Copolymère thioester

Abstract

The invention relates to a thioester copolymer prepared using an unsaturated carboxylic acid and a thionolactone by a radical ring-opening polymerization reaction in aqueous medium. The copolymer according to the invention is biodegradable and can be used as a dispersing agent for particles of a mineral material in an aqueous composition.

Description

Title of the invention: Thioester copolymer

[0001] The invention relates to a thioester copolymer prepared using an unsaturated carboxylic acid and a thionolactone by a radical ring-opening polymerization reaction in aqueous medium. The copolymer according to the invention is degradable and can be used as a dispersing agent for mineral particles in an aqueous composition.

[0002] Many technical fields require the use of polymers chosen for their specific properties. In particular, the field of mineral processing, especially the dispersion or grinding of mineral matter, uses dispersing agents or grinding aids. Similarly, the fields of water treatment and detergents use polymers capable of interacting with mineral materials.

[0003] In addition to their functional properties, these polymers must be able to degrade once they have been used. Preferably, they must be able to degrade in a controlled manner or in a natural manner.

[0004] Moreover, the methods of preparing these polymers play an essential role for their effectiveness but also for their implementation conditions, in particular when it comes to limiting or banning the use of polluting or hazardous substances.

[0005] Numerous methods for preparing polymers are known, including methods for preparing thioester copolymers. Organic solvents are commonly used in these methods.

[0006] Thus, there is a significant need for efficient polymers that can be prepared using improved methods. Control of the polymer's molecular mass is also a priority. Prior art polymers and their preparation methods are not always satisfactory in addressing all or some of the problems encountered.

[0007] Thus, the invention provides a thioester copolymer P prepared in aqueous medium, at a temperature above 50°C, by a radical ring-opening polymerization reaction: - of at least one anionic compound (a) comprising at least one polymerizable olefinic unsaturation and at least one carboxylic acid function or one of its salts; - of at least one compound (b) chosen from among the thionolactones, in the presence of at least one radical-generating compound.

[0008] The composition of the copolymer P according to the invention may vary. Preferably, The copolymer P according to the invention comprises 70 mol% to 98 mol% of residue of compound (a), preferably 70 mol% to 95 mol% of residue of compound (a) or 75 mol% to 95 mol% of residue of compound (a), more preferably 80 mol% to 90 mol% of residue of compound (a) or 85 mol% to 90 mol% of residue of compound (a), relative to the molar amount of residues of compounds (a) and (b).

[0009] Also preferably, the copolymer P according to the invention comprises 2 mol% to 30 mol% of residue of compound (b), preferably 5 mol% to 30 mol% of residue of compound (b) or 5 mol% to 25 mol% of residue of compound (b), more preferably 10 mol% to 20 mol% of residue of compound (b) or 10 mol% to 15 mol% of residue of compound (b), relative to the molar amount of residues of compounds (a) and (b).

[0010] More preferably, the copolymer P according to the invention comprises: - from 70 mol% to 98 mol% of compound residue (a) and from 2 mol% to 30 mol% of compound residue (b), preferably: - from 70 mol% to 95 mol% of compound residue (a) and from 5 mol% to 30 mol% of compound residue (b) or - from 75 mol% to 95 mol% of compound residue (a) and from 5 mol% to 25 mol% of compound residue (b), more preferably: - from 80 mol% to 90 mol% of compound residue (a) and from 10 mol% to 20 mol% of compound residue (b) or - from 85% molar to 90% molar of compound residue (a) and from 10% molar to 15% molar of compound residue (b), compared to the molar quantity of residues of compounds (a) and (b).

[0011] Preferably according to the invention, the copolymer P is water-soluble. Advantageously, a water-soluble polymer is a polymer capable of forming a solution in water. Generally, the solubility of polymers in water arises from the presence of hydrophilic groups.

[0012] Essentially, according to the invention, the copolymer P is prepared by means of at least one anionic compound (a) comprising at least one polymerizable olefin unsaturation and at least one carboxylic acid function or one of its salts. Preferably, for the copolymer P according to the invention, the compound (a) comprises one or two carboxylic acid functions, preferably comprising a single carboxylic acid function.

