Optically, defined multifunctional patterning of photosensitive thin-film silica mesophases

Photosensitive films incorporating molecular photoacid generators compartme ntalized within a silica-surfactant mesophase were prepared by an evaporati on-induced self-assembly process. Ultraviolet exposure promoted localized a cid-catalyzed siloxane condensation, which can be used for selective etchin g of unexposed regions; for "gray-scale" patterning of refractive index, po re size, surface area, and wetting behavior; and for optically defining a m esophase transformation (from hexagonal to tetragonal) within the film. The ability to optically define and continuously central both structure and fu nction on the macro- and mesoscales is of interest for sensor arrays, nanor eactors, photonic and fluidic devices, and low-dielectric-constant films.