Temperature- and pH-responsive behavior of a novel copolymer of (PP-g-DMAEMA)-g-AAc

Graft copolymers of 2-(dimethylamino)ethylmethacrylate (DMAEMA) and acrylic acid (AAc) onto polypropylene films were investigated for obtaining a pH- and thermo-sensitive material. DMAEMA and AAc were grafted by direct irradiation and pre-irradiation methods, respectively, using a Co-60 gamma-source. Due to the acidic and basic nature of the monomers, this novel copolymer corresponds to the class of polyzwitterions. Their behavior was studied in presence of different buffer solutions from pH 2 to 12 for different grafting percentages (from 9 to 362%) of AAc and keeping the DMAEMA grafting percentage constant. These modified films showed the same critical pH point at 7.6 in a range of temperatures from 23 to 37 A degrees C. The swelling percentage showed a dependence on AAc content and pH. The lower critical solution temperature was observed at 36 A degrees C when AAc content was less than 30% of grafting. The grafted films were characterized by swelling behavior, FTIR-ATR and UV-Vis spectrometry for study of loading and release of vancomycin as a model drug at room temperature.