[0013] More preferably for the copolymer P according to the invention, the compound (a) is chosen from acrylic acid, methacrylic acid, a salt of acrylic acid, a salt of methacrylic acid and their combinations, more preferably acrylic acid.

[0014] For the preparation of the copolymer P according to the invention, the polymerization reaction may implement at least one other compound chosen from: * another anionic compound (c), preferably a compound (c) selected from itaconic acid, maleic acid, maleic anhydride and their combinations; * a compound (d) selected from 2-acrylamido-2-methylpropane sulfonic acid, a salt of 2-acrylamido-2-methylpropane sulfonic acid, 2-(methacryloyloxy)ethanesulfonic acid, a salt of 2-(methacryloyloxy)ethanesulfonic acid, sodium methallyl sulfonate, styrene sulfonate and combinations thereof; * a non-ionic compound (e) comprising at least one polymerizable olefinic unsaturation, preferably at least one polymerizable ethylenic unsaturation, and in particular a polymerizable vinyl function, more preferably a non-ionic compound (e) selected from styrene, vinylcaprolactam, esters of an acid comprising at least one monocarboxylic acid function, in particular an ester of an acid selected from acrylic acid, methacrylic acid, and combinations thereof, for example hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, alkyl acrylate, in particular Ci-Cio-alkyl acrylate, preferably Ci-C4-alkyl acrylate, more preferably methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, isobutyl acrylate, n-butyl acrylate, alkyl methacrylate, in particular methacrylate Ci-Cio-alkyl, preferably Ci-C4-alkyl methacrylate,more preferably methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, n-butyl methacrylate, aryl acrylate, preferably phenyl acrylate, benzyl acrylate, phenoxyethyl acrylate, aryl methacrylate, preferably phenyl methacrylate, benzyl methacrylate, phenoxyethyl methacrylate; , * a compound (f) of formula I: [Chem I] R1 in which: - R1 and R2, whether identical or different, independently represent H or CH3. - L1 independently represents a grouping chosen from C(O), CH2, CH2-CH2 and o-ch2-ch2-ch2-ch2, - L2 independently represents a group chosen from (CH2-CH2O)X, (CH2 CH(CH3)O)y, (CH(CH3)CH2O)z and their combinations and - x, y and z, identical or different, independently represent 0 or an integer or decimal number between 1 and 150 and the sum x+y+z is between 10 and 150; * a crosslinking compound (g) or a compound (g) comprising at least two olefinic unsaturations; preferably in an amount of less than 5% by weight, also preferably from 0.01 to 4% by weight, in particular from 0.02 to 4% by weight or from 0.02 to 2% by weight, in particular from 0.02 to 1% by weight, of monomer (g) relative to the total amount by weight of monomers.

[0015] Essentially according to the invention, the copolymer P is prepared using at least one compound (b) selected from among the thionolactones. Preferably for the copolymer P according to the invention, the compound (b) is a cyclic thionolactone, preferably a cyclic thionolactone comprising at least 5, 6 or 7 members in the ring, in particular a cyclic thionolactone comprising 5 to 16 members, preferably 5 to 10 members, in the ring.Preferably for the copolymer P according to the invention, compound (b) is a thionolactone selected from dibenzo[c,e]oxepane-5-thione (DOT, CAS number 4445-34-5), γ-thionobutyrolactone (TBL), β-thionovalerolactone (TVL), co-thionopentadecalactone (TPDL), ε-thionocaprolactone (TCL), substituted ε-thionocaprolactone (thCL), 3,3-dimethyl-2,3-dihydro-5H-benzo[e][l,4]dioxepine-5-thione (DBT), thionoiso-chromanone (TIC), 3,6-dimethyl-5-thioxo-l,4-dioxan-2-one (TLD), 5-phenyloxolane-2-thione, 2-benzofuran-l(3H)-thione, l-sulfanylidene-l,3-dihydro-2-benzofuran-5-carbonitrile, 6-nitro-2-benzofuran-l(3H)-thione, 3-ethyl-2-benzofuran-l(3H)-thione, dibenzo[c,e]oxepine-5(7H)-thione and their combinations.

