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

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