Preparation and characterization of epoxy–silica networks chemically bonded through aminophenyl-trimethoxysilane

Epoxy–silica hybrids with interfacial bonding using aminophenyl-trimethoxysilane (APTMOS) have been prepared by the sol–gel process. In a sequential polymerization procedure the amine groups present on the APTMOS were used to partially cure diglycidyl ether of bisphenol-A (DGEBA) whereas the methoxy groups created silica-network simultaneously, through the sol–gel process. Complete curing and cross-linking were carried out later using curing agent jeffamine D-400 at higher temperature. The nature of silica network structure chemically bonded with the epoxy chains was studied by Fourier transformed infrared spectroscopy and the morphology of the hybrid through scattering electron and atomic force microscopies. The visco-elastic properties of the resulting hybrids were measured through dynamical thermal mechanical analysis. The effect of inter-phase bonding of the resulting hybrids and their thermal mechanical properties are compared with the similar DGEBA epoxy matrix where un-bonded silica network was produced from tetraethoxysilane. The properties of the hybrids using APTMOS show considerable improvement in thermal mechanical properties and the coefficient of thermal expansion is reduced in contrast to the un-compatiblized system.