[0016] According to the invention, the quantities of compounds (a) and (b) used can vary. Preferably according to the invention, the polymerization reaction uses from 70 mol% to 98 mol% of compound (a), preferably from 70 mol% to 95 mol% of compound (a) or from 75 mol% to 95 mol% of compound (a), more preferably from 80 mol% to 90 mol% of compound (a) or from 85 mol% to 90 mol% of compound (a), relative to the mol% of compounds (a) and (b).

[0017] Also preferably according to the invention, the polymerization reaction uses 2 mol% to 30 mol% of compound (b), preferably 5 mol% to 30 mol% of compound (b) or 5 mol% to 25 mol% of compound (b), more preferably 10 mol% to 20 mol% of compound (b) or 10 mol% to 15 mol% of compound (b), relative to the mol% of compounds (a) and (b).

[0018] More preferably according to the invention, the polymerization reaction involves: - from 70 mol% to 98 mol% of compound (a) and from 2 mol% to 30 mol% of compound (b), preferably: - from 70 mol% to 95 mol% of compound (a) and from 5 mol% to 30 mol% of compound (b) or - from 75 mol% to 95 mol% of compound (a) and from 5 mol% to 25 mol% of compound (b), more preferably: - from 80 mol% to 90 mol% of compound (a) and from 10 mol% to 20 mol% of compound (b) or - from 85 mol% to 90 mol% of compound (a) and from 10 mol% to 15 mol% of compound (b), relative to the molar amount of compounds (a) and (b).

[0019] During the polymerization reaction, the reaction conditions may vary. Preferably for the copolymer P according to the invention, the polymerization reaction is carried out at a temperature below 120°C, preferably below 100°C.

[0020] Also preferably for the copolymer P according to the invention, the polymerization reaction is carried out in water, alone or in a mixture with at least one polar, protic solvent, preferably an alcohol, more preferably isopropanol. Preferably according to the invention, a mixture of water and organic solvent may respectively comprise equal weight proportions of water and organic solvent or comprise a majority of water, for example 60% by weight, 70% by weight, or 80% by weight of water. Preferably according to the invention, the polymerization reaction is carried out in water and in the absence of organic solvent.

[0021] According to the invention, the thioester copolymer P is prepared by a polymerization reaction in the presence of at least one radical-generating compound. The polymerization reaction may be an electrochemical polymerization reaction, an ultrasonic polymerization reaction, or an irradiation polymerization reaction, particularly under UV irradiation.

[0022] According to the invention, a radical-generating compound is present during the polymerization reaction. Preferably according to the invention, the radical-generating compound is selected from 4,4'-azobis-4-cyanopentanoic acid (ACPA or 4,4'-azobis-(4-cyanovaleric acid) or AZDN or 2,2'-azobisisobutyronitrile), hydrogen peroxide, benzoyl peroxide, acetyl peroxide, lauryl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, ammonium persulfate, an alkali metal persulfate (in particular sodium persulfate, potassium persulfate), an azo compound and their respective combinations or associations with an ion selected from Fe11, Fe111, Cu1, Cu11 and their combinations. According to the invention, the Fe11, Fe111, Cu1, Cu11 ions can be implemented by means of at least one compound selected from iron sulfate, hydrated iron sulfate, hemihydrated iron sulfate, heptahydrated iron sulfate, iron carbonate, hydrated iron carbonate, hemi- hydrated, iron chloride, copper carbonate, hydrated copper carbonate, hemihydrated copper carbonate, copper acetate, copper sulfate, pentahydrated copper sulfate, copper hydroxide, copper halide.

[0023] Also preferably according to the invention, the radical-generating compound is selected from 4,4'-azobis-4-cyanopentanoic acid (ACPA), sodium persulfate, 2,2'-azobis(2-(4,5-dihydroimidazolyl)propane, 2,2'-azobis(2-methylpropionamidine) dihydrochloride, diazovalero-nitrile.

[0024] According to the invention, the radical-generating compound is more preferably chosen from 4,4'-azobis-4-cyanopentanoic acid (ACPA), hydrogen peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, particularly sodium persulfate.

