POLY(PARA-PHENYLENE VINYLENE) SILICA COMPOSITE - A NOVEL SOL-GEL PROCESSED NONLINEAR OPTICAL MATERIAL FOR OPTICAL WAVE-GUIDES

We report here the first case (to our knowledge) of a compatible blend of an inorganic polymer, silica glass, and a pi-conjugated non-linear optical polymer, poly(p-phenylene vinylene), homogeneously miscible over wide composition ranges. This composite material was prepared by combining sol-gel processing techniques applicable to the silica glass with those used for the synthesis of the organic polymer from a water/alcohol-soluble sulphonium salt precursor. In this preparation the organic polymer precursor and the inorganic sol were mixed in a common solvent and converted to the final composite material. The thermal conversion of the precursor polymer released HCl, which catalysed the gelation of the inorganic sol. The resulting composite material has been characterized by infra-red and ultra-violet/visible spectral analysis and thermogravimetric and differential scanning calorimetric analysis. The material can be cast into various forms. Thin films cast by the doctor-blading technique exhibit good optical quality and show promise for application as optical waveguides.