PHASE-SEPARATION IN SILICA SOL-GEL SYSTEM CONTAINING POLY(ETHYLENE OXIDE) .1. PHASE RELATION AND GEL MORPHOLOGY

Phase separation and gelation behaviors have been studied for the acid -catalyzed. alkoxide-based silica systems containing poly(ethylene oxi de) (PEO) with an average molecular weight of 100000. Gels with microm eter range interconnected porous morphology were obtained similarly to the systems containing other water-soluble polymers, in which the str ucture development by the spinodal decomposition and the gel forming p rocess take place concurrently. In spite of the morphological similari ty, the thermogravimetric analysis revealed that the reacting solution decomposed into phases one rich in PEO and the other rich in solvent. Macropore volume of gels depended mainly on the amount of solvent pha se.