Effect of silane coupling agent on swelling behaviors and mechanical properties of thermosensitive hybrid gels

A series of organic–inorganic hybrid thermosensitive gels with three different structures were prepared from N-isopropylacrylamide (NIPAAm), and N, N′-methylenebisacrylamide (NMBA) and tetraethoxysilane (TEOS) [N-IPN]; NIPAAm, 3-(trimethoxysilyl) propyl methacrylate (TMSPMA) as coupling agent and TEOS [NT-IPN]; and NIPAAm, TMSPMA, and TEOS [NT-semi-IPN] by emulsion polymerization and sol–gel reaction in this study. The effect of different gel structures and coupling agent on the swelling behavior, mechanical properties, and morphologies of the present gels was investigated. Results showed that the properties of the gels would be affected by the gel networks such as IPN or semi-IPN and with or without existence of TMSPMA as the bridge chain between networks. The NT-semi-IPN gel had higher swelling ratio and faster diffusion rate because poly(NIPAAm) moiety in the semi-IPN gels was not restricted by NMBA network. However, the IPN gels such as N-IPN and NT-IPN had good mechanical properties and lower swelling ratio, but had a poor thermosensitivity due to the addition of coupling agent, TMSPMA, into the gel system that resulted in denser link between organic and inorganic components. The morphology showed that IPN gels had partial aggregation (siloxane domain) and showed some denser phases. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009