Thermoreversible hydrogels. VII. Synthesis and swelling behavior of poly(N-isopropylacrylamide-co-3-methyl-1-vinylimidazolium iodide) hydrogels

A series of N-isopropylacrylamide/3-methyl-1-vinylimidazolium iodide (NIPAA m/MVI) copolymer gels were prepared from the various molar ratios of NIPAAm , cationic monomer MVI, and N,N'-methylene bisacrylamide (NMBA) in this stu dy. The influence of the amount of MVI in the copolymer gels on the swellin g behaviors was investigated in various aqueous saline solutions. Results s howed that the swelling ratios (SRs) of copolymer gels were significantly g reater than those of NIPAAm homapolymer gels, and the higher the MVI conten t, the higher the volume phase transition temperature. The SRs far the NIPA Am/MVI copolymer gels decreased with an increase of the salt concentration. In various saline solutions, results showed that the effect of divalent io ns on the SR was greater than that of monovalent ions for these hydrogels. (C) 1999 John Wiley & Sons, Inc.