amount by weight less than the amount of primary monomer.

During the implementation of at least one comonomer, the process of the invention employs an amount of metal compound which is determined by the number of olefinic unsaturations in the main monomer and the comonomer used.

Advantageously, the method according to the invention uses at least one initiator compound selected from hydrogen peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, alkyl hydroperoxide and mixtures thereof. The preferred initiator compound is hydrogen peroxide.

Advantageously for the process according to the invention, the polymer obtained may be neutralized. The method according to the invention can therefore also comprise the total or partial neutralization of the prepared polymer. Preferably, the neutralization of the polymer is effected by means of at least one compound selected from alkali metal hydroxides, metal hydroxides, alkaline earth metal, ammonium hydroxide, dihydroxides alkaline earth metal, amines, metal oxides, especially calcium oxide, magnesium oxide and zinc oxide, and mixtures thereof. The total or partial neutralization with sodium or potassium hydroxide is preferred.

The invention also relates to the reaction medium composition implemented for the process according to the invention. Thus, the invention also provides a composition comprising:

• at least one main monomer comprising at least one polymerizable olefinic unsaturation;

• at least one metal derivative, complexed, bound to at least one ligand or in ionic form and comprising:

o at least one element (M) selected from Cu I and Cu II ; or o at least one precursor compound of an element (M);

• at least one aromatic compound (A) comprising at least one function (F) selected from hydroxyl, primary amine, secondary amine and ternary amine directly bound to the aromatic ring, in an amount equivalent to at least

300 ppm molar function (F) relative to the molar amount of primary monomer; and

• at least one initiator compound selected from hydrogen peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, alkyl hydroperoxide and mixtures thereof.

The composition according to the invention may comprise at least one anionic primary monomer and additionally water.

Use of the composition according to the invention for preparing a water soluble polymer, preferably a water-soluble anionic polymer, is also part of the invention.

Moreover a method of preparation, the invention also relates to the polymer prepared in the implementation of this method. Thus, the invention relates to an at least one main monomer polymer comprising at least one polymerizable olefinic unsaturation, having a molecular weight Mw of less than 10000 g / mol and whose polydispersity index I P is less than 3.5 . According to the invention, the polymer may be in acid form or neutralized form. The polymer according to the invention in acid form can be neutralized by means of at least one compound selected from alkali metal hydroxides, alkaline earth metal hydroxides, ammonium hydroxide, alkaline dihydroxides tcrreux metal, amines, metal oxides including calcium oxide, magnesium oxide and zinc oxide, and mixtures thereof. The total or partial neutralization with sodium or potassium hydroxide is preferred.

Particularly advantageously, the polymer according to the invention does not include residual volatile organic compound.

Also particularly advantageous manner, the polymer according to the invention comprises an amount of salt selected from sulfates, sulfites, phosphates, phosphites, hypophosphites which is less than 2000 ppm relative to the amount of primary monomer. Preferably, this amount is less than 1 500 ppm or even less than 1000 ppm, relative to the amount of primary monomer.

The particular, advantageous or preferred features defined for the process according to the invention define polymers, compositions or uses of the invention which are specific advantageous or preferred.

According to the invention, the molecular weight of the polymers is determined by steric exclusion chromatography (CES) or English "Gel Permeation Chromatography" (GPC). This technique uses a Waters brand liquid chromatograph equipped with a detector. This detector is a refractive concentration detector Waters brand. This liquid chromatography apparatus has a size exclusion column to separate the different molecular weights of the copolymers studied. The elution liquid phase is an aqueous phase adjusted to pH 9.00 using sodium hydroxide IN 0.0 containing 5M NaHCCh, NaNCb 0.1M, 0.02M triethanolamine and 0.03% NaN3.

In a first step, 0.9% dry diluted copolymer solution in the ESC of the solubilization solvent, which corresponds to the elution liquid phase of the ESC to which is added 0.04% of dimethylformamide playing the role of flow marker or internal standard. Then, filtered to 0.2 μιη. 100 uL are then injected into the chromatograph (eluent: an aqueous phase adjusted to pH 9.00 by N sodium hydroxide containing 0.05 M NaHCO, 0.1 M Nanos, 0.02M triethanolamine and 0.03% NaN 3 ).

