Poly(N-isopropylacrylamide)-block-poly(acrylic acid) hydrogels: synthesis and rapid thermoresponsive properties

In this contribution, we reported the synthesis of poly(N-isopropylacrylamide)-block-poly(acrylic acid) (PNIPAAm-b-PAA) copolymer networks via sequential reversible addition-fragmentation chain transfer (RAFT) polymerization. The PNIPAAm-b-PAA block copolymer networks were characterized by means of Fourier transform infrared spectroscopy (FTIR) and small angle X-ray scattering (SAXS). The volume phase transition (VPT) temperatures of the PNIPAAm-b-PAA hydrogels were measured by means of micro-differential scanning calorimetry (micro-DSC). It was found that the block copolymer hydrogels displayed the VPT temperatures lower than the control PNIPAAm hydrogel. Compared to the control PNIPAAm hydrogel, the deswelling and reswelling properties of the block copolymer hydrogels were significantly improved. The improved thermoresponsive properties of the PNIPAAm-b-PAA hydrogels have been interpreted on the basis of the formation of the architecture of the block copolymer networks.