(317p) Ordered Mesoporous Silica Membranes: Preparation and Nanopermporometry Characterization

Ordered mesoporous silica membranes were prepared using the evaporative induced self assembly process. Silica sol solutions were prepared by following Honma et al. (Adv. Mater., 2000). The molar ratio of TEOS/ cetyl-trimethyl-ammonium chloride (CTMA-Cl) was ranged from 0.061 to 0.152, which gave lamellar, hexagonal and cubic structures after sin-coating on slide glasses. Porous alumina substrates (Anodisc20, 100, 200) were spin-coated with silica sol solutions, followed by firing at 450 C to remove the templates. Nanopermporometry characterization, which is a relatively new technique to measure pore sizes from 0.5 to 3 nm (Tsuru et al., J. Membr. Sci., 1998, 2001; Sep. Purif. Sci., 2003), was carried out to estimate the pore size distribution of the coated silica membranes. In addition, no pressure dependency of nitrogen permeance was observed, suggesting the transport mechanism obeyed Knudsen flow mechanism. Both characterization techniques confirmed that mesoporous silica membranes were successfully prepared using porous alumina supports, Anodisc. SEM and TEM observation revealed that silica layer was formed inside cylindrical pores, not on Anodisc substrates. Molecular weigh cut-offs (MWCO) in ethanol aqueous solution was approximately 2,000, confirming the successful preparation of pinhole-free ordered mesoporous membranes.