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Silica aerogels were prepared at ambient drying by using ethanol/trimethylchlorosilane (TMCS)/heptane solution as pore water exchange and surface modification of the wet gel before drying. The obtained silica aerogels exhibit a sponge-like structure with uniform pore size distribution. The effects of heat-treatment on the hydrophobicity, specific surface area and other properties were investigated. The results indicated that the hydrophobicity of silica aerogels could be maintained up to 350℃. With increasing heating temperature, hydrophobicity decreased, and became completely hydrophilic after heat-treatment at 500℃. Brunauer-emmitt-teller (BET) surface area results indicated that the specific surface area of silica aerogels increased with increasing heating temperature in the range of 150-500℃. The effects of heat-treatment on the morphology and chemical bonding state of silica aerogels were investigated by scanning electron microscopy (SEM), differential temperature analysis (DTA) and Fourier-transform infrared spectroscopy (FT-1R).
Silica aerogels were prepared at ambient drying by using ethanol / trimethylchlorosilane (TMCS) / heptane solution as pore water exchange and surface modification of the wet gel before drying. The resulting silica aerogels exhibit a sponge-like structure with uniform pore size distribution. The effects of heat-treatment on the hydrophobicity, specific surface area and other properties were investigated. The results indicated that the hydrophobicity of silica aerogels could be maintained up to 350 ° C. With increasing heating temperature, hydrophobicity decreased, and became completely hydrophilic after heat-treatment at 500 ° C. Brunauer-emmitt-teller (BET) surface area results indicated that the specific surface area of silica aerogels increased with increasing heating temperature in the range of 150-500 ° C. The effects of heat-treatment on the morphology and chemical bonding state of silica aerogels were investigated by scanning electron microscopy (SEM), differential temperature analysis ( DTA) and Fourier-transform infrared spectroscopy (FT-1R).