[0025] According to the invention, the polymerization reaction can be carried out in the presence of a compound comprising phosphorus in oxidation state I, in particular hy-pophosphorous acid (H3PO2) or a derivative of hypophosphorous acid (H3PO2), such as compounds comprising at least one hypophosphite ion (H2PO2), in particular a compound selected from sodium hypophosphite (H2PO2Na), potassium hypophosphite (H2PO2K), calcium hypophosphite ([H2PO2]2Ca).

[0026] According to the invention, the polymerization reaction can be carried out in the presence of a compound comprising phosphorus in oxidation state III, in particular phosphorous acid or a derivative of phosphorous acid.

[0027] According to the invention, the polymerization reaction can also be carried out in the presence of a compound comprising a bisulfite ion, preferably sodium bisulfite or potassium bisulfite,

[0028] According to the invention, the radical-generating compound can also be associated with at least one radical-controlled polymerization transfer agent, in particular a RAFT (reversible addition-fragmentation chain transfer) type transfer agent. The polymerization reaction can be carried out in the presence of a mercaptan compound, in particular a mercaptan compound comprising at least 4 carbon atoms such as butylmercaptan, n-octylmercaptan, n-dodecyl-mercaptan, tert-dodecyl-mercaptan, isooctyl 3-mercaptopropionate, or a trithiocarbonate compound. Preferably, according to the invention, the trithiocarbonate compound is a compound of formula II: [chem II] R g R XOOC X coox in which X independently represents H, Na, or K, and R represents inde- pendant a Ci-C5-alkyl group, preferably a Ci-C3-alkyl group, more preferably a methyl group; the preferred compound of formula II is dipropionate trithiocarbonate disodium (DPTTC - CAS No. 86470-33-2) or dipropyl trithiocarbonate (DPTTC, CAS No. 6332-91-8).

[0029] The mass of the copolymer P according to the invention can vary. Preferably, the copolymer P according to the invention has a molecular mass in weight Mw, measured by CES, ranging from 800 g / mol to 100,000 g / mol; more preferably from 800 g / mol to 80,000 g / mol or from 800 g / mol to 60,000 g / mol; much more preferably from 1,000 g / mol to 80,000 g / mol or from 1,000 g / mol to 60,000 g / mol. Much more preferably, this mass ranges from 1,000 g / mol to 30,000 g / mol or from 1,000 g / mol to 20,000 g / mol; even more preferably from 1,000 g / mol to 15,000 g / mol.

[0030] According to the invention, the molecular weight Mw is determined by Size Exclusion Chromatography (SEC), also known as Gel Permeation Chromatography (GPC). This technique employs a Waters brand liquid chromatography instrument equipped with a detector. This detector is a Waters brand refractometric concentration detector. This liquid chromatography apparatus is equipped with 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 1 N sodium hydroxide containing 0.05 M NaHCO3, 0.1 M NaNO3, 0.02 M triethanolamine, and 0.03% NaN3.

[0031] According to a first step, the copolymer solution is diluted to 0.9% dry in the solubilizing solvent of the CES, which corresponds to the liquid elution phase of the CES, to which 0.04% dimethylformamide is added, which acts as a flow marker or internal standard. Then, it is filtered at 0.2 µm. 100 pL are then injected into the chromatography apparatus (eluent: an aqueous phase adjusted to pH 9.00 with sodium hydroxide (IN) containing 0.05 M NaHCO3, 0.1 M NaNO3, 0.02 M triethanolamine and 0.03% NaN3).

[0032] The liquid chromatography apparatus includes an isocratic pump (“Waters” 515) with a flow rate set at 0.8 mL / min. The chromatography apparatus also includes an oven which itself comprises, in series, the following column system: a 6 cm long, 40 mm internal diameter “Guard Column Ultrahydrogel Waters” pre-column and a 30 cm long, 7.8 mm internal diameter “Ultrahydrogel Waters” linear column. The detection system consists of a “RI Waters” 410 refractometer detector. The oven is heated to 60°C and the refractometer to 45°C. The chromatography apparatus is calibrated using powdered sodium polyacrylate standards of various molecular weights certified by the supplier: Polymer Standards Service or American Polymers Standards Corporation (molecular weight). lecular ranging from 900 to 2,250,000 g / mol and polydispersity index ranging from 1.4 to 1.7).

