Preparation and microstructural analysis of poly(ethylene oxide) comb-type grafted poly(N-isopropyl acrylamide) hydrogels crosslinked by poly(ϵ-caprolactone)

Poly( N -isopropyl acrylamide) (PNIPAAm)- graft -poly(ethylene oxide) (PEO) hydrogels crosslinked by poly(ϵ-caprolactone) diacrylate were prepared, and their microstructures were investigated. The swelling/deswelling kinetics and compression strength were measured. The relationship between the structure and properties of hydrogel are discussed. It was found that the PEO comb-type grafted structure reduced the thermosensitivity and increased the compression strength. The addition of poly(ϵ-caprolactone) (PCL) accelerated the deswelling rate of the hydrogels. Meanwhile, the entanglement of PCL chains restrained the further swelling of the network of gels. The PCL crosslinking agent and PEO comb-type grafted structure made the behavior of the hydrogels deviate from the rubber elasticity equations. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013