Hydrophobic association and temperature and pH sensitivity of hydrophobically modified poly(N-isopropylacrylamide/acrylic acid) gels

摘要

Hydrophobically modified poly(acrylic acid/N-isopropylacrylamide) gels were synthesized by the radical copolymerization of acrylic acid /N-isopropylacrylamide with a small amount of the hydrophobic comonomer 2-(N-ethylperfluorooctanesulfoamido)ethyl acrylate, stearyl acrylate, or lauryl acrylate in tert-butanol with ethylene glycol climethacrylate as a crosslinker. Swelling kinetics and fluorescence measurements showed that the hydrophobic association ability of fluorocarbon groups was stronger than that of hydrocarbon analogues in modified hydrogels that contained both physical and chemical crosslinking networks. The effects of the fractions and the species of the hydrophobe on the gel swelling and pH and temperature sensitivity were studied. The results indicated that the swelling behavior and pH and temperature sensitivity of the gels were affected by the degree of hydrophobic modification. A hydrogel with a suitable 2-(N-ethylperfluorooctanesulfoamido)ethyl acrylate content (0.349 mol %) showed good pH and temperature sensitivity. (C) 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2406 -2413, 2003. [References: 25]