Method for modifying the properties of an aqueous suspension

1. A method for modifying the properties of a composition of a suspension of dispersed solid or liquid particles in an aqueous medium, comprising adding a polymer to the composition, increasing the viscosity of the composition and promoting the suspending of the dispersed solid or liquid particles in the aqueous medium,

wherein said polymer is prepared by inverse emulsion polymerization of monomers A b , comprising a betaine group, and of nonionic monomers B a included in an aqueous phase dispersed in the form of droplets in a hydrophobic external phase,

wherein the molar ratio of the monomers A b to the monomers B a is from about 4/96 to about 40/60, the polymer exhibits an intrinsic viscosity of greater than 600 milliLiters/gram, the intrinsic viscosity being measured by dissolving the polymer in a 20% by weight aqueous NaCl solution,

wherein the composition exhibits an ionic strength of at least 0.7 mol/l, and

wherein the dispersed particles comprise solid particles comprising sand, density-modifying particles, excavation products, debris, or polymeric particles, and/or liquid particles comprising synthetic oils, oils of vegetable origin, or oils of mineral origin,

wherein the composition of the suspension of dispersed solid or liquid particles in the aqueous medium is at a temperature of greater than or equal to 70° C. wherein the suspension comprises greater than or equal to 0.5% of the polymer; and

wherein the aqueous medium is a saline composition that comprises at least 35 g/l of a salt.

2. The method according to claim 1 , wherein the monomer A b comprises one or more monomers selected from:

alkylsulphonates or -phosphonates of dialkylammonioalkyl acrylates or methacrylates, -acrylamides or -methacrylamides,

heterocyclic betaine monomers,

alkylsulphonates or -phosphonates of dialkylammonioalkylallylics,

alkylsulphonates or -phosphonates of dialkylammonioalkylstyrenes,

betaines resulting from ethylenically unsaturated anhydrides and dienes, and phosphobetaines.

3. The method according to claim 1 , wherein the monomer A b comprises one or more monomers selected from sulphohydroxypropyldiethylammonioethyl methacrylate, sulphobetaines derived from piperazine, 2-vinyl-1-(3-sulphopropyl)pyridinium betaine (2SPV or “SPV”), 4-vinyl-1-(3-sulphopropyl)pyridinium betaine (4SPV), 1-vinyl-3-(3-sulphopropyl)imidazolium betaine, sulphopropylmethyldiallylammonium betaine, alkylsulphonates or phosphonates of dialkylammonioalkylstyrenes, betaines derived from ethylenically unsaturated anhydrides and dienes, and phosphobetaines.

4. The method according to claim 1 , wherein the monomer A b comprises one or more monomers selected from monomers according to the formula:

or the formula:

in which:

R 1 is hydrogen or methyl,

R 2 and R 3 , which are identical or different, are hydrogen or alkyl having from 1 to 6 carbon atoms,

Y 1 is a divalent group of formula —O— or NR 2 ,

Z − is SO 3 − ,

m is 2 or 3, and

n is 1-6.

5. The method according claim 1 , wherein the monomer A b comprises one or more monomers selected from:

sulphopropyldimethylammonioethyl methacrylate (SPE),

sulphoethyldimethylammonioethyl methacrylate,

sulphobutyldimethylammonioethyl methacrylate,

sulphohydroxypropyldimethylammonioethyl methacrylate (SHPE),

sulphopropyldimethylammoniopropylacrylamide,

sulphopropyldimethylammoniopropylmethacrylamide (SPP),

sulphohydroxypropyldimethylammoniopropylmethacrylamide (SHPP),

sulphopropyldiethylammonioethyl methacrylate,

2-vinyl-1-(3-sulphopropyl)pyridinium betaine,

4-vinyl-1-(3-sulphopropyl)pyridinium betaine,

sulphopropyldimethylammonioethyl methacrylate,

1-vinyl-3-(3-sulphopropyl)imidazolium betaine, and

sulphopropylmethyldiallylammonium betaine.

6. The method according to claim 1 , wherein the monomer A b comprises one or more monomers according to the following formulae:

7. The method according to claim 1 , wherein, during the polymerization, the monomer B a is a hydrophilic monomer included in the disperse aqueous phase.

8. The method according to claim 1 , wherein the nonionic monomer B a comprises one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, glycerol monomethacrylate, acrylamide (AM), methacrylamide, N-methylolacrylamide, dimethylacrylamide, dimethylmethacrylamide, poly(ethylene and/or propylene oxide), if appropriate random or in the block form, α-methacrylates, vinyl alcohol or vinylpyrrolidone.

9. The method according to claim 1 , wherein the hydrophilic nonionic monomer B a comprises acrylamide (AM).

10. The method according to claim 1 , wherein the monomer A b is sulphopropyldimethylammonioethyl methacrylate (SPE) or sulphopropyldimethylammoniopropylmethacrylamide (SPP).

11. The method according to claim 1 , wherein the hydrophobic external phase is based on a hydrocarbon.

12. The method according to claim 1 , wherein the polymerization comprises the following stages: a1): preparation of the inverse emulsion, and a2): polymerization.

13. The method according to claim 12 , wherein stage a1) is carried out by emulsification of a mixture comprising the aqueous phase comprising the monomers, the external phase and at least one emulsifying agent.

14. The method according to claim 12 , wherein polymerization is carried out by bringing together monomers A b and optionally monomers B a with a compound which generates free radicals.

15. The method according to claim 12 , wherein polymerization is carried out at a temperature between ambient temperature and 75° C.

16. The method according to claim 1 , wherein the polymer is in the form of an aqueous composition comprising the inverse emulsion with an aqueous phase comprising the polymer dispersed in the form of droplets in a hydrophobic external phase and other ingredients chosen from a surfactant, an organic salt, an inorganic salt, a detergent and a thickener.

17. The method according to claim 1 , wherein the saline composition is based on seawater or on a brine.

18. The method according to claim 16 , wherein the aqueous composition is a fluid for use in civil engineering for excavating and/or digging operations, a composition for household care, or a cosmetic composition.

19. The method of claim 1 , wherein the polymer is effective to promote the suspending of the dispersed solid or liquid particles in the aqueous medium at a temperature of greater than or equal to 100° C.

20. The method of claim 1 , wherein the polymer is prepared by inverse emulsion polymerization of at least one monomer Ab comprising sulphopropyldimethylammoniopropylmethacrylamide and one or more nonionic monomers Ba, wherein the amount of sulphopropyldimethylammoniopropylmethacrylamide is at least 10 mole % of the combined amount of monomers Ab and monomers Ba.

21. The method of claim 20 , wherein the polymer is effective to promote the suspending of the dispersed solid or liquid particles in the aqueous medium at a temperature of greater than or equal to 150° C.

22. The method of claim 1 , wherein the suspension comprises greater than or equal to 1% but less than or equal to 20% by weight of the polymer.