THERMOREVERSIBLE HYDROGEL - V - SYNTHESIS AND SWELLING BEHAVIOR OF THE N-ISOPROPYLACRYLAMIDE CO TRIMETHYL METHACRYLOYLOXYETHYL AMMONIUM IODIDE COPOLYMERIC HYDROGELS

A series of N-isopropylacrylamide/trimethyl methacryloyloxyethyl ammon ium iodide (NIPAAm/TMMAI) copolymeric gels are prepared from the vario us molar ratios of NIPAAm, cationic monomer TMMAI, and N,N'-methylene bisacrylamide (NMBA) in this article. The influences of the amount of the cationic monomer in the copolymeric gels on the swelling behavior in water, various saline solutions, and various temperatures are inves tigated. Results show that the swelling ratios of copolymeric gels are significantly larger than those of pure homopolymer NIPAAm gel, and t he more the TMMAI content, the higher the gel transition temperature. In the saline solution, results show that the swelling ratio of pure N IPAAm gel has not significantly changed with an increase of the salt c oncentration until the salt concentration is larger than 0.1M. The swe lling ratios for the copolymeric gels NIPAAm/TMMAI decrease with incre asing salt concentration. In various saline solutions, results show th at the anionic effects are greater than cationic effects in the presen ce of common anion, different cations and common cation, and different anions for these hydrogels. Finally, we also tested the reversibility of the NIPAAm/TMMAI copolymeric gels. The deswelling and reswelling k inetics are dependent on the temperature, which is below or above the gel transition temperature. The gel with little TMMAI content has a go od reversibility. (C) 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69 : 1793-1803, 1998.