The invention relates to a copolymer obtained by a polymerization reaction using an anionic monomer and two polyethoxylated monomers. The invention also relates to a composition comprising this copolymer as well as a process for its preparation and its use as a superplasticizing agent for a hydraulic binder composition.

The copolymer according to the invention is advantageously used in the technical field of mortars, concretes, plasters or other compositions based on hydraulic compounds or binders, especially cement or plaster. Such compositions can advantageously be used in the fields of construction, public works or the exploitation of hydrocarbons.

Hydraulic binder dispersant compounds are usually used for their ability to modify the rheology of the medium in which they are present, in particular for their ability to control the workability of this medium.

Workability is generally defined as the property of a composition comprising a hydraulic binder, in particular of a slag or of a cement or mortar slurry or even of a concrete, for example a ready-to-use concrete. or precast concrete, to remain workable for as long as possible. Advantageously, controlling the maneuverability makes it possible to transport or move the aqueous composition comprising the hydraulic binder, for example during transport or movement from one tank to another tank. Workability also makes it possible to control the storage conditions of such an aqueous composition. It also makes it possible to be able to pump, or even to pump easily, this composition. Controlling the workability of such a composition therefore makes it possible to improve the conditions of use thereof, in particular to increase its duration of use under satisfactory or effective conditions. Generally, the workability of an aqueous composition comprising a hydraulic binder can be evaluated by measuring the flow time of the hydraulic binder. In particular, the hydraulic binder or the superplasticizer should make it possible to obtain a composition having a controlled and stable viscosity and, preferably, a stable viscosity over a prolonged period.

Preferably, the improvement in the workability of aqueous hydraulic compositions comprising a hydraulic binder should be possible for compositions comprising a small amount of water.

Thus, an important aspect of the invention resides in the provision of an aqueous composition comprising a hydraulic binder having effective workability. Workability control should not lead to impairment of other properties, especially mechanical properties, especially at young ages.

The workability of aqueous compositions comprising a hydraulic binder can be evaluated by measuring the slump, for example according to standard EN 12350-2. Indeed, sag and maneuverability are proportional.

Slump retention is also a property to be controlled for aqueous compositions comprising a hydraulic binder.

These properties are particularly sought after for certain applications, for example when filling formwork with an aqueous composition comprising a hydraulic binder.

Another aspect of the invention relates to obtaining an aqueous formulation comprising a hydraulic binder making it possible to limit or reduce shrinkage during drying.

The improvement in the properties of aqueous formulations comprising a hydraulic binder should be obtained without modifying the setting of the formulation, in particular without delaying this setting.

The aqueous formulations comprising a hydraulic binder should also have a water/hydraulic binder, generally water/cement or W/C, weight ratio that is as low as possible, without however undergoing an alteration of their properties.

An effect also sought for aqueous formulations comprising a hydraulic binder is to make it possible to control the quantity of air occluded in the material resulting from the setting of this formulation, thus making it possible to avoid or reduce the presence of anti-foaming agent within the hydraulic formulation.

In general, the aqueous formulations comprising a hydraulic binder should make it possible to improve the mechanical properties of the materials obtained, in particular their mechanical properties at young ages, properties which can be evaluated by measuring the evolution over time of the resistance to the compression.

Also, the compounds used for the preparation of aqueous formulations comprising a hydraulic binder should be used at reduced doses. They should also have a high or even total compatibility with the other components of the aqueous formulations comprising a hydraulic binder, in particular by being miscible in all proportions with these other components, in order to avoid or limit the risks of segregation of the components of the aqueous formulation. comprising a hydraulic binder.

The increase in the duration of retention of the properties of the aqueous formulations comprising a hydraulic binder must also be sought.

Document WO-2019/020934 describes an aqueous composition comprising a copolymer obtained by a polymerization reaction in the presence of a compound of formula S=C[SC(0)OX] 2which implements a carboxylic and unsaturated anionic monomer and a vinyl hydrophobic monomer. Document WO-2019/020936 also describes an aqueous composition comprising a copolymer obtained by a polymerization reaction in the presence of sodium hypophosphite which uses an anionic carboxylic and unsaturated monomer and a hydrophobic vinyl monomer. Document US -2014/051801 describes a comb polymer prepared in the presence of hydrogen peroxide from maleic acid, allyl ether, (meth)acrylic acid and hydroxyalkyl-(meth)acrylate. These copolymers are used in hydraulic binder compositions.

Dispersing compounds or superplasticizing agents which can be used in aqueous formulations comprising a hydraulic binder are known. However, these compounds do not make it possible to provide a solution to the problems encountered. In particular, these compounds do not make it possible to maintain a good degree of initial fluidity of the aqueous formulations comprising a hydraulic binder in which they are incorporated, while maintaining their workability and without altering their mechanical properties, or causing segregation phenomena.

There is therefore a need to have dispersant or superplasticizer compounds for aqueous formulations comprising a hydraulic binder which make it possible to provide a solution to all or part of the problems of the compounds of the state of the art.

The invention makes it possible to provide a solution to all or part of the problems encountered with the polymers of the state of the art. In particular, the invention makes it possible to obtain copolymers by a particularly effective preparation process, for example as regards the control of the temperature of the polymerization reaction. In particular, it is essential to be able to have preparation processes which make it possible to dispense with maintaining the reaction medium at low temperature used during the polymerization reactions known from the state of the art.

Furthermore, it is also essential to be able to have preparation processes which make it possible to polymerize unsaturated monomers of different molecular masses Mw, for example of molecular mass Mw ranging from 800 to 5000 g/mol or 8000 g/mol measured by CES, in the presence of comonomers comprising vinyl functions.

Similarly, it is essential to be able to implement polymerization reactions making it possible to copolymerize monomers having reactivities limiting or preventing their polymerization during the implementation of the processes of the state of the art.

It is also essential to be able to control these polymerization reactions, in particular to control the proportions of the polymerized comonomers with respect to the proportions of these comonomers introduced during the reaction. Thus, the copolymers prepared may comprise residues of the comonomers in proportions which are identical or close to the proportions of the monomers used, thus ensuring stability of the composition of the copolymer.

It is also essential to be able to prepare terpolymers, or polymers resulting from the reaction of three different monomers, whose properties are improved. In particular, it is important to be able to prepare terpolymers from monomers chosen for the properties that they specifically contribute to the final polymer. In particular, the choice of monomers having different chain lengths makes it possible to confer particular properties on the polymers prepared. This choice is particularly useful when preparing comb terpolymers in which the length of the pendant chains can be modulated. The properties of these polymers, in particular of these terpolymers, can then be controlled in a particularly effective manner.