[0033] The method for preparing copolymer P according to the invention is particularly advantageous. Thus, the invention also provides a method for preparing a copolymer P according to the invention by a radical ring-opening polymerization reaction in an aqueous medium and at a temperature above 50°C: - of at least one anionic compound (a) comprising at least one polymerizable olefinic unsaturation and at least one carboxylic acid function or one of its salts; - of at least one compound (b) chosen from among the thionolactones, in the presence of at least one radical-generating compound.

[0034] The properties of the copolymer P according to the invention make it particularly useful in many technical fields, in particular in the fields of preparation or use of suspensions of mineral particles, especially aqueous suspensions of mineral particles.

[0035] Thus, the invention also provides a dispersing agent comprising at least one copolymer P according to the invention and at least one solid or liquid support, preferably water, alone or in combination with at least one other substance, for example at least one surfactant compound.

[0036] The use of the copolymer P or the dispersing agent according to the invention makes it possible to provide a method for dispersing a mineral material comprising the introduction of at least one copolymer P according to the invention or at least one dispersing agent according to the invention into a composition, preferably an aqueous composition, comprising particles of a mineral material. Preferably according to the invention, this is a synthetic or naturally occurring mineral material, preferably selected from alkaline earth metal carbonate, preferably calcium carbonate (natural calcium carbonate or precipitated calcium carbonate), strontium carbonate, magnesium carbonate, barium carbonate and their combinations, dolomite, kaolin, titanium dioxide, talc, lime, calcium sulfate, barium sulfate, tartar and their combinations.

[0037] Preferably, for the dispersion method according to the invention, the copolymer P is degradable, preferably degradable in a controlled and well-natural manner, more preferably biodegradable. More preferably, according to the invention, the copolymer P is degradable in a basic or acidic medium.

[0038] The method for preparing copolymer P according to the invention comprises the polymerization reaction of the anionic compound (a) with the compound (b) which is selected from among the thionolactones. The resulting copolymer P is degradable. Thus, the invention also provides a method for degrading a thioester copolymer P comprising the treatment by means of at least one basic compound or by means of at least one acidic compound of the copolymer P prepared in aqueous medium, at a temperature above 50°C, by a radical ring-opening polymerization reaction: - of at least one anionic compound (a) comprising at least one polymerizable olefinic unsaturation and at least one carboxylic acid function or of one of its salts; - of at least one compound (b) chosen from among the thionolactones, in the presence of at least one radical-generating compound.

[0039] Preferably according to the invention, the method of degrading the copolymer P leads to a degraded polymer Pd. Thus, the invention also provides a method for preparing a polymer Pd by acid degradation or by basic degradation of a thioester copolymer P prepared in aqueous medium, at a temperature above 50°C, by a radical ring-opening polymerization reaction: - of at least one anionic compound (a) comprising at least one polymerizable olefinic unsaturation and at least one carboxylic acid function or one of its salts; - of at least one compound (b) chosen from among the thionolactones, in the presence of at least one radical-generating compound.

[0040] Preferably for the degradation method according to the invention, the degraded polymer, respectively the Pd polymer, has a weight molecular mass Mw, measured by CES, reduced by 10%, preferably reduced by 25% or reduced by 40%, more preferably reduced by 50% or reduced by 60%, much more preferably reduced by 75% or reduced by 90%, compared to the weight molecular mass Mw of the P copolymer.

[0041] The particular, advantageous or preferred characteristics of the copolymer P according to the invention define methods of preparing the copolymer P, a dispersing agent, a method of dispersing a mineral material, a method of degrading a thioester copolymer P and a method of preparing a polymer Pd which are also particular, advantageous or preferred.

[0042] The following examples illustrate the different aspects of the invention, in particular the preparation and characterization of thioester P copolymers according to the invention.

