Influence of acid-base catalysis on the textural and thermal properties of carbon aerogel monoliths

Abstract

The preparation of carbon aerogel monoliths (CAMs) with low density, low thermal conductivity and high strength concurrently is a challenge, which restricts their application in the field of ultra-high thermal insulation. Acid and basic two-step catalysis was successfully used for preparing the low density CAMs with both high strength and low thermal conductivity. The linear phenolic oligomers originated from acid catalysis were fastened tightly to become robust skeleton architecture through later crosslinking polymerization resulted from base catalysis. The strong nanoporous structure can afford the capillary force during ambient drying and shrink little to obtain low density CAMs with high specific surface area, and endows the CAMs with high compressive strength. With no need to prepare composites, the failure strength and elastic modulus of pure CAMs can reach 1.76 MPa and 29.73 MPa, respectively, with the specific surface area of 689 m2/g and pore volume of 2.122 cm3/g. Moreover, the thermal insulation property of this CAM is very outstanding with the thermal conductivity at 2000 °C under 0.1 MPa argon atmosphere 0.809 W/(m•K), which is lower than commercially available carbon aerogel filled foam and carbon foam.