Thus, the invention provides a copolymer whose polydispersity index Ip , determined by Steric Exclusion Chromatography (CES), is less than 3 , obtained by at least one radical polymerization reaction in water, at a temperature ranging from from 10 to 90°C, and in the presence of:

- at least one radical-generating compound chosen from hydrogen peroxide, ammonium persulphate, an alkali metal persulphate, and their respective mixtures or combinations with an ion chosen from Fe 11 , Fe 111 , Cu 1 , Cu 11 and

- at least one compound chosen from:

(i) a compound comprising phosphorus in oxidation state I;

(ii) a compound of formula (A):

[Chem A]

in which :

- X independently represents H, Na or K,

- R independently represents a Ci-Cs-alkyl group;

(a) acrylic acid alone or in combination with at least one monomer chosen from methacrylic acid, maleic acid, maleic anhydride, itaconic acid, 2-acrylamido-2-methylpropane sulphonic acid, 2-acrylamido-2-methylpropane sulphonic acid, vinylsulfonic, 2-(methacryloyloxy)-ethanesulfonic acid,

2-(methacryloyloxy)ethanesulfonic, sodium methallylsulfonate, styrenesulfonate and their salts;

(b) at least one monomer chosen from:

(bl) a compound of formula (I):

[Chem I]

in which :

- L 1 independently represents an OE group or a combination of OE and OP groups;

- n independently represents an integer or decimal number between 20 and 100;

- OE independently represents an oxy-ethylene group;

- OP independently represents an oxy-propylene group;

(b2) a compound of formula (II):

[Chem II]

in which :

- L 2 independently represents an OE group or a combination of

EO and OP groups;

- m independently represents an integer or decimal number between 20 and 100;

- OE independently represents an oxy-ethylene group;

- OP independently represents an oxy-propylene group;

(c) at least one monomer chosen from:

(cl) a monomer of formula (III):

[Chem III]

in which :

- L 3 independently represents an OE group or a combination of OE and OP groups;

- u independently represents an integer or decimal number between 22 and 150;

- OE independently represents an oxy-ethylene group;

- OP independently represents an oxy-propylene group;

- R 1 independently represents H or CH3;

(c2) a monomer of formula (IV):

[Chem IV]

in which :

- L 4 independently represents an OE group;

- OE independently represents an oxy-ethylene group;

- v independently represents an integer or decimal number between 50 and 150;

(c3) a monomer of formula (V):

[Chem V]

in which :

- L 5 independently represents an OE group;

- OE independently represents an oxy-ethylene group;

- w independently represents an integer or decimal number between 85 and 150; (c4) a compound of formula (VI):

[Chem VI]

in which :

- L 6 independently represents an OE group or a combination of

EO and OP groups;

- 1 independently represents an integer or decimal number between 50 and 150;

- OE independently represents an oxy-ethylene group;

- OP independently represents an oxy-propylene group;

the set of monomers (c) comprising a total number of OE and OP groups which is 1.3 to 2.5 times greater than the total number of OE and OP groups of all the monomers (b).

Thus, essentially according to the invention, the total number by weight of the OE and OP groups of all the monomers (c) is 1.3 to 2.5 times greater than the total number by weight of OE and OP groups of all of the monomers (b). Preferably according to the invention, the monomers (c) comprise a total number of OE and OP groups which is 1.4 to 2.5 times greater than the total number of OE and OP groups of the monomers (b). According to the invention, the copolymer of the invention characterized by such ratios makes it possible to significantly reduce the amount of water in a hydraulic binder composition.

The monomers used during the preparation of the copolymer according to the invention comprise OE groups or else comprise a combination of OE groups and OP groups. According to the invention, OE represents an oxy-ethylene group. It is a group of formula -CH2-CH2O-. According to the invention, OP represents an oxy-propylene group. It is a group of formula -CH 2 CH(CH 3 )O- or else a group of formula -CH(CH3)CH20-.

According to the invention, when the copolymer according to the invention comprises a combination of OE groups and OP groups, the total number of OE groups is strictly greater than the total number of OP groups. Preferably, the proportion by weight of the number of OE groups and the number of OP groups ranges from 98/2 to 52/48, preferably from 85/15 to 55/45, more preferably from 80/20 to 60 /40 or from 75/25 to 65/35, in particular 70/30.

The conditions for preparing the copolymer according to the invention are particularly advantageous. Indeed, these conditions for the preparation of the copolymer according to the invention make it possible to reduce or avoid the formation of homopolymer of the monomer (a). Very advantageously, the copolymer according to the invention does not comprise a homopolymer of monomer (a). Also very advantageously, the copolymer according to the invention does not comprise a copolymer of the monomers (a). According to the invention, these copolymers of monomers (a) are copolymers of several different monomers (a); they do not include monomer (b) or monomer (c). Advantageously, the copolymer according to the invention comprises a reduced amount by weight, low or very low homopolymer of monomer (a) relative to the amount by dry weight of copolymer of monomers (a), (b) and (c). Also advantageously, the copolymer according to the invention comprises a reduced, low or very low quantity by weight of copolymer of monomers (a) relative to the quantity by dry weight of copolymer of monomers (a), (b) and ( vs).

Selon l’invention, l’absence ou la présence d’une quantité réduite, faible ou très faible d’homopolymère du monomère (a) ou de copolymère des monomères (a) permet d’éviter ou de limiter le risque d’inhibition de la cristallisation du béton lorsque le copolymère selon l’invention est utilisé pour ses propriétés plastifiantes au sein d’une formulation de béton. Généralement, un homopolymère du monomère (a) ou un copolymère des monomères (a) possède des propriétés dispersantes de particules de matière minérale et peut donc perturber ou inhiber la cristallisation au sein d’une formulation de béton. Les propriétés de la formulation de béton ou bien du matériau final préparé à partir de la formulation de béton peuvent alors être modifiées ou altérées.

De manière particulièrement avantageuse et particulièrement efficace, l’invention permet de préparer un copolymère à partir des monomères (a), (b) et (c) tout en contrôlant la réaction de polymérisation des monomères (a), (b) et (c). L’invention permet donc d’obtenir une composition aqueuse comprenant une quantité très faible de monomère résiduel (a) par rapport à la quantité en poids sec de copolymère.

Généralement, la présence de monomère résiduel (a) dans un copolymère peut perturber ou inhiber la cristallisation au sein d’une formulation de béton. De manière très avantageuse, le copolymère selon l’invention comprend moins de 2 000 ppm en poids ou moins de 1 500 ppm en poids, de préférence moins de 1 000 ppm en poids ou moins de 500 ppm en poids, en particulier moins de 200 ppm en poids ou moins de 100 ppm en poids, de monomère résiduel (a) par rapport à la quantité en poids sec de copolymère.

