Preparation of low-density carbon aerogels by ambient pressure drying

With the addition of hexamethylenetetramine (HMTA) and alcohol as solvent, an ambient pressure drying technique was developed for the fabrication of low-density organic aerogels and related carbon aerogels. When a suitable ratio of resorcinol to HMTA (R/H ratio) and ratio of resorcinol to solvents (R/S ratio) are selected, the low-density alco-gels obtained can be dried under ambient pressure conditions without observable shrinkage. The addition of HMTA increases the size of carbon nano-particles and the pore size of the aerogels that are produced. The carbon aerogels prepared in this work have similar nano-particle structures typical of the aerogels prepared with CO2 or by the isopropanol supercritical drying technique. (C) 2004 Elsevier Ltd. All rights reserved.