间苯二酚－甲醛炭气凝胶的常压干燥法制备及其表征

With the addition of hexamethylenetetramine (HMTA), an ambient pressure drying technique was developed for the fabrication of resorcinol-formaldehyde-based carbon aerogels. The preparation conditions such as reagent content and HMTA content were explored, and the nano-structures of carbon aerogels and their precursory organic aerogels obtained were characterized by means of SEM, nitrogen adsorption and Mercury porosimetry. The representative carbon aerogels obtained here have a binary pore size distribution with 0.43nm micropore and 200nm macropore. Their interconnected particles size and BET surface area is about 100nm and 750 m2/g, respectively; and their pore volume measured by Mercury porosimetry is about 2.27 cm3/g. Both HMTA content and reagent content can affect the pore structure of the aerogels. Additionally, it is required that the reagent content should be high enough to form organic gel. For organic aerogel and carbon aerogels, the adsorption for the polar solvent vapours is higher than that for the unpolar solvent vapours. For various solvent vapours, the adsorption of carbon aerogels is higher than that of organic aerogels. The success of the ambient pressure drying technique in this study should be ascribed to the decrease in the capillary pressure and the increase in the strength of the network.