MORPHOLOGICAL INVESTIGATION OF HYBRID MATERIALS COMPOSED OF PHENOLIC RESIN AND SILICA PREPARED BY IN-SITU POLYMERIZATION

Morphological investigations for hybrid materials composed of phenolic resin and silica, prepared by in situ polymerization of silicon alkox ide, were performed using TEM. Irregularly shaped silica particles a f ew tens of nanometres in size, composed of hyper-fine particles, are h omogeneously dispersed in the transparent hybrid materials forming a p artial or uniform silica network depending on the silica content. In t he translucent hybrid materials, the dispersion of complex silica aggr egates (ca. 100 nm) were observed uniformly throughout the sample. In the opaque hybrid materials, silica particles of micrometre range were found to be incorporated uniformly, although the interface was uneven . Such large silica particles embedded in the hybrid material contain both silicon oxide and phenolic resin in an interpenetrating network o f both components. It was considered that these different morphologies observed in transparent similar to opaque hybrid materials are caused by freezing-in the silica aggregation at different stages in the cour se of phase-separation between phenolic resin and silica formed in sit u. These morphological characteristics were also compared with those o f conventional phenolic resin/silica glass composites. (C) 1998 Elsevi er Science Ltd. All rights reserved.