SYNTHESIS OF PERIODIC MESOPOROUS SILICA THIN-FILMS

We describe a synthetic method for the formation of surfactant-templat ed periodic mesoporous silica thin films. The films, when deposited be tween 0.22 < t/t(gel) < 0.67, are crack-free, consist of aggregated su bmicrometer particles, each of which contains the familiar honeycomb a rrangement of 30-44 Angstrom diameter channels, and have specific surf ace areas greater than 400 m(2)/g. The synthetic method, which we call gas-catalyzed thin film synthesis (GCTFS), involves diffusing ammonia into a homogeneous micellar coating solution on a nonporous substrate . This method ameliorates the problems associated with coating substra tes from inhomogeneous solutions. We have studied and optimized GCTFS with light scattering, Si-29 NMR, XRD, optical microscopy, SEM, TEM, a nd isothermal N-2 sorption measurements.