Phase Separation in Sol–Gel Process of Alkoxide‐Derived Silica‐Zirconia in the Presence of Polyethylene Oxide

Abstract

Phase separation in a sol–gel process of SiO2–ZrO2 in the presence of polyethylene oxide is investigated. An amorphous gel with interconnected macroporous morphology is obtained when phase separation and sol–gel transition concur to fix a transitional structure of spinodal decomposition. Macropore size, together with connectivity of the pores and gel skeleton, can be controlled precisely by selecting an appropriate starting composition for preparation at a zirconium content ≤11.7 mol%. The macroporous gel retains additional mesopores <4 nm and exhibits typical bimodal pore size distribution. The addition of ZrO2 in SiO2 improves the thermal stability of both macroporous and mesoporous structures.