US Patent 7700702 High molecular weight associative amphoteric polymers and uses thereof

High molecular weight associative amphoteric polymers for increasing the viscosity of aqueous solutions, comprise: at lease one cationic monomer derived from acrylamide bearing at least one hydrophobic chain of 8 to 30 carbon atoms; 1 to 99.9 mole % of at least one anionic monomer; and 1 to 99 mole % of one or several non-ionic water-soluble monomers. Aqueous solutions containing said polymers find uses in industry, in particular the oil, paper, water treatment, mining, cosmetics, textile, detergency industries and generally in all industrial techniques using thickened solutions.