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Three series of thermosensitive copolymeric hydrogels were prepared from [3-(methacryloyloxy)propyl]trimethoxysilane (MPTMOS), [2-(methacryloyloxy)ethoxy]-trimethylsilane (METMS), and (methacryloyloxy)trimethylsilane (MTMS), referred to as the silane monomer, and N-isopropylacrylamide (NIPAAm) by solution polymerization. The influence of the structures and amounts of silane monomers on the swelling and drug-released behaviors were studied. The results showed that, because of the hydrophobicity of the silyl group, the more silane monomers in the copolymeric hydrogels the lower was the swelling ratio of the gels. The hydrophobicity of the silyl group affected the swelling mechanism, which resulted from the non-Fickian diffusion for the gels. The copolymeric gels clearly exhibited gel transition temperatures. The copolymeric hydrogels could be applied to a drug-release and drug-delivery system. The delivery amount would approach a steady state after three cycle operations of delivery. The gels also showed an on-off switch behavior on drug release depending on the temperature, and the gels released more CV with the gels in a swollen state.

The swelling behavior for a series of NIPAAm/NaAMPS copolymeric hydrogels with polyelectrolytic and thermosensitive properties was investigated in various saline solutions. The swelling ratios for the present copolymeric hydrogels were affected by the saline solution, which is the result of the neutralization of the cations in the external solution with the negative charges on the polymeric side chains. The adsorption of aniline by the gels increased when the temperature was higher than the gel transition temperature, and this result showed that, when the gels were in hydrophobic state, the hydrophobic organic molecules were more easily adsorbed onto the gels. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1675–1684, 2001

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