Effect of initial sol concentration on the microstructure and morphology of carbon aerogels

Abstract

New carbon aerogels were prepared using Novolac sol as precursor. The elaboration process and the structural characterizations of these porous carbon materials are described in the present study. Series of monolithic carbon aerogels were prepared in 2-propanol by crosslinking Novolac with hexamethylene tetra amine catalyst via sol–gel polymerization in the solvent vapor-saturated atmosphere followed by pyrolysis. Low density materials (from 0.3 to 0.6 g/cm3) were obtained after pyrolysis. These newly carbon aerogels were characterized using mercury porosimetry, nitrogen adsorption and scanning electron microscopy. All prepared materials have shown a nanostructured solid network (specific surface areas between 554 and 635 m2/g) and all samples have pore volumes as large as 0.97 cm3/g. Influence of Novolac concentration in the initial sol on the carbon aerogel structure was investigated. A special attention was dedicated to the different microstructures and morphologies occurring after the elaboration process. In particular, changing solid network from colloidal to polymeric network was studied in terms of micro, meso and macro porosity. In parallel, mechanical properties were presented in terms of bulk modulus.