Gas Permeation and Microstructure of Silica Membranes Prepared Using an Organic Template Approach by Sol-Gel Processing

This paper investigates microporous amorphous silica membranes prepared using an organic template sol-gel approach. We find that the introduction of organic methacryloxypropyl ligands results in a reduced average condensation rate and a lower extent of branching that promotes the collapse of the hybrid network upon drying leading to relatively dense hybrid organic-inorganic xerogels and films. Microporous silica xerogels and membranes, prepared by oxidative pyrolysis of the organic templates at 300 °C for 5 hours in oxygen, contained pores with constrictions of approximately 0.35 nm in diameter with a very narrow size distribution, as evidenced by single gas permeation measurements of a series of probe molecules.