La quantité de monomères résiduels est mesurée selon des techniques connues en tant que telles, par exemple par Chromatographie Liquide à Haute Pression (CLHP) ou en anglais « High Performance Liquid Chromatography » (HPLC). Selon cette méthode, les composants constitutifs du mélange sont séparés sur une phase stationnaire et détectés par un détecteur UV. Après étalonnage du détecteur, on peut, par exemple à partir de l’aire du pic correspondant au composé acrylique, obtenir la quantité d’acide (méth)acrylique résiduel.

Lors de la préparation du copolymère selon l’invention, les quantités de monomères (a), (b) et (c) mises en œuvre peuvent varier assez largement. De manière préférée, la réaction de polymérisation met en œuvre, par rapport à la quantité totale de monomères :

- de 5 à 28 % en poids de monomère (a),

- from 68 to 91% by weight of monomer (b) and

- from 4 to 27% by weight of monomer (c).

Also preferably, the polymerization reaction implements, relative to the total amount of monomers:

- from 10 to 27% by weight of monomer (a),

- from 68 to 85% by weight of monomer (b) and

- from 5 to 22% by weight of monomer (c).

Particularly preferably, the copolymer according to the invention comprises, relative to the total amount of monomers:

- from 5 to 28% by weight of monomer (a),

- from 68 to 91% by weight of monomer (b) and

- from 4 to 27% by weight of monomer (c).

Also preferably, the copolymer according to the invention comprises, relative to the total amount of monomers:

- from 10 to 27% by weight of monomer (a),

- from 68 to 85% by weight of monomer (b) and

- from 5 to 22% by weight of monomer (c).

During the preparation of the copolymer according to the invention, the polymerization reaction can implement one or more of the monomers (a), (b) and (c). Preferably according to the invention, the polymerization reaction uses a monomer (a), a monomer (b) and a monomer (c). Also preferably according to the invention, the polymerization reaction uses one monomer (a), one monomer (b) and two monomers (c). Also preferably according to the invention, the polymerization reaction uses one monomer (a), two monomers (b) and one monomer (c).

Preferably according to the invention, the copolymer of the invention is a copolymer obtained by polymerization of at least one monomer (a), at least one monomer (b) chosen from a compound (bl) and a compound ( b2) and at least one monomer (c) chosen from a monomer (c1), a monomer (c2) and a monomer (c4). More preferably according to the invention, the copolymer according to the invention is a copolymer obtained by polymerization of at least one monomer (a), at least one compound (bl) and at least one monomer (c) selected from a monomer (c1) and a monomer (c2).

The invention comprises the implementation of a radical polymerization reaction in water of acrylic acid alone or in combination with at least one other monomer chosen from methacrylic acid, maleic acid, maleic anhydride, itaconic acid, 2- acrylamido-2-methylpropane sulfonic, 2-acrylamido-2-methylpropane sulfonic, vinylsulfonic acid, 2-(methacryloyloxy)-ethanesulfonic acid,

2-(methacryloyloxy)ethanesulfonic acid, sodium methallyl sulfonate, styrene sulfonate and their salts. Preferably, the monomer (a) is acrylic acid alone or alternatively acrylic acid combined with another monomer (a) chosen from methacrylic acid, itaconic acid, 2-acrylamido-2-methylpropane sulphonic acid, 2-acrylamido -2-methylpropane sulphonic acid, vinyl sulphonic acid, 2-(methacryloyloxy)-ethane sulphonic acid, 2-(methacryloyloxy)ethane sulphonic acid, sodium methallyl sulphonate, styrene sulphonate and their salts. More preferably, the monomer (a) is acrylic acid alone or else acrylic acid combined with another monomer (a) chosen from methacrylic acid, maleic acid, maleic anhydride and 2-acrylamido-2-methylpropane sulphonic acid , their salts and their combinations. Much more preferably,

During its implementation according to the invention, the acrylic acid can be used in the form of free acrylic acid or else in the form of an acrylic acid salt, for example a sodium salt. It can also be implemented in the form of a combination of free acrylic acid and an acrylic acid salt, for example a sodium salt.

During the radical polymerization reaction in water, the invention also comprises the use of at least one monomer (b) chosen from a monomer (b1), a monomer (b2) and combinations thereof.

The preferred monomer (b) is monomer (bl). The preferred monomer (bl) is a compound of formula (I) in which n independently represents an integer or decimal number between 10 and 120 or between 20 and 120. The more preferred monomer (bl) is a compound of formula (I) in which n independently represents an integer or decimal number between 25 and 95 or between 40 and 85, in particular between 40 and 60 or between 65 and 85.

A particularly preferred monomer (b1) is the monomer (b1a) of formula (I) in which n represents approximately 53 and L 1 represents OE.

Another particularly preferred monomer (bl) is the monomer (blb) of formula (I) in which n represents approximately 78 and L 1 represents OE.

The preferred monomer (b2) is a compound of formula (II) in which m independently represents an integer or decimal number between 10 and 120 or between 20 and 120. The more preferred monomer (b2) is a compound of formula (II) in which m independently represents an integer or decimal number between 25 and 95 or between 40 and 85, in particular between 40 and 60 or between 65 and 85.

During the radical polymerization reaction in water, the invention also comprises the use of at least one monomer (c) chosen from a monomer (cl), a monomer (c2), a monomer (c3), a monomer (c4) and combinations thereof. Preferred monomers (c) are monomers (c1) and (c2) and their combinations.

The preferred monomer (cl) is a compound of formula (III) in which u independently represents an integer or decimal number between 25 and 170 or between 30 and 160. The more preferred monomer (cl) is a compound of formula (III) where u independently represents an integer or decimal number between 50 and 150.

The preferred monomer (c2) is a compound of formula (IV) in which v independently represents an integer or decimal number between 70 and 140.

The preferred monomer (c3) is a compound of formula (V) in which w independently represents an integer or decimal number between 90 and 140.

The preferred monomer (c4) is a compound of formula (VI) in which t independently represents an integer or decimal number between 70 and 140.

Un monomère (cl) particulièrement préféré est le monomère (cia) de formule (III) dans laquelle u représente environ 112, L3 représente OE et R1 représente H.

Les combinaisons préférées de monomères mises en œuvre lors de la préparation du copolymère selon l’invention sont :

- l’acide acrylique, le monomère (bl) et le monomère (cl), en particulier l’acide acrylique, le monomère (b la) et le monomère (cia) ou bien l’acide acrylique, le monomère (blb) et le monomère (cia) ;

- l’acide acrylique, le monomère (bl) et le monomère (c2) ;

- l’acide acrylique, le monomère (bl), le monomère (cl) et le monomère (c2), en particulier l’acide acrylique, le monomère (bla), le monomère (cia) et le monomère (c2) ou bien l’acide acrylique, le monomère (blb), le monomère (cia) et le monomère (c2).

