2. Methods
The model developed in Part I is applied to nitrogen adsorption isotherms obtained for a series of silica aerogels whose densities Silica aerogel was prepared from tetramethoxysilane at are varied by partial sintering. The isotherms are adequately deneutral pH, as described in Ref. 7; pieces from three nomiscribed by a cubic network model, with all of the pores falling in nally identical samples were used for all the measurements the mesopore range; the adsorption and desorption branches are reported here. Supercritical extraction of ethanol was carried fit by the same pore size distribution. For the least dense gels, a out at 300ЊC and 13 MPa. The aerogel was then oxidized substantial portion of the pore volume is not detected by condensato remove the esterification (i.e., a monolayer of methoxy tion. The model attributes this effect to the shape of the adsorbate/ groups on the surface of the aerogel) by heating in air at 4ЊC/ adsorptive interface, which can adopt zero curvature even in mesomin to 150ЊC and 400ЊC, with 5 h holds at each temperature.
pores, because of the shape of the network.