The liquid chromatography apparatus contains an isocratic pump (Waters 515) whose flow rate is set at 0.8 mL / min. The chromatography apparatus further comprises an oven which itself comprises in series the following column system: a type precolumn Guard Column Ultrahydrogel Waters 6 cm in length and 40 mm internal diameter, and a linear type column Waters Ultrahydrogel 30 cm length and 7.8 mm internal diameter. The detection system comprises a detector

réfractornétrique type RI Waters 410 The furnace is brought to ia temperature of 60 ° C and a refractometer is brought to fa temperature of 45 ° C.

The chromatograph is calibrated using sodium polyacrylate standards powder of different molecular weights certified by the supplier: Polymer Standards Service or Standard American Polymers Corporation.

The following examples illustrate various aspects of the invention.

In a reactor of 1000 ml equipped with a mechanical stirrer and an oil bath with heating and a temperature measuring system for the temperature regulation was charged with a mixture (1) defined in Tables 1 2 and 3. the aromatic compound (A) is introduced into the reactor (1). The reactor is then heated to a temperature of 93 ± 2 ° C.

When this temperature is reached, peristaltic pumps equipping the reactor allow to simultaneously inject the mixture (2) and the mixture (3) previously prepared and defined in Tables 1, 2 and 3 is maintained a temperature of 93 ± 2 ° C.

The injection time of the mixture (1) was 120 min and the injection time of the mixture (3) is 150 min. After completing the injection, the reactor is allowed to cool.

Molecular weight Mw and polydispersity index I P are measured and calculated after complete neutralization with soda polymer samples prepared.

The characteristics of the inventive polymers and comparative polymers are shown in Tables 1, 2 and 3 (amounts in g).

claims
1. A process for preparing a water-soluble polymer, the molecular weight Mw (determined by SEC) is from 1 000 to 10 000 g / mol and whose polydispersity index I P is less than 3.5, by polymerization reaction in water at a temperature above 60 ° C, of at least one main monomer comprising at least one polymerizable olefinic unsaturation in the presence:

• at least one metal derivative, complexed, bound to at least one ligand or in ionic form and comprising:

o at least one element (M) selected from Cu I and Cu II ; or

o at least one precursor compound of an element (M);

• at least one aromatic compound (A) comprising at least one function (F) selected from hydroxyl, primary amine, secondary amine and ternary amine directly bound to the aromatic ring, in an amount equivalent to at least 300 ppm based on molar ( F) relative to the molar amount of primary monomer; and

• at least one initiator compound selected from hydrogen peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, alkyl hydroperoxide and mixtures thereof.

2. The method of claim 1 wherein:

• the molecular weight Mw of the polymer is less than 9000 g / mol, preferably less than 7000 or less than 6000 g / mol; or

• the molecular weight Mw of the polymer is greater than 1 200 g / mol, preferably greater than 1500 g / mol; or

• the polydispersity index Ip of the polymer is less than 3 or is between 2 and 3.5 or between 2 and 3 or between 2.2 and 3, between 2.4 and 3, between 2.6 and 3, or between 2.2 and 2.8 or between 2.2 and 2.6.

3. A method according to one of claims 1 and 2 comprising the implementation:

• at least one metal compound selected from copper carbonate, hydrated copper carbonate, hemi-hydrated copper carbonate, copper acetate, sulfate

copper, iron sulfate, iron sulfate hydrate, sulphate hemi-hydrate iron, iron carbonate, iron carbonate hydrated, hemi-hydrated iron carbonate, copper hydroxide; or

• the aromatic compound (A) in an amount equivalent to at least 325 ppm molar, preferably at least 350 ppm molar, function (F) relative to the molar amount of primary monomer.

4. A method according to one of claims 1 to 3 implementing:

• a loop (M) et au moins un élément Das Models Fe II , Fe III , Co II , Mn II , Ni II ; or

• a loop (M) et au moins un composé précurseur a loop Das Models Fe II , Fe III , Co II , Mn II , Ni II ; or

• a precursor compound of an element (M); or

• a composé précurseur of a loop (M) et au moins un élément Das Models Fe II , Fe III , Co II , Mn II , Ni II ; or

• a composé précurseur of a loop (M) et au moins un composé précurseur a loop Das Models Fe II , Fe III , Co II , Mn II , Ni II ; or

• an element (M) and at least one precursor compound of an element selected from Fe II , Fe III , Co II , Mn II , Ni II combined with a reducing compound of precursor compound; or

• a precursor compound of an element (M) associated with a reducing compound of precursor compound; or

• a composé précurseur of a loop (M) associé a reducer composé composé du précurseur et au moins un élément Das Models Fe II , Fe ra , Co II , Mn II , Ni II ; or

• a precursor compound of an element (M) and at least one precursor compound of an element selected from Fe II , Fe III , Co II , Mn II , Ni II combined with a reducing compound of precursor compound.

