Abstract: The graft copolymers polyacrylamide-graft-poly(N-isopropylacrylamide) were synthesized by polymerization of acrylamide and macromonomers poly(N-isopropylacrylamide) with acrylamide end group in aqueous solution. The macromonomers with different molecular weights were prepared by 2 steps: (1) synthesis of amino-end functionalized poly(N-isopropylacrylamide) macromonomer by radical polymerization of NIPAm with 2-aminoethanethiol hydrochloride as chain transfer agent; (2) conversion of amino-end group to acrylamide-end group by reaction with acryloyl chloride. In aqueous solution this graft copolymer shows thermoassociating characters, and its associating temperature is determined by the cloud point of the side chain polymer, independently with the content and length of the PNIPAm side chain. The results show that these graft copolymers have thermothickening effect, i.e. the viscosity of PAM-g-PNIPAm aqueous solution increases with the increasing of temperature above its cloud point.

Key words: Macromonomer, Polyacrylamide-g-poly(N-isopropylacrylamide), Thermoassociating, Amphiphilic graft polymer