Temperature and pH-sensitive swelling behavior of binary DMAEMA/4VP grafts on poly(propylene) films

Poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) is a polymer or hydrogel that is both thermosensitive and pH sensitive, with a low critical solution temperature (LCST) around 38 degrees C and a pH critical point of 2.5. Poly(4-vinylpyridine) (P4VP) shows pH sensitivity with a critical point of 5.1. Grafting of stimuli- sensitive polymers onto mechanically durable poly(propylene) (PP) substrates was used in this study. We have focused on the influence of temperature and pH on the response of binary graft films produced by gamma irradiation in one and two steps. An LCST- type hydration transition in the grafts was observed by measuring swelling of the films and water contact angle at different temperatures and pH. An upper critical solution temperature (UCST)-type behavior was also observed by swelling PP-g-DMAEMA and DMAMEA/4VP binary grafting onto PP films at pH 2.2.