Thermoresponsive gelation behavior of poly(N-isopropylacrylamide)-block-poly(N-vinylpyrrolidone)-block-poly(N-isopropylacrylamide) triblock copolymers

In this contribution, we reported the synthesis of poly(N-isopropylacrylamide)- block -poly(N-vinylpyrrolidone)- block -poly(N-isopropylacrylamide) (PNIPAM- b -PVP- b -PNIPAM) triblock copolymers through sequential reversible addition–fragmentation chain transfer/macromolecular design via the interchange of xanthate (RAFT/MADIX) process. The triblock copolymers have been characterized by means of 1 H   nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). This ABA triblock copolymer displayed a typical thermoresponsive gelation behavior. In this work, the thermoresponsive gelation behavior was investigated by means of rheological measurements, micro-differential scanning calorimetry (Micro-DSC) and small angle X-ray scattering (SAXS). The thermoresponsive gelation behavior could endow the triblock copolymers with the potential application as injectable hydrogels.