The graft copolymers hydrolyzed polyacrylamide-g-poly(N-isopropylacrylamide-co-N

N-dimethylacrylamide) ［HPAM-g-P(NIPA-co-DMAM)

HGPID］ with different compositions and molecular masses of the side chains were prepared by the macromonomer copolymerization method.These graft copolymers had amphiphilic properties and showed thermo-associating characteristics as the temperature of their aqueous solution was higher than the association temperature.The association temperature was dependent on the cloud point of the side chain polymer

which was determined by the side chain composition.By changing the mole ratio of NIPA and DMAM in the side chain

the graft copolymers with the association temperature in the range of 37—63℃ were obtained.Above a certain concentration of the graft copolymers

their salt aqueous solutions exhibited thermo-thickening behavior.The effects of the composition and length of the side chain

the concentrations of the polymer and the added salt on the thermo-associting and thermo-thickening behavior were studied.