Polymer-derived SiOC aerogel with hierarchical porosity through HF etching

Silicon oxycarbide (SiOC) aerogels have been synthesized from preceramic polymers via pyrolysis in inert atmosphere at 1200 and 1300 degrees C. The as synthesized materials have a typical colloidal microstructure with mesoporosity in the range 10-50 nm and no microporosity. HF acid attack of the SiOC aerogels dissolves preferentially the SiO2-rich phase and creates micro-and (small)mesopores (<10 nm) in the aerogels microstructure finally leading to a materials with hierarchical porosity. The HF post-pyrolysis treatment is more efficient for the SiOC aerogels pyrolyzed at the maximum temperature, i.e. 1300 degrees C, leading to a maximum value of specific surface area of 530 m(2)/g and total porosity of 0.649 cc/g. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.