Porosity in hexylene-bridged polysilsesquioxanes: Effects of monomer concentration

摘要

Hexylene-bridged polysilsesquioxanes can be prepared as mesoporous or non-porous xerogels simply by switching from basic to acidic polymerization conditions. In this study, we looked at the effect of monomer concentration on porosity of hexylene-bridged xerogels prepared under acidic and basic conditions. 1, 6-Hexylene-bridged polysilsesquioxanes were prepared by sol-gel polymerizations of 1, 6-bis(triethoxysilyl)hexane 1 with concentrations between 0. 1 to 1.2 M in ethanol. Gelation times ranged from seconds for 1.2 M concentration to months for 0.2 M. The gels were processed into xerogels by an aqueous work-up and the dry gels characterized by scanning electron microscopy (SEM), solid state (sup 13)C and (sup 29)Si CP MAS NMR spectroscopy, and gas sorption porosimetry.