Phase separation in silica sol-gel system containing poly(ethylene oxide) .2. Effects of molecular weight and temperature

Phase separation and gelation behaviors have been studied for acid-catalyzed, alkoxide-based silica systems containing poly(ethylene oxide), PEO. In order to clarify the role of PEO in a phase-separating sol-gel system, the effects of the molecular weight of PEO and the reaction temperature were investigated in detail. The PEO concentration of the highest phase-separation tendency slightly increased along with a decrease in the molecular weight, suggesting that the phase-separation behavior is mainly governed by an interaction between PEO and the solvent mixture. The reaction temperature affected the morphology-composition relationship mainly by its effect on the sol-gel transition kinetics.