PNNL

Abstract

Surface chemistry is one of the most important properties of mesoporous materis for many applications. There are several approaches to functionalize mesoporous materials in order to tailor the surface chemistry: one step synthesis by co-condensation, direct silanation of partially hydroxylated surface, controlled hydrolysis and condensation, and silanation using supercritical fluid as the reaction medium. Varying the amount chemically and physically adsorbed water can systematically tailor the quality and the population denstiy of functional groups. Furthermore, using supercritical fluid as the reaction medium, organic molecules can be effectively delivered and attached to the internal surfaces of pores less than 1 nm in diameter. The abiltiy to construct high quality functional monolayers allows rational design of molecular recongnition and binding sites in mesopoous materials, and has led to the development of very efficient adsorbing materials. One approach to form a host structure that matches the size and shape of the target species is to take advantage of the coordinate chemistry between the functional molecules and metal ions. Highly selective bindings of the target species have been observed against competing species of similar sizes and shapes. More sophisticated surface sites can be constructed for the recognition of complicated molecules and species using large pore mesoporous materials.