[0043] EXAMPLES

[0044] PI polymer according to the invention

[0045] In a two-necked flask, a 1:1 v / v isopropanol / water mixture (6.94 mL) and acrylic acid (AA, 0.5 g, 6.94 mmol) are introduced. Then, dibenzo[c,e]oxepane-5-thione (DOT, 0.0785 g, 0.347 mmol) and 4,4'-azobis-4-cyanopentanoic acid (ACPA, 0.0078 g, 0.0278 mmol) are added. After After stirring for 25 minutes, the flask is placed in an oil bath heated to 80°C and stirred at 325 rpm for 4 hours. The mixture is then allowed to cool to room temperature, yielding the PI polymer with a molecular weight Mw, measured by CES, of 14,730 g / mol and a polydispersity index of 1.7.

[0046] P2 polymer according to the invention

[0047] In a two-necked flask, a 1:1 v / v isopropanol / water mixture (6.94 mL) and acrylic acid (AA, 0.5 g, 6.94 mmol) are introduced. Then, dibenzo[c,e]oxepane-5-thione (DOT, 0.039 g, 0.176 mmol) and 4,4'-azobis-4-cyanopentanoic acid (ACPA, 0.0078 g, 0.0278 mmol) are added. After stirring for 25 minutes, the flask is placed in an oil bath heated to 80°C and stirred at 325 rpm for 4 hours. The mixture is allowed to cool to room temperature, yielding polymer P2 with a molecular weight Mw, measured by CES, of 12,500 g / mol and a polydispersity index of 1.7.

[0048] P3 polymer according to the invention

[0049] In a two-necked round-bottom flask, a 1:1 v / v isopropanol / water mixture (6.94 mL) and acrylic acid (AA, 0.5 g, 6.94 mmol) are introduced. Then, dibenzo[c,e]oxepane-5-thione (DOT, 0.039 g, 0.176 mmol) and potassium persulfate (0.0075 g, 0.0277 mmol) are added. After stirring for 25 minutes, the flask is placed in an oil bath heated to 80°C and stirred at 325 rpm for 4 hours. The mixture is allowed to cool to room temperature, yielding polymer P3 with a molecular weight Mw, measured by CES, of 13,860 g / mol and a polydispersity index of 1.7.

[0050] Polymer degradation according to the invention

[0051] 20 mg of PI polymer are dissolved in 1 mL of water and then propylamine (20 mg) is added. The mixture is stirred for 24 hours at room temperature, then the degraded polymer Pdl is dried under a hood and analyzed by CES to measure its molecular mass Mw, which is 11,000 g / mol, and its polydispersity index of 1.7.

[0052] Similarly, the P2 and P3 polymers are degraded to obtain the degraded polymers Pd2 (Mw of 9,900 g / mol and Ip of 1.7) and Pd3 (Mw of 10,810 g / mol and Ip of 1.6).

[0053] The decrease in the measured masses confirms that the P polymers according to the invention are degradable in a controlled manner.

Claims

Claims

1. Thioester copolymer P prepared in an aqueous medium, at a temperature above 50°C, by a radical ring-opening polymerization reaction: - of at least one anionic compound (a) comprising at least one polymerizable olefinic unsaturation and at least one carboxylic acid function or one of its salts; - of at least one compound (b) chosen from thionolactones, in the presence of at least one radical-generating compound.

2. Copolymer P according to claim 1 comprising: - from 70 mol% to 98 mol% of residue of compound (a), preferably from 70 mol% to 95 mol% of residue of compound (a) or from 75 mol% to 95 mol% of residue of compound (a), more preferably from 80 mol% to 90 mol% of residue of compound (a) or from 85 mol% to 90 mol% of residue of compound (a), or - from 2 mol% to 30 mol% of residue of compound (b), preferably from 5 mol% to 30 mol% of residue of compound (b) or from 5 mol% to 25 mol% of residue of compound (b), more preferably from 10 mol% to 20 mol% of residue of compound (b) or from 10 mol% to 15 mol% of residue of compound (b), relative to the molar amount of residues of compounds (a) and (b).

