Epoxy/SiO2 Interpenetrating Polymer Networks

Abstract

We demonstrate a potentially useful method of generating an SiO2 morphology, in situ, with interpenetrating polymer networks (IPN) chemistry. Organic/inorganic IPNs were synthesized with an organic phase made of epoxy resin and an SiO2 phase made by sol—gel chemistry. The two types of polymerization used were sequential and simultaneous with SiO2 content ranging from 0.02 to 0.43 g SiO2/g total weight. The resultant morphologies were examined by small angle X-ray scattering and transmission electron microscopy. The sequential IPNs were strongly phase separated into a finely divided SiO2 phase of ∼10 nm size scale. The simultaneous IPNs were weakly phase separated with considerable mixing in the phases. Thermal studies showed increased thermal stability for the IPNs, compared with unfilled epoxies or physically mixed silica filled epoxies.