Même s’il est de préférence préparé à partir des seuls monomères (a), (b) et (c), le copolymère selon l’invention peut également être préparé à partir d’une réaction de polymérisation mettant également en œuvre un monomère non ionique comprenant au moins une insaturation oléfinique polymérisable, de préférence au moins une insaturation éthylénique polymérisable et notamment une fonction vinylique polymérisable, plus préférentiellement un monomère non ionique choisi parmi les esters d’un acide comprenant au moins une fonction acide monocarboxylique, en particulier un ester d’un acide choisi parmi acide acrylique, acide méthacrylique, et leurs mélanges, par exemple hydroxyethylacrylate, hydroxypropylacrylate, hydroxyethylméthacrylate, hydroxypropylméthacrylate.

La préparation du copolymère selon l’invention met en œuvre au moins un composé générateur de radicaux qui est particulier. Il est préférentiellement choisi parmi peroxyde d’hydrogène, persulfate d’ammonium, persulfate de sodium, persulfate de potassium, leurs mélanges ou leurs associations avec un ion choisi parmi Fen, Fem, Cu1, Cu11. Selon l’invention, les ions Fe11, Fe111, Cu1 ou Cun peuvent être mis en œuvre au moyen d’au moins un composé choisi parmi sulfate de fer, sulfate de fer hydraté, sulfate de fer hemi-hydraté, sulfate de fer heptahydraté, carbonate de fer, carbonate de fer hydraté, carbonate de fer hemi-hydraté, chlorure de fer, carbonate de cuivre, carbonate de cuivre hydraté, carbonate de cuivre hemi-hydraté, acétate de cuivre, sulfate de cuivre, sulfate de cuivre pentahydraté, hydroxyde de cuivre, halogénure de cuivre.

Selon l’invention, le composé générateur de radicaux particulier est plus préférentiellement choisi parmi peroxyde d’hydrogène, persulfate d’ammonium, persulfate de sodium, persulfate de potassium, tout particulièrement persulfate de sodium. Selon l’invention, la réaction de polymérisation peut mettre en œuvre un ou plusieurs composés (i) ou bien un ou plusieurs composés (ii). De manière préférée, la réaction de polymérisation met en œuvre un seul composé (i) ou bien un seul composé (ii) ou bien un composé (i) et un composé (ii). De manière préférée selon l’invention, la réaction de polymérisation est mise en œuvre en l’absence de bisulfite de sodium et, plus préférentiellement en l’absence de bisulfite de sodium associé à un composé (ii).

La préparation de la composition aqueuse selon l’invention met en œuvre une réaction de polymérisation radicalaire qui est menée dans l’eau en présence d'au moins un composé (i) comprenant du phosphore au degré d’oxydation I. De manière préférée selon l’invention, la réaction de polymérisation met en œuvre un composé (i) minéral. De manière plus préférée selon l’invention, la réaction de polymérisation met en œuvre un composé (i) choisi parmi l’acide hypophosphoreux (H3PO2), un dérivé de l’acide hypophosphoreux (H3PO2). De manière bien plus préférée selon l’invention, la réaction de polymérisation met en œuvre un composé (i) comprenant au moins un ion hypophosphite (H2PO2 ), plus préférentiellement un composé (i) choisi parmi hypophosphite de sodium (PhPChNa), hypophosphite de potassium (H2PO2K), hypophosphite de calcium ([PbPChkCa) et leurs mélanges. L’hypophosphite de sodium (PbPCLNa) est particulièrement préféré.

La réaction de polymérisation selon l’invention peut également mettre en œuvre au moins un composé (ii) de formule (A) dans laquelle X représente indépendamment H, Na ou K et R représente indépendamment un groupement Ci-Cs-alkyle. De manière préférée selon l’invention, le composé (ii) est un composé de formule (A) dans laquelle R représente un groupement Ci-C3-alkyle, de préférence un groupement méthyle, et X représente H. Le

composé de formule (A) préféré selon l’invention est le dipropionate trithiocarbonate disodique (DPTTC - numéro CAS 86470-33-2).

De manière préférée selon l’invention, le composé (ii) est mis en œuvre en une quantité en poids allant de 0,05 à 5 % en poids, par rapport à la quantité de monomères. De manière également préférée selon l’invention, la réaction de polymérisation met en œuvre le composé (ii) de formule (A) en une quantité de 0,05 à 4 % en poids, de 0,05 à 3 % en poids, de 0,05 à 2 % en poids, de 0,5 à 4 % en poids, de 0,5 à 3 % en poids, de 0,5 à 2 % en poids, de 1 à 4 % en poids, de 1 à 3 % en poids, de 1 à 2 % en poids par rapport à la quantité de monomères.

Le copolymère selon l’invention possède un indice de polymolécularité Ip inférieur à 3. De manière préférée selon l’invention, l’indice de polymolécularité Ip va de 1,5 à 3, plus préférentiellement de 1,5 à 2,8, bien plus préférentiellement de 1,5 à 2,5.

Le copolymère selon l’invention est obtenu par au moins une réaction de polymérisation radicalaire dans l’eau et à une température allant de 10 à 90°C, de préférence allant de 30 à 85°C, plus préférentiellement à une température allant de 40 à 75°C ou de 50 à 70°C, bien plus préférentiellement de 50 à 68°C ou de 50 à 65°C.

De manière plus préférée, une seule réaction de polymérisation radicalaire est mise en œuvre.

Le copolymère selon l’invention peut également être caractérisé par sa masse moléculaire en poids (Mw). De manière préférée, il possède une masse moléculaire en poids allant de 8 000 g/mol à 200 000 g/mol ou de 10 000 g/mol à 200 000 g/mol ou encore de 12 000 g/mol à 200 000 g/mol. De manière plus préférée, il possède une masse moléculaire en poids allant de 15 000 g/mol à 150 000 g/mol ou de 15 000 g/mol à 120 000 g/mol ou encore de 15 000 g/mol à 90 000 g/mol ou de 15 000 g/mol à 50 000 g/mol.

Selon l’invention, le poids moléculaire et l’indice de polymolécularité des copolymères est déterminé par Chromatographie d'Exclusion Stérique (CES) ou en anglais « Steric Exclusion Chromatography » (SEC). Cette technique met en œuvre un appareil de

Waters brand liquid chromatography equipped with a detector. This detector is a Waters brand refractometric concentration detector. This liquid chromatography apparatus is equipped with a steric exclusion column in order to separate the different molecular weights of the copolymers studied. The liquid elution phase is an aqueous phase adjusted to pH 9.00 using 1 N sodium hydroxide containing 0.05 M NaHCCL, 0.1 M NaNCh, 0.02 M triethanolamine and 0.03% NaN3 .

