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. Q 2002 Wiley Periodicals, Inc.