Km. Huh et al., Synthesis and characterization of dextran grafted with poly(N-isopropylacrylamide-co-N,N-dimethyl-acrylamide), MACRO CH P, 201(5), 2000, pp. 613-619
Graft copolymers consisting of dextran as a main chain and poly(N-isopropyl
acrylamide-co-N,N-dimethylacrylamide) (poly(NIPAAm-co-DMAAm)) as graft chai
ns were synthesized. For the synthesis of the graft copolymers, a semitelec
helic poly(NIPAAm-co-DMAAm) with an amino end-group was obtained by radical
copolymerization with ethanethiol as a chain transfer agent, followed by a
coupling reaction of its hydroxyl end-group with ethylenediamine. Graft co
polymers with various length of the grafts were obtained from coupling reac
tions between carboxymethyl dextran and poly(NIPAAm-Co-DMAAM) in the presen
ce of a water-soluble carbodiimide. The graft copolymers in phosphate buffe
r exhibit lower critical solution temperatures due to thermosensitivity of
their grafts. There is no significant change in the hydration-dehydration b
ehavior of the poly(NIPAAm-co-DMAAm) chain after the grafting reaction. The
existence of such grafts in dextran may play an important role for modulat
ed degradation in synchronization with temperature.