Poly(ethylene oxide)-grafted poly(N-isopropylacrylamide) networks: Preparation, characterization and rapid deswelling and reswelling behavior of hydrogels

Poly(ethylene oxide)-grafted poly(N-isopropylacrylamide) networks (PNIPAAm-g-PEO) were prepared via the reversible addition-fragmentation chain transfer polymerization (RAFT) of N-isopropylacrylamide with trithiocarbonate-terminated poly(ethylene oxide) and N,N′-methylenebisacrylamide as the chain transfer agent and the crosslinking agent, respectively. It was found that the PNIPAAm-g-PEO copolymer networks were microphase-separated and that PEO microdomains were dispersed in the PNIPAAm matrix. The hydrogel behavior of the PNIPAAm-g-PEO networks was investigated using swelling, deswelling and reswelling tests. The PNIPAAm-g-PEO hydrogels displayed faster responses to external temperature changes than did the control PNIPAAm hydrogel.