Graft copolymers composed of high molecular weight poly(ethylene oxide) backbone and poly(N-isopropylacrlylamide) side chains and their thermoassociating properties

Novel, water‐soluble thermoassociative graft copolymers based on high molecular weight (HMW) poly(ethylene oxide‐co‐glycidol) backbone and relatively short grafts of poly‐N‐isopropyl acrylamide (NIPAAm) were prepared. The copolymer precursors with two architectures (block and graft) were synthesized using Ca‐amide‐alkoxide initiators. The OH groups in the copolymer precursors have been utilized for grafting NIPAAm using ceric ion (Ce4+) redox initiation. The idea was to imprint the “smart” properties of PNIPAAm grafts into common HMW poly(ethylene oxide). The sensitive moieties undergo reversible association transitions by changing the temperature of dilute and semidilute aqueous solutions of the copolymers. Associative properties were studied by viscosity and rheology measurements. Two types of interactions, induced by heating, depending on the copolymer concentration namely intra‐ and intermolecular association were observed.