Interpenetrating Thermo and pH Stimuli‐Responsive Polymer Networks of PAAc/PNIPAAm Grafted onto PP

A new strategy was used to prepare an interpenetrating polymer network of two stimuli‐responsive polymers, a thermosensitive poly N‐isopropylacrylamide (PNIPAAm) and a pH sensitive poly(acrylic acid) (PAAc) grafted onto poly(propylene) (PP) films (PP‐g‐PAAc). Three consecutive steps were used: graft copolymerization of PAAc onto PP films by gamma radiation, crosslinking of PP‐g‐PAAc to form the first network, and synthesis of a second network of PNIPAAm in situ within the crosslinked PP‐g‐PAAc by chemical polymerization and crosslinking. The phase transition temperature (LCST), measured by swelling measurements and DSC, the pH critical point, obtained by swelling, and the SEM derived morphology of network samples are reported. magnified image