According to a first step, the copolymer solution is diluted to 0.9% dryness in the solubilization solvent of the CES, which corresponds to the liquid phase of elution of the CES to which is added 0.04% of dimethylformamide which plays the role of flow marker or internal standard. Then, it is filtered at 0.2 μm. 100 μL are then injected into the chromatography apparatus (eluent: an aqueous phase adjusted to pH 9.00 with IN sodium hydroxide containing 0.05 M NaHCCL, 0.1 M NaNCh, 0.02 M 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 also comprises an oven which itself comprises in series the following column system: a guard column of the Guard Column Ultrahydrogel Waters type 6 cm in length and 40 mm in internal diameter and a linear column of the Ultrahydrogel Waters type of 30 cm in length and 7.8 mm in internal diameter. The detection system consists of a refractometric detector of the RI Waters 410 type. The oven is brought to a temperature of 60° C. and the refractometer is brought to a temperature of 45° C.

The molecular weights are evaluated by dynamic light scattering detection using a Viscotek Dual 270 detector by which the molecular weight is determined from the hydrodynamic volume of the copolymer.

The copolymer according to the invention is obtained by at least one radical polymerization reaction in water. An aqueous composition comprising the copolymer according to the invention is then obtained. The water can be separated in order to obtain the copolymer as such, for example in powder form. The invention therefore also provides an aqueous composition comprising water and at least one copolymer according to the invention.

The particular, advantageous or preferred characteristics of the copolymer according to the invention define aqueous compositions according to the invention which are also particular, advantageous or preferred.

The copolymer and the aqueous composition according to the invention have particularly advantageous properties in numerous technical fields. Depending on the technical field in which their properties are implemented, the copolymer or the aqueous composition according to the invention can take different forms. They can therefore be used directly or else be used in combination with other ingredients. They can be implemented in different formulations. Preferably, these formulations can be hydraulic binder formulations.

Thus, the invention also relates to a formulation (F1) comprising:

- at least one copolymer according to the invention;

- at least one hydraulic binder; Most often is "possibly"

- some water ; Most often is "possibly"

- at least one aggregate; Most often is "possibly"

- at least one adjuvant.

The invention also relates to a formulation (F2) comprising:

- at least one aqueous composition according to the invention;

- at least one hydraulic binder;

- some water ; Most often is "possibly"

- at least one aggregate; Most often is "possibly"

- at least one adjuvant.

Preferably, the formulations (F1) and (F2) according to the invention comprise:

- from 0.01 to 5% by dry weight of copolymer, respectively in the form of at least one aqueous composition according to the invention or in the form of at least one copolymer according to the invention as such;

- From 95 to 99.9% by dry weight of at least one hydraulic binder.

De manière plus préférée, les formulations (Fl) et (F2) selon l’invention comprennent : - de 0,01 à 4 % en poids sec ou de 0,01 à 3 % en poids sec de copolymère, respectivement sous la forme d’au moins une composition aqueuse selon l’invention ou sous la forme d’au moins un copolymère selon l’invention en tant que tel ;

- de 96 à 99,9 % en poids sec ou de 97 à 99,9 % en poids sec d’au moins un liant hydraulique.

De manière également plus préférée, les formulations (Fl) et (F2) selon l’invention comprennent :

- de 0,03 à 5 % en poids sec ou de 0,03 à 4 % en poids sec ou de 0,03 à 3 % en poids sec de copolymère, respectivement sous la forme d’au moins une composition aqueuse selon l’invention ou sous la forme d’au moins un copolymère selon l’invention en tant que tel ;

- de 95 à 99,7 % en poids sec ou de 96 à 99,7 % en poids sec de 97 à 99,7 % en poids sec d’au moins un liant hydraulique.

De manière également plus préférée, les formulations (Fl) et (F2) selon l’invention comprennent :

- de 0,05 à 5 % en poids sec ou de 0,05 à 4 % en poids sec ou de 0,05 à 3 % en poids sec ou de 0,05 à 2 % en poids sec ou de 0,05 à 1,5 % en poids sec de copolymère, respectivement sous la forme d’au moins une composition aqueuse selon l’invention ou sous la forme d’au moins un copolymère selon l’invention en tant que tel ;

- de 95 à 99,5 % en poids sec ou de 96 à 99,5 % en poids sec ou de 97 à 99,5 % en poids sec ou de 98 à 99,5 % en poids sec ou de 98,5 à 99,5 % en poids sec, d’au moins un liant hydraulique.

De manière également préférée, les formulations (Fl) et (F2) selon l’invention comprennent de l’eau en une quantité en poids relative à la quantité en poids de liant hydraulique inférieure à 0,7, inférieure à 0,65 ou inférieure à 0,6, de préférence inférieure à 0,5 ou inférieure à 0,4 ou encore inférieure à 0,3 ou inférieure à 0,2. Des gammes préférées de quantité d’eau en poids par rapport à la quantité en poids de liant hydraulique dans les formulations (Fl) et (F2) vont de 0,2 à 0,65 ou de 0,2 à 0,6 ou de 0,2 à 0,5 ou de 0,3 à 0,65 ou de 0,3 à 0,6 ou de 0,3 à 0,5.

Selon l’invention, le liant hydraulique ou hydrolithe peut être choisi parmi ciment, mortier, plâtre, coulis, béton.

Le ciment peut être choisi parmi ciment Portland, ciment Portland blanc, ciment artificiel, ciment de haut fourneau, ciment à haute résistance, ciment à l’alumine, ciment rapide, ciment au phosphate de magnésium, ciment à base de produits d’incinération, ciment de cendres volantes et leurs mélanges.

D’autres liants hydrauliques peuvent être choisis parmi liants hydrauliques latents, liants pouzzolaniques, cendres, scories, mâchefer.

Le plâtre peut être choisi parmi gypse, sulfate de calcium dihydraté, sulfate de calcium, hémihydrate de sulfate de calcium, anhydride de sulfate de calcium et leurs mélanges. L’agrégat peut être choisi parmi sable, agrégat grossier, gravier, pierre concassée, scories, agrégat recyclé.

Généralement, selon leur granulométrie, on classe les granulats en plusieurs catégories connues en tant que telles par l'homme du métier, par exemple selon la norme française XP P 18-540. Selon cette norme, définissant notamment les valeurs d et D, les familles de granulats comprennent :

- les fillers 0/D pour lesquels D < 2 mm avec au moins 70 % de passant à 0,063 mm,

- les sablons 0/D pour lesquels D < 1 mm avec moins de 70 % de passant à 0,063 mm,

- les sables 0/D pour lesquels 1< D < 6,3 mm,

- les graves 0/D pour lesquels D > 6,3 mm,

- les gravillons d/D pour lesquels d > 1 mm et D < 125 mm,

- les ballasts d/D pour lesquels d > 25 mm et D < 50 mm.

Des exemples de fillers sont des fumées de silice ou additions siliceuses, ou des additions calcaires comme du carbonate de calcium.

