Porous reduced ceramic monoliths derived from silicon- and titanium-based preceramic polymer gels

Abstract

Preceramic polymer routes, which produce ceramic products called polymer-derived ceramics (PDCs) from molecular precursors, have been developed as a powerful tool to synthesize reduced ceramics in different morphologies (fibers, coatings and monoliths) for over half a century. In recent years, pore control of porous ceramic monoliths has attracted attention for improving their functionalities, which has driven the preceramic polymer routes to be integrated with other synthetic techniques for porous materials such as templating, foaming, emulsion and phase separation. This article briefly overviews porous PDC monoliths with a special emphasis on those derived from porous preceramic polymer gels which are prepared via the sol–gel process accompanied by spinodal decomposition. Ceramization behaviors of Si- and Ti-based preceramic polymers are highlighted in terms of crystal transition and variation of pore properties in different length scales.