Synthesis and Characterization of Novel Poly(N-isopropylacrylamide-co-N,N′-dimethylaminoethyl methacrylate sulfate) Hydrogels

Poly(N-isopropylacrylamide-co-N,/N'-dimethylaminoethyl methacrylate sulfate) [P(NIPAM-co-DMAEMASA)] was prepared from N-isopropylacrylamide (NIPAM) and N,N-dimethylaminoethyl methacrylate sulfate (DMAEMASA) monomers, and its properties were compared with those of poly(N-isopropylacrylamide-co-N,/N'-dimethylaminoethyl methacrylate) [P(NIPAM-co-DMAEMA)] The copolymers were characterized by swelling measurements in distilled water (10-40 degrees C) and buffer solutions (I = 0 1 M, pH = 2 2-10 0), FTIR, DSC, and SEM methods The ESV's of the NIPAM-DMAEMASA copolymers in distilled water were 5 times higher than those of P(NIPAM-co-DMAEMA), they decreased with an Increase in comonomer (DMAEMASA/DMAEMA) content for both copolymers While NIPAM-DMAEMASA copolymers did not display any phase transition with temperature, the LCST of the NIPAM-DMAEMA copolymer was determined as 20 degrees C Both copolymers displayed a phase transition at pH = 5 0, but the pH of the phase transition for NIPAM-DMAEMA gels shifted to 7 0 with increased DMAEMA content Glass transition temperatures of NIPAM copolymers did not change with the type and content of comonomer