Selon l’invention, l’adjuvant des formulations (Fl) ou (F2) peut être choisi parmi un agent anti-mousse, un agent plastifiant ou superplastifiant, un agent d’amélioration de l’ouvrabilité, un agent réducteur d’affaissement, un agent réducteur d’entraînement de l’air, un agent colorant, un pigment, un agent réducteur d’eau, un agent retardateur de prise, un agent de contrôle de l’hygroscopie, un agent anti-corrosion, un agent anti-retrait, un agent inhibiteur de réactions silico-alcalines, un agent hydrofuge, un agent moussant.

Les propriétés particulières de la composition aqueuse selon l’invention ou du copolymère selon l’invention permettent de les utiliser dans de nombreux domaines techniques, notamment pour leurs propriétés de contrôle ou de régulation de la rhéologie.

Ainsi, l’invention fournit une méthode de modification de la rhéologie d’une formulation hydraulique comprenant l’addition d’au moins une composition aqueuse selon l’invention ou d’au moins un copolymère selon l’invention dans la formulation hydraulique comprenant de l’eau et un liant hydraulique.

Les propriétés de la composition selon l’invention et du copolymère sont particulièrement utiles dans le domaine des formulations hydrauliques.

L’invention fournit donc une méthode de réduction d’eau d’une formulation hydraulique comprenant l’addition d’au moins une composition aqueuse selon l’invention ou d’au moins un copolymère selon l’invention dans une formulation hydraulique. Selon l’invention, la méthode de réduction d’eau est déterminée selon la norme ADJUVANT NF EN 934-2.

De manière préférée pour la méthode de réduction d’eau d’une formulation hydraulique selon l’invention, la formulation hydraulique est choisie parmi une formulation hydraulique (Fl) et une formulation hydraulique (F2). Selon l’invention, la réduction d’eau de la formulation hydraulique est déterminée par rapport à la quantité d’eau d’une formulation hydraulique ne comprenant pas de copolymère. De manière préférée selon l’invention, la méthode de réduction d’eau selon l’invention permet de réduire la quantité en poids d’eau dans la formulation hydraulique d’au moins 15 %, de préférence d’au moins 20 % ou d’au moins 25 %, plus préférentiellement d’au moins 30 % par rapport à la quantité d’eau d’une formulation hydraulique ne comprenant pas de copolymère.

Les caractéristiques particulières, avantageuses ou préférées des formulations hydrauliques (Fl) et (F2) selon l’invention définissent des méthodes de réduction d’eau d’une formulation hydraulique selon l’invention qui sont également particulières, avantageuses ou préférées.

Les exemples qui suivent permettent d’illustrer les différents aspects de l’invention.

Exemple 1 : préparation de copolymères selon l’invention et d’un copolymère comparatif

Exemple 1.1 : copolymère (PI) selon l’invention

In a stirred reactor, water (90 g), a monomer (bla) of molecular mass 2400 g/mol in solution at 60% by weight in water (440.8 g), a comonomer (cia ) of molecular weight 5000 g/mol in 50% solution in water (80 g) and hydrated sodium hypophosphite (1.4 g). The reactor is heated to 65 ± 2°C. Then, for 1 hour, a mixture of water (34.2 g) and acrylic acid (57.44 g), a mixture of water (34.2 g) and hydrated sodium hypophosphite (12.57 g), as well as a mixture of water (13.7 g) and sodium persulfate (5.6 g). The reactor is then maintained at a temperature of 65±2° C. for 1 hour.

The product is cooled and then neutralized by adding a 50% by weight aqueous sodium hydroxide solution (63 g). The aqueous polymeric solution comprises less than 3 ppm of dry residual acrylic acid relative to the total quantity of dry copolymer.

A copolymer (PI) comprising 15.9% by weight of acrylic acid, 73.1% by weight of monomer (bla) and 11.0% by weight of monomer (cia) is obtained. Its molecular mass Mw is 35,000 g/mol and its polydispersity index Ip is 1.9.

Example 1.2: copolymer (P2) according to the invention

In a stirred reactor, water (90 g), a monomer (bla) of molecular mass 2400 g/mol in solution at 60% by weight in water (420.8 g) and hypophosphite of hydrated sodium (1.4 g). The reactor is heated to 65 ± 2°C.

Then, for 1 hour, a mixture of water (34.2 g), acrylic acid (57.44 g) and comonomer (cia) of molecular weight 5000 g/mol is injected into the reactor in parallel. 50% solution in water (100 g), a mixture of water (34.2 g) and hydrated sodium hypophosphite (12.57 g), as well as a mixture of water (13.7 g) and sodium persulfate (5.6 g). The reactor is then maintained at a temperature of 65±2° C. for 1 hour.

The product is cooled and then neutralized by adding a 50% by mass aqueous sodium hydroxide solution (62.2 g). The aqueous polymeric solution comprises less than 3 ppm of dry residual acrylic acid relative to the total quantity of dry copolymer.

A copolymer (P2) comprising 16.0% by weight of acrylic acid, 70.1% by weight of monomer (bla) and 13.9% by weight of monomer (cia) is obtained. Its molecular weight Mw is 29,000 g/mol and its polydispersity index Ip is 1.5.

Example 1.3: copolymer (P3) according to the invention

In a stirred reactor, water (90 g), a monomer (bla) of molecular mass 2400 g/mol in solution at 60% by mass in water (400.8 g) and hypophosphite of hydrated sodium (1.4 g). The reactor is heated to 65 ± 2°C.

Then, for 1 hour, a mixture of water (34.2 g), acrylic acid (57.44 g) and comonomer (cia) of molecular weight 5000 g/mol is injected into the reactor in parallel. 50% solution in water (120 g), a mixture of water (34.2 g) and hydrated sodium hypophosphite (12.57 g), as well as a mixture of water (13.7 g) and sodium persulfate (5.6 g). The reactor is then maintained at a temperature of 65±2° C. for 1 hour.

The product is cooled and then neutralized by adding an aqueous solution of sodium hydroxide at 50% by mass (62.0 g). The aqueous polymeric solution comprises less than 3 ppm of dry residual acrylic acid relative to the total quantity of dry copolymer.

A copolymer (P3) comprising 16.0% by weight of acrylic acid, 67.2% by weight of monomer (bla) and 16.8% by weight of monomer (cia) is obtained. Its molecular mass Mw is 31,000 g/mol and its polydispersity index Ip is 1.3.

Example 1.4: copolymer (P4) according to the invention

In a stirred reactor, water (30 g), a monomer (bla) of molecular mass 2400 g/mol in solution at 60% by mass in water (440.8 g) and a comonomer (cia ) of molecular mass 5000 g/mol in 50% solution in water (80 g) and DPTTC in 20% mass solution in water (2.54 g). The reactor is heated to 65±2° C. and hydrogen peroxide in aqueous solution at 35% by mass (5.6 g) is introduced.

