Ethylene–propylene copolymer/ordered polysilsesquioxane nanocomposites prepared via organic acid‐ or base‐catalyzed binary silica water‐crosslinking reactions

Abstract

AbstractIn situ silica sol–gel‐derived organic–inorganic hybrid materials, which comprise a vinyltrimethoxysilane‐grafted ethylene–propylene copolymer (EPR‐g‐VTMS) and n‐hexyltrimethoxysilane (HTMS), were successfully prepared in the presence of an organic acid and base catalyst. Benzenesulfonic acid and aniline were selected as the organic acid and base catalyst, respectively, to examine the progress and effect of progressive changes in the silane water‐crosslinking reaction of EPR‐g‐VTMS/HTMS composites. The water‐crosslinked EPR‐g‐VTMS/HTMS composites were characterized by means of attenuated total reflectance Fourier transform infrared spectroscopy, gel content, solid‐state 29Si cross‐polarization/magic‐angle spinning NMR, wide‐angle X‐ray scattering, tensile strength and field‐emission scanning electron microscopy measurements. These results revealed that the type of catalyst has a substantial influence on the nature of siloxane bonds and eventually the physical tensile properties of the water‐crosslinked EPR‐g‐VTMS/HTMS composites, which can be explained mainly from knowledge of the traditional acid‐ and base‐catalyzed silica sol–gel reaction. Moreover, an in‐depth analysis of the aniline‐catalyzed composites indicated the formation of ladder‐type poly(n‐hexylsilsesquioxane)s and the presence of a highly ordered structure with a thickness equal to the length of two n‐hexyl groups in all‐trans conformation. We demonstrate potential for the future design of highly ordered silicate‐based organic–inorganic hybrid nanocomposites. Copyright © 2009 Society of Chemical Industry