3. Copolymer P according to one of claims 1 or 2 for which: - the compound (a) comprises one or two carboxylic acid functions, preferably comprises a single carboxylic acid function, - preferably, the compound (a) is chosen from acrylic acid, methacrylic acid, an acrylic acid salt, a methacrylic acid salt and combinations thereof, more preferably acrylic acid; or for which: - the polymerization reaction also uses at least one other compound chosen from: * another anionic compound (c), preferably a compound (c) chosen from itaconic acid, maleic acid, maleic anhydride and combinations thereof; * a compound (d) selected from 2-acrylamido-2-methylpropane sulfonic acid, a salt of 2-acrylamido-2-methylpropane sulfonic acid, 2-(methacryloyloxy)ethanesulfonic acid, a salt of 2-(methacryloyloxy)ethanesulfonic acid, sodium methallyl sulfonate, styrene sulfonate and combinations thereof; * a non-ionic compound (e) comprising at least one polymerizable olefinic unsaturation, preferably at least one polymerizable ethylenic unsaturation and in particular a polymerizable vinyl function, more preferably a non-ionic compound (e) chosen from styrene, vinylcaprolactam, esters of an acid comprising at least one monocarboxylic acid function, in particular an ester of an acid chosen from acrylic acid, methacrylic acid, and combinations thereof, for example hydroxyethylacrylate, hydroxypropylacrylate, hydroxyethylmethacrylate, hydroxypropylmethacrylate, alkyl acrylate, in particular C1-C10-alkyl acrylate, preferably C1-C4-alkyl acrylate, more preferably methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, isobutyl acrylate, n-butyl acrylate, alkyl meth ... Ci-Cio-alkyl, preferably C1-C4-alkyl methacrylate,more preferably methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, n-butyl methacrylate, aryl acrylate, preferably phenylacrylate, benzylacrylate, phenoxyethylacrylate, aryl methacrylate, preferably phenylmethacrylate, benzylmethacrylate, phenoxyethylmethacrylate;, * a compound (f) of formula I: [Chem I] R1 in which: - R1 and R2, identical or different, independently represent H or CH3, - L1 independently represents a group chosen from C(O), CH2, CH2-CH2 and O-CH2-CH2-CH2-CH2, - L2 independently represents a group chosen from (CH2-CH2 O)x, (CH2CH(CH3)O)y, (CH(CH3)CH2O)z and their combinations and - x, y and z, identical or different, independently represent 0 or an integer or decimal number between 1 and 150 and the sum x+y+z is between 10 and 150; * a crosslinking compound (g) or a compound (g) comprising at least two olefinic unsaturations; preferably, in an amount of less from 5% by weight, also preferably from 0.01 to 4% by weight, in particular from 0.02 to 4% by weight or from 0.02 to 2% by weight, in particular from 0.02 to 1% by weight, of monomer (g) relative to the total amount by weight of monomers.

4. Copolymer P according to one of claims 1 to 3 for which the compound (b) is a cyclic thionolactone, preferably a cyclic thionolactone comprising at least 5 to 16 members in the ring, in particular a cyclic thionolactone comprising 5 to 10 members in the ring, preferably a thionolactone chosen from dibenzo[c,e]oxepane-5-thione (DOT, CAS number 4445-34-5), y-thionobutyrolactone (TBL), 6-thionovalerolactone (TVL), co-thionopentadecalactone (TPDL), e-thionocaprolactone (TCL), substituted e-thionocaprolactone (thCL), 3,3-dimethyl-2,3-dihydro-5H-benzo[e][l,4]dioxepine-5-thione (DBT), thionoisochromanone (TIC), 3,6-dimethyl-5-thioxo-1,4-dioxan-2-one (TLD), 5-phenyloxolane-2-thione, 2-benzofuran-l(3H)-thione, l-sulfanylidene-l,3-dihydro-2-benzofuran-5-carbonitrile, 6-nitro-2-benzofuran-l(3H)-thione, 3-ethyl-2-benzofuran-1(3H)-thione, dibenzo[c,e]oxepine-5(7H)-thione and combinations thereof.