Then, during lh15, a mixture of water (34.2 g) and acrylic acid (57.44 g), a mixture of water (76 g) and DPTTC in solution at 20% by mass in water (10.15 g) and a mixture of water (55 g) and ammonium persulfate (2.26 g) in lh40 for the latter.

The reactor is maintained at a temperature of 65±2° C. for 1 hour.

The product is cooled and then neutralized by adding an aqueous solution of sodium hydroxide at 50% by weight (63.5 g). The aqueous polymeric solution comprises less than 15 ppm of dry residual acrylic acid relative to the total quantity of dry copolymer. A copolymer (P4) comprising 15.9% by weight of acrylic acid, 73.1% by

weight of monomer (b la) and 11.0% by weight of monomer (cia). Its molecular weight Mw is 110,000 g/mol and its polydispersity index Ip is 1.4.

Exemple 1.5 : copolymère (P5) selon l’invention

Dans un réacteur agité, on introduit de l’eau (110 g), un monomère (blb) de masse moléculaire 3 500 g/mol en solution à 60 % massique dans l’eau (493,3 g), un comonomère (cia) de masse moléculaire 5 000 g/mol en solution à 50 % dans l’eau (61,16 g) et de l’hypophosphite de sodium hydraté (1,06 g). On chauffe le réacteur à 65 ± 2°C.

Puis, durant 1 h, on injecte en parallèle dans le réacteur un mélange d’eau (35,0 g) et d’acide acrylique (44,08 g), un mélange d’eau (40,0 g) et d’hypophosphite de sodium hydraté (9,52 g), ainsi qu’un mélange d’eau (40,0 g) et de persulfate de sodium (4,25 g). Le réacteur est ensuite maintenu en température à 65 ± 2°C durant 1 h.

Le produit est refroidi puis neutralisé par ajout d’une solution aqueuse de soude à 50 % massique (46,3 g). La solution polymérique aqueuse comprend moins de 10 ppm d’acide acrylique résiduel sec par rapport à la quantité totale de copolymère sec.

On obtient un copolymère (P5) comprenant 11,9 % en poids d’acide acrylique, 79,9 % en poids de monomère (blb) et 8,2 % en poids de monomère (cia). Sa masse moléculaire Mw est de 39 000 g/mol et son indice de polymolécularité Ip est de 1,6.

Exemple 2 : évaluation du pouvoir réducteur d’eau dans un mortier

On prépare des formulations de mortier dont la composition est présentée dans le tableau 1 selon la procédure :

incorporation de l’adjuvant et de l’eau dans le bol d’un malaxeur automatique Perrier pour ciments et mortiers normalisés,

incorporation of all the fines (cement and/or hydraulic binders), mixing at slow speed of 140 rpm,

incorporation of the sand after 30 s,

mixing at slow speed of 140 rpm for 60 s,

stop for 30 s and clean the walls of the bowl,

mixing at slow speed of 140 rpm for 90 s.

In a similar manner, a comparative formulation (FC) of mortar not comprising any copolymer is prepared.

The water-reducing power of the copolymers according to the invention is evaluated from mortar formulations.

The workability T0 of the mortars formulated with the copolymers according to the invention was evaluated by measuring the spreading diameter (slump flow in English) according to standard EN 12350-2 adapted to the mortar (Abrams mini-cone).

To perform the spreading, the cone filled with formulated mortar is lifted perpendicular to a horizontal plate while performing a quarter turn. The spread is measured after 5 minutes along two diameters at 90° with a ruler. The result of the spreading measurement is the average of the 2 values ​​at ± 1 mm.

The tests are carried out at 20°C. The dosage of adjuvant is determined so as to reach a target spread of 220 mm ± 5 mm. The dosage is expressed in % by dry weight relative to the weight of the hydraulic binder or of the mixture of hydraulic binders. The results are shown in Table 1.

[Table 1]

The implementation of the copolymers according to the invention makes it possible to reduce the quantity of water by 36% in the hydraulic formulations, while maintaining an initial fluidity

(workability) similar to that of the comparative formulation comprising no copolymer.

The copolymers according to the invention can therefore be qualified as high water-reducing agents according to the ADJUVANT standard NF EN 934-2. Indeed, they allow a reduction of water for the admixed mortar of at least 12% compared to the control mortar.

The implementation of the copolymers according to the invention would make it possible to obtain similar results within admixed concrete by reduction of at least 12% of the quantity of water compared to a control concrete not comprising copolymer according to the invention.

CLAIMS

1. Copolymer whose polydispersity index Ip , determined by Steric Exclusion Chromatography (CES), is less than 3 , obtained by at least one radical polymerization reaction in water, at a temperature ranging from 10 to 90° C, and in the presence:

- at least one radical-generating compound chosen from:

hydrogen peroxide, ammonium persulfate, an alkali metal persulfate, and their respective mixtures or combinations with an ion selected from Fe 11 , Fe 111 , Cu 1 , Cu 11 and

- at least one compound chosen from:

(i) a compound comprising phosphorus in oxidation state I;

(ii) a compound of formula (A):

[Chem A]

in which :

- X independently represents H, Na or K,

- R independently represents a Ci-Cs-alkyl group;

(a) acrylic acid alone or in combination with at least one monomer chosen from methacrylic acid, maleic acid, maleic anhydride, itaconic acid, 2-acrylamido-2-methylpropane sulphonic acid, 2-acrylamido-2-methylpropane sulphonic acid, vinylsulfonic acid, 2-(methacryloyloxy)ethanesulfonic acid, 2-(methacryloyloxy)ethanesulfonic acid, sodium methallylsulfonate, styrenesulfonate and their salts;

(b) at least one monomer chosen from:

(bl) a compound of formula (I):

[Chem I]

in which :

- L 1 independently represents an OE group or a combination of OE and OP groups;

- n independently represents an integer or decimal number between 20 and 100;

- OE independently represents an oxy-ethylene group;

- OP independently represents an oxy-propylene group;

(b2) a compound of formula (II):

[Chem II]

in which :

- L 2 independently represents an OE group or a combination of OE and OP groups;

- m independently represents an integer or decimal number between 20 and 100;

- OE independently represents an oxy-ethylene group;

- OP independently represents an oxy-propylene group;

(c) at least one monomer chosen from:

(cl) a monomer of formula (III):

[Chem III]

in which :

- L 3 independently represents an OE group or a combination of OE and OP groups;

- u independently represents an integer or decimal number between 22 and 150;

- OE independently represents an oxy-ethylene group;

- OP independently represents an oxy-propylene group;

- R 1 independently represents H or ϋ¾;

(c2) a monomer of formula (IV):

[Chem IV]

in which :

- L 4 independently represents an OE group;

- OE independently represents an oxy-ethylene group;

- v independently represents an integer or decimal number between 50 and 150;

(c3) a monomer of formula (V):

[Chem V]

in which :

- L 5 independently represents an OE group;

- OE independently represents an oxy-ethylene group;

- w independently represents an integer or decimal number between 85 and 150;

(c4) a compound of formula (VI):

[Chem VI]

in which :

- L 6 independently represents an OE group or a combination of OE and OP groups;

- 1 independently represents an integer or decimal number between 50 and 150;

- OE independently represents an oxy-ethylene group;

- OP independently represents an oxy-propylene group;

the set of monomers (c) comprising a total number of OE and OP groups which is 1.3 to 2.5 times greater than the total number of OE and OP groups of all the monomers (b).

