Surfactant assisted syntheses of monolithic hybrid ceramics with hierarchical porosity

Abstract

A surfactant assisted emulsion-based syntheses route is presented for obtaining organo-silica-based monolithic hybrid ceramics with a hierarchical pore size distribution and tailorable surface characteristics. Methyl polysiloxane (MK) and methyl-phenyl polysiloxane (H44) with varying mixing ratios are selected as precursors, cross-linked and subsequently pyrolyzed at 500 °C or 600 °C, respectively. By adjusting the oil/water ratio and by tailoring the surfactant concentration controlled micro and macropore distributions with mesoscopic cell windows are obtained. After pyrolysis, specific surface areas of up to 600 m2/g are achieved. In addition, due to the distinguished pyrolysis decomposition behavior of MK and H44, the adjustment of the surface characteristics in terms of hydrophobicity or hydrophilicity is demonstrated. The presented surfactant assisted emulsion-based process is hence highly suitable for tailoring pore size distribution and surface characteristics at the same time. Both material properties are pivotal features for catalysis and gas separation applications.