Synthesis and behavior in aqueous solution of carboxymethyl pullulan-graft-poly(N-isopropylacrylamide-co-methacrylamide)

Abstract

Stimuli-responsive polymers are fascinating materials because they mimic the behavior of living systems. This ability to respond to the action of certain stimuli makes them interesting both from the point of view of the theoretical study of their behavior in solution and of biomedical applications. In this regard, semitelechelic oligomers of N-isopropylacrylamide-co-methacrylamide (thermosensitive) with amine end groups were grafted onto previously synthesized carboxymethyl pullulan (sensitive to pH). The oligomers as well as the graft copolymer were characterized in terms of composition, molecular mass, number of grafts on the pullulan macromolecule, grafting density, and Kuhn segment length. Thermoresponsiveness of the grafted copolymer was studied in wide concentration and pH ranges. The onset temperature of phase separation proved to be independent of concentration and influenced by pH in highly basic solutions.The time of the copolymer response to abrupt change in temperature was analyzed.