Rheology modifier polymer

A method for making a direct emulsion of a copolymer in water, wherein the method comprises the polymerization of at least, expressed as a percentage by weight of each of the monomers based upon the total weight of the monomers:

• a) 10 to 80% by weight of methacrylic acid and, optionally, of acrylic acid;
• b) 15 to 80% by weight of at least one non-ionic vinyl monomer;
• c) 0.05 to 9.5% by weight of 2-acrylamido-2-methylpropane sulfonic acid or a salt thereof;
• d) 0.5 to 30% by weight of at least one monomer containing at least one hydrophobic group;
• and
• e) 0.01 to 5% by weight of at least one crosslinking monomer;
• said polymerization being carried out in the presence of at least one surfactant.

A direct emulsion of a copolymer in water, wherein the copolymer is polymerized from a monomer mixture comprising at least, expressed as a percentage by weight of each of the monomers based upon the total weight of monomers:

• (a) 10 to 80% by weight of methacrylic acid and, optionally, of acrylic acid;
• (b) 15 to 80% by weight of at least one non-ionic vinyl monomer;
• (c) 0.05 to 9.5% by weight of 2-acrylamido-2-methylpropane sulfonic acid or a salt thereof;
• (d) 0.5 to 30% by weight of at least one monomer containing at least one hydrophobic group;
• and
• (e) 0.01 to 5% by weight of at least one crosslinking monomer;
• wherein said emulsion contains at least one surfactant.