Nanoporous silica based on sol-gel processing and templating approaches

Nanoporous (microporous and mesoporous) silicas have extensive industry applications. This study attempts to develop a new methodology to synthesize nanoporous silica thin films, membranes, and particles for separation, catalysis, and sensor applications, using sol-gel process techniques and templating approaches. The templating approaches are based on the formation of dense organic/inorganic hybrid materials incorporating pore templates (covalently bonded organic ligands or selfassembled surfactant micelles and liquid crystals) and the subsequent removal of the templates to create a random microporous network or an ordered mesoporous network.; Organic templating ligands, including ethyl (.CH ₂CH₂.), methacryloxypropyl (H₂C=C(CH ₃)CO₂(CH₂)₃.), and diethylphosphatoethyl ((C ₂H₅O)₂POCH₂CH₂.) ligands, have been successfully used to synthesize microporous silica membranes with molecular sieving effects. However, such microporous silica materials with small pore size and high porosity are not thermally stable, and metal ions like La3+ have been used to enhance their thermal stability.; A new methodology involving evaporation-induced surfactant self-assembly has been successfully developed to synthesize silica thin films, membranes, particles, and nano-composite materials with highly ordered mesophase structures through dip coating or aerosol processes. This method has been extended to synthesize hybrid mesophase thin films and particles with controlled pore structure and pore surface chemistry by combining hybrid sol-gel chemistry techniques and the surfactant templating approach. FTIR-ATR waveguide-based chemical sensors with organic-functional porous coatings have been developed to detect low concentration of organic compounds in water.; The studies described in the dissertation have created several new directions toward new materials for separations, adsorbents, catalysis, sensors, custom designed fillers, and other advanced applications.