A new example of periodic mesoporous SiCO glasses with cubic symmetry stable at 1000°C

Abstract

Periodic Mesoporous Organosilicas (PMOs) have been used as precursors to produce porous Silicon Oxycarbide glasses after pyrolysis at 1000°C in inert atmosphere. Up to now only PMOs with cubic ordering could be successfully converted into an ordered mesoporous SiCO glass. In our work we prepared, under strong acidic media and using an inorganic salt, a PMO with cubic Fm3m phase starting from 1,2-bis(triethoxysilyl)ethane as organosilane and Pluronic^® F127 as templating agent. The as-prepared PMO has been characterized by XRD (Synchrotron beamline), N₂ adsorption/desorption and multinuclear solid state NMR (²⁹Si, ¹³C). After pyrolysis under argon flow the Fm3m phase is retained and the sample still displays a high surface area of 260 m²/g. Further characterizations were performed by ²⁹Si MAS NMR and at 1000°C the product can be described as a true SiCO glass with mixed SiC_xO_4-x units (0≤x≤4).