Phase Separation in Silica Sol–Gel System Containing Poly(ethylene oxide). I. Phase Relation and Gel Morphology

Phase separation and gelation behaviors have been studied for the acid-catalyzed, alkoxide-based silica systems containing poly(ethylene oxide) (PEO) with an average molecular weight of 100000. Gels with micrometer range interconnected porous morphology were obtained similarly to the systems containing other water-soluble polymers, in which the structure development by the spinodal decomposition and the gel forming process take place concurrently. In spite of the morphological similarity, 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 phase.