Bicontinuous Silica-Epoxy Nanocomposites by Aerogel Infusion

Interpenetrated, bicontinuous nanocomposites are formed by fully infusing monolithic mesoporous silica (silica aerogel) with epoxy resin. The long-range connectivity of the silica network facilitates direct load transfer and enforces sample homogeneity. The silica networks are prepared using sol-gel chemistry, informed by new phase diagrams, adapted to maximise reinforcement content in the subsequent bicontinuous composite. The infusibility of the aerogels is correlated to pore characteristics determined by gas sorption, as a function of silica aerogel density. Silica reinforcement loadings of up to 22 silica vol.% are fully consolidated, with only a modest reduction in glass transition temperature and no change in cure conditions. The reinforcement improves both hardness (+23 %) and reduced modulus (+17 %) of the baseline resin. These properties increase with aerogel content via a power law relationship which demonstrates the direct role of the connected silica phase as a reinforcing network and motivates future studies to extend the applicable range.