The copolymerization of acrylamide(AM)

sodium 2-acrylamido-2-methyl-propane-sulfonate(NaAMPS) and styrene(St) was carried in microemulsion madium

and tercopolymer AM／NaAMPS／St containing strong anionic group —SO3Na and hydrophobic association group St was synthesized. The structure and composition of the copolymer were characterized by FTIR spectrum

UV spectrum and element analysis．The solution viscosity of the copolymers was determined using an Ubbelohde viscometer

and the intrinsic、riscosities by which molecular weight can be indicated relatively were determined with the method of dilute extensional method．The apparent viscosities of aqueous solutions and brine of the copolymers were measured using a low shear rotational viscometer．The hydrophobically associating property and influence of ionic groups on the hydrophobic association property were investigated. The experimental results are as follows．After incorporating strong anions and hydrophobic groups at the same time in the backbone of polyacrylamide

the viscosity of the copolymer aqueous solution will increase obviously under coordination of electric viscosity of ions and hydrophobic association property of hydrophobic group and the salt resistance of the copolymer will increase evidently under the combining of strengthening hydrophobic association by salt and greater tolerating salt of strong anions. The hydrophobic association property of hydrophobic association group St is weakened and the critical associating concentration of the copolymer is increased due to existing of strong anionic groups in macromolecular chains.