POLY(2-HYDROXYETHYL METHACRYLATE-CO-SULFOBETAINE) HYDROGELS - II - SYNTHESIS AND SWELLING BEHAVIORS OF THE [2-HYDROXYETHYL RYLATE-CO-3-DIMETHYL(METHACRYLOYLOXYETHYL)AMMONIUM PROPANE SULFONATE] HYDROGELS

A series of the 2-hydroxyethyl methacrylate/3-dimethyl- (methacryloylo xy-ethyl) ammonium propane sulfonate (HEMA/DMAPS) copolymeric gels was prepared from various molar ratios of HEMA. and the zwitterionic mono mer DMAPS, The influence of the amount of the zwitterionic monomer in the copolymeric gels on the swelling behaviors in water, various salin e solutions, and temperature was investigated. The results indicate th at the PHEMA hydrogel (DO) and lower DMAPS content of the HEMA/DMAPS c opolymeric gel (D1) exhibit overshooting phenomena in the dynamic swel ling behavior. The maximum overshooting value decreases with increase in temperature. In the equilibrium swelling ratio, the PHEMA hydrogel exhibits a minimum swelling ratio at 55 degrees C. Then, the minimum s welling ratio diminishes gradually with increasing of the DMAPS conten t in the HEMA/DMAPS copolymeric gels. In the saline solution, the swel ling ratios of HEMA/DMAPS copolymeric gels increase rapidly with incre asing of concentration of the salt with. a smaller ratio of the charge /radius. (C) 1998 John Wiley & Sons, Inc.