Materials for bio-sensors and renewable energy applications: Fabrication of mesoporous metal oxide films by the three-dimensional replication of block copolymers

Since their discovery in the early 1990's, mesoporous materials have been a field of vast growth and widely studied for various potential applications. The inherent well-defined pore structure is one attractive characteristic of these materials. Desirable functional materials may be infiltrated into these pores to generate a responsive device for specified applications. Likewise, the desired application of these materials dictates the domain size ( d-spacing) and morphology of these materials.; The use of two novel methods for mesoporous material fabrication will be introduced. First, the fabrication of mesoporous titania by the 3-D replication of block copolymers using supercritical carbon dioxide as a delivery medium will be implemented. Catalyst-doped block copolymer templates were spin-coated onto suitable substates and exposed to a solution of supercritical carbon dioxide and titania precursor. The precursor readily diffused into the swollen template and reacted with the catalyst, thus selectively condensing in a single domain. This method was extended for the fabrication of well ordered mesoporous titania thin films for sensor and renewable energy applications. The final well-ordered structures were analyzed with XRD, TEM, and GISAXS.; The second method introduced involves an aqueous method to fabricate mesoporous silica at neutral pH and ambient conditions through the incorporation of a bifunctional catalyst into an amphiphilic surfactant template. Highly condensed porous silica nanoparticles were formed at these conditions providing for excellent materials for sensor-type applications. These materials exhibited unusually high linking leading to low thermal shrinkage. NMR, TEM, and SAXS were utilized to characterize these particles.