5. Copolymer P according to one of claims 1 to 4 which is water-soluble or for which: - the polymerization reaction uses: from 70 mol% to 98 mol% of compound (a), preferably from 70 mol% to 95 mol% of compound (a) or from 75 mol% to 95 mol% of compound (a), more preferably from 80 mol% to 90 mol% of compound (a) or from 85 mol% to 90 mol% of compound (a), or from 2 mol% to 30 mol% of compound (b), preferably from 5 mol% to 30 mol% of compound (b) or from 5 mol% to 25 mol% of compound (b), more preferably from 10 mol% to 20 mol% of compound (b) or from 10 mol% to 15 mol% of compound (b), relative to the molar quantity of compounds (a) and (b); or - the polymerization reaction is carried out at a temperature below 120°C, preferably below 100°C; or - the polymerization reaction is carried out in water, alone or in a mixture with at least one polar, protic solvent, preferably an alcohol, more preferably isopropanol; or for which: - the radical-generating compound is chosen from 4,4'-azobis-4-cyanopentanoic acid (ACPA), hydrogen peroxide, benzoyl peroxide, acetyl peroxide, lauryl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, ammonium persulfate, an alkali metal persulfate (in particular sodium persulfate, potassium persulfate), an azo compound and their combinations or their respective associations with an ion chosen from Fe11, Fe111, Cu1, Cu11 and their combinations.

6. Copolymer P according to one of claims 1 to 5 having a molecular mass by weight Mw, measured by CES, ranging from 800 g / mol to 100,000 g / mol; more preferably from 800 g / mol to 80,000 g / mol or from 800 g / mol to 60,000 g / mol; much more preferably from 1,000 g / mol to 80,000 g / mol or from 1,000 g / mol to 60,000 g / mol; much more preferably from 1,000 g / mol to 30,000 g / mol or from 1,000 g / mol to 20,000 g / mol; even more preferably from 1,000 g / mol to 15,000 g / mol.

7. Method for preparing a copolymer P defined according to one of claims 1 to 6 by a radical ring-opening polymerization reaction in aqueous medium and at a temperature above 50°C: - of at least one anionic compound (a) comprising at least one polymerizable olefinic unsaturation and at least one carboxylic acid function or one of its salts; - of at least one compound (b) chosen from thionolactones, in the presence of at least one radical-generating compound.

8. Dispersing agent comprising at least one copolymer P according to one of claims 1 to 6 and at least one solid or liquid support, preferably water, alone or in combination with at least one other substance, for example at least one surfactant compound

9. A method of dispersing a mineral material comprising the introduction of at least one copolymer P according to one of claims 1 to 6 or at least one dispersing agent according to claim 8 into a composition, preferably into an aqueous composition, comprising particles of a mineral material, preferably a synthetic or naturally occurring mineral material, preferably chosen from alkaline earth metal carbonate, preferably calcium carbonate (natural calcium carbonate or precipitated calcium carbonate), strontium carbonate, magnesium carbonate, barium carbonate and combinations thereof, dolomite, kaolin, calcium dioxide, titanium, talc, lime, calcium sulfate, barium sulfate, tartar and combinations thereof.

10. Method according to one of claims 7 or 9 for which the copolymer P is degradable, preferably degradable in a controlled manner or in a natural manner, more preferably biodegradable, in particular in a basic medium or in an acidic medium.

11. Method for degrading a thioester copolymer P prepared in an aqueous medium, at a temperature above 50°C, by a radical ring-opening polymerization reaction: - of at least one anionic compound (a) comprising at least one polymerizable olefinic unsaturation and at least one carboxylic acid function or one of its salts; - of at least one compound (b) chosen from thionolactones, in the presence of at least one radical-generating compound; comprising treating the copolymer P using at least one basic compound or using at least one acidic compound.

12. Method for preparing a Pd polymer by acid degradation or by basic degradation of a thioester copolymer P prepared in an aqueous medium, at a temperature above 50°C, by a radical ring opening polymerization reaction: - of at least one anionic compound (a) comprising at least one polymerizable olefinic unsaturation and at least one carboxylic acid function or one of its salts; - of at least one compound (b) chosen from thionolactones, in the presence of at least one radical generating compound.

13. Method according to one of claims 11 or 12 for which the degraded polymer, respectively the Pd polymer, has a molecular mass by weight Mw, measured by CES, reduced by 10%, preferably reduced by 25% or reduced by 40%, more preferably reduced by 50% or reduced by 60%, much more preferably reduced by 75% or reduced by 90%, relative to the molecular mass by weight Mw of the copolymer P.