2. Copolymer according to claim 1

- not comprising any homopolymer of monomer (a) or comprising a reduced, low or very low quantity by weight of homopolymer of monomer (a) relative to the quantity by dry weight of copolymer of monomers (a), (b ) etc) ; or

- not comprising any copolymer of monomers (a) or comprising a reduced, low or very low quantity by weight of copolymer of monomers (a) relative to the quantity by dry weight of copolymer of monomers (a), (b) and (vs).

3. Copolymer according to one of claims 1 and 2 for which:

- the monomer (a) is acrylic acid alone or else acrylic acid combined with another monomer (a) chosen from methacrylic acid, maleic acid, maleic anhydride and 2-acrylamido-2-methylpropane sulphonic acid, their salts and their combinations; Where

- the monomer (b) is chosen from a monomer (b1), a monomer (b2) and combinations thereof; Where

- the monomer (bl) is a compound of formula (I) in which n independently represents an integer or decimal number between 30 and 90 or between 40 and 90 or else between 30 and 85 or between 40 and 65, in particular between 40 and 60 or between 65 and 85; Where

- the monomer (b2) is a compound of formula (II) in which m independently represents an integer or decimal number between 30 and 90 or between 40 and 90 or else between 30 and 85 or between 40 and 65, in particular between 40 and 60 or between 65 and 85; Where

- the monomer (c) is chosen from the monomers (cl) and (c2) and their combinations; Where

- the monomer (cl) is a compound of formula (III) in which u independently represents an integer or decimal number between 25 and 170 or between 30 and 160 or else between 50 and 150; Where

- the monomer (c2) is a compound of formula (IV) in which v independently represents an integer or decimal number between 70 and 140; Where

- the monomer (c3) is a compound of formula (V) in which w independently represents an integer or decimal number between 90 and 140; Where

- the monomer (c4) is a compound of formula (VI) in which t independently represents an integer or decimal number between 70 and 140.

4. Copolymer according to one of claims 1 to 3 for which the polymerization reaction implements, relative to the total amount of monomers:

- from 5 to 28% by weight of monomer (a),

- from 68 to 91% by weight of monomer (b) and

- from 4 to 27% by weight of monomer (c).

5. Copolymer according to one of claims 1 to 3 comprising, relative to the total amount of monomers:

- from 5 to 28% by weight of monomer (a),

- from 68 to 91% by weight of monomer (b) and

- from 4 to 27% by weight of monomer (c).

6. Copolymer according to one of claims 1 to 5 comprising less than 2000 ppm by weight or less than 1500 ppm by weight, preferably less than 1000 ppm by weight or less than 500 ppm by weight, in particular less than 200 ppm by weight or less than 100 ppm by weight, of residual monomer (a) with respect to the quantity by dry weight of copolymer.

7. Copolymer according to one of claims 1 to 6 for which:

- the polymerization reaction uses a mineral compound (i) or hypophosphorous acid (H3PO2) or else a derivative of hypophosphorous acid (H3PO2), preferably a compound (i) comprising at least one hypophosphite ion ( H2PO2), more preferably a compound (i) chosen from sodium hypophosphite (PhPC Na), potassium hypophosphite (H2PO2K), calcium hypophosphite ([H 2 P0 2 ] 2 Ca) and

mixtures thereof; or

- the polymerization reaction uses a compound (ii) of formula (A) in which X represents H and R represents a methyl group.

8. Copolymer according to one of claims 1 to 7 for which the monomers (c) comprise a total number of OE and OP groups which is 1.4 to 2.5 times greater than the total number of OE and OP groups of the monomers ( b); or for which the number of OE groups is strictly greater than the total number of OP groups.

9. Copolymer according to one of claims 1 to 8 for which the polymerization reaction is carried out at a temperature ranging from 30 to 85°C, preferably from 40 to 75°C or from 50 to 70°C, more preferably from 50 to 68°C or from 50 to 65°C.

10. Copolymer according to one of claims 1 to 9 for which the polymerization reaction is carried out in the presence of 0.05 to 5% by weight, relative to the amount of monomers, of at least one compound (ii ) of formula (A); or is implemented in the presence of a compound (i) and a compound (ii).

11. Aqueous composition comprising water and at least one copolymer according to one of claims 1 to 10.

12. Formulation (F1) comprising:

- at least one copolymer according to one of claims 1 and 10;

- at least one hydraulic binder; Most often is "possibly"

- some water ; Most often is "possibly"

- at least one aggregate; Most often is "possibly"

- at least one adjuvant.

13. Formulation (F2) comprising:

- at least one aqueous composition according to claim 11;

- at least one hydraulic binder;

- some water ; Most often is "possibly"

- at least one aggregate; Most often is "possibly"

- at least one adjuvant.

14. Formulation according to one of claims 12 or 13 comprising:

- from 0.01 to 5% by dry weight of copolymer, respectively in the form of at least one aqueous composition according to one of claims 11 or in the form of at least one copolymer according to one of claims 1 to 10 as such;

- From 95 to 99.9% by dry weight of at least one hydraulic binder.

15. Formulation according to one of claims 12 to 14 comprising water in an amount by weight relative to the amount by weight of hydraulic binder of less than 0.7, less than 0.65 or less than 0.6, of preferably less than 0.5 or less than 0.4 or even less than 0.3 or less than 0.2 or even ranging from 0.2 to 0.65 or from 0.2 to 0.6 or from 0.2 to 0.5 or from 0.3 to 0.65 or from 0.3 to 0.6 or from 0.3 to 0.5.

16. Method for modifying the rheology of a hydraulic formulation comprising the addition of at least one aqueous composition according to claim 11 or of at least one copolymer according to one of claims 1 to 10 in the hydraulic formulation.

17. Method for reducing water from a hydraulic formulation comprising the addition of at least one aqueous composition according to claim 11 or of at least one copolymer according to one of claims 1 to 10 in the hydraulic formulation.

18. Water reduction method according to claim 17 for which the quantity by weight of water in the hydraulic formulation is reduced by at least 15%, preferably by at least 20% or by at least 25%, more preferably at least 30% relative to the amount of water in a hydraulic formulation not comprising a copolymer.