5. A method according to one of claims 1 to 4 wherein the aromatic compound (A) is hydroxylated, preferably selected from benzoquinone, hydroquinone, catechol, pyrocatechol, t-burylpyrocatechol, gallic acid, tannic acid, tannic liquor, 4-hyroxybenzoique acid, 4-aminophenol, salicylic acid, syringic acid, dopamine or dopamine-HCl, resorcinol, lignosulfonate, curcumin, paramethoxyphenol, anthocyanidols, mimicry acid and mixtures thereof.

6. Method according to one of claims 1 to 5 wherein the principal monomer is an anionic monomer, preferably an anionic monomer comprising at least one polymerizable olefinic unsaturation, preferably a polymerizable vinyl function, and at least one carboxylic acid function, preferably the anionic monomer is selected from acrylic acid and methacrylic acid, an acrylic acid salt, methacrylic acid salt, optionally combined with an acid selected from maleic acid, itaconic acid, crotonic acid, maleic acid salt, a salt of itaconic acid, a crotonic acid salt, and mixtures thereof, more preferably acrylic acid.

7. A method according to one of claims 1 to 6 further comprising the implementation of at least one comonomer, preferably at least one comonomer selected from AMPS, 2-sulfoethyl methacrylate, sodium methallyl sulfonate, styrene sulfonate and their salts and a nonionic comonomer, more preferably selected from esters of an acid selected from acrylic acid, methacrylic acid, maleic acid, itaconic acid, crotonic acid and mixtures thereof, more preferably acrylic acid and methacrylic acid,

8. A method according to one of claims 1 to 7 implemented in the raw water or the double-deionized water.

9. A method according to one of claims 1 to 8 carried out in the absence of chain transfer agent.

10. Method according to one of claims 1 to 9 carried out in aqueous medium or in the absence of organic solvent or conducted in an aqueous medium and in the absence of organic solvent.

11. A method according to one of claims 1 to 10 wherein the reaction medium does not include little or, preferably comprises a quantity by weight of less than 6000 ppm, preferably less than 5000 ppm or 4000 ppm, or even less to 1000 ppm, relative to the quantity by weight of the main monomer, salt selected from sulfates, sulfites, phosphates, phosphites, hypophosphites.

12. Method according to one of claims 1 to 11 also comprising the total or partial neutralization of the polymer, preferably by means of at least one compound selected

among alkali metal hydroxides, alkaline earth metal hydroxides, ammonium hydroxide, dihydroxides alkaline earth metal, amines, metal oxides including calcium oxide, magnesium oxide and zinc oxide, and mixtures thereof.

13. A polymer of at least one main monomer comprising at least one polymerizable olefinic unsaturation, having a molecular weight Mw (determined by SEC) is less than 10 000 g / mol and whose polydispersity index I P is less than 3, 5, obtained according to the method of one of claims 1 to 12 and containing no residual volatile organic compound or comprising an amount of salt selected from sulfates, sulfites, phosphates, phosphites, hypophosphites which is less than 2000 ppm, preferably less than 1 500 ppm or even less than 1000 ppm, relative to the amount of primary monomer.

14. A composition comprising:

"At least one main monomer comprising at least one polymerizable olefinic unsaturation;

• at least one metal derivative, complexed, bound to at least one ligand or in ionic form and comprising:

o at least one element (M) selected from Cu I and Cu II ; or

o at least one precursor compound of an element (M);

• at least one aromatic compound (A) comprising at least one function (F) selected from hydroxyl, primary amine, secondary and amino ternary directly linked to the aromatic ring amine, in an amount equivalent to at least 300 ppm molar function (F) relative to the molar amount of primary monomer; and

· At least one initiator compound selected from hydrogen peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, alkyl hydroperoxide and mixtures thereof.

15. The composition of claim 14 comprising at least one anionic primary monomer and additionally water.

16. Use of a composition according to one of claims 14 and 15 for the preparation of a water soluble anionic polymer.