Microemulsion processing of silica-polymer nanocomposites.

Silica-polymer nanocomposites have been synthesized via polymerizable bicontinuous microemulsions to disperse functionalized/nonfunctionalized SiO2 nanoparticles uniformly in a polymerized microemulsion system as revealed by transmission electron microscopy. The effect of both types of SiO2 nanoparticles in the polymerized microemulsion increased its glass transition temperature (Tg) from 90 to 128 degrees C. TgS of functionalized silica nanocomposites were about 15 degrees C higher than those of nonfunctionalized samples. As expected, both hardness and modulus of the nanocomposites increased with the loading of both types of silica from 2 to 6 wt%. In the case of nonfunctionalized silica, the improvement of properties may be simply exerted by the conventional filler effect due to the better dispersion of nanoparticles of silica in fluid microemulsion prior to the polymerization. The additional effect for the functionalized silica containing a terminal vinyl group is that It could be grafted to the polymer matrix through cross-polymerization with microemulsion-formed polymer to establish strong nanocomposite networks.