Abstract: Flexible silica aerogels having excellent flexibility, which solves the problems of easy breakage and poor formability, have received extensive attention. However, most flexible aerogels’ skeletons show fragile connections like pearl chains with a low cross-linking degree, which results in poor mechanical properties. In this paper, silica sol is introduced into the dual precursor system of methyltriethoxysilane and dimethyldiethoxysilane. Because of large amounts of-OH groups on nano-SiO2 particles in silica sol, a large number of nucleation sites were provided during the gel process, thus enhancing the crosslinking degree of aerogels and refining the size of secondary particles. The results show that compared with the aerogel without silica sol, the aerogel secondary particles with silica sol change from smooth spherical to fine irregular, and the average size decreases from 3.80 μm to 0.36 μm. The connection between the fine particles is tighter, which avoids the "necked" weak connection between spherical particles. The flexible silica aerogel prepared in this paper can withstand 80% compression and its morphology can be completely recovered after unloading. It can withstand more than 20 cyclic compressions with a strain of 60% and more than 50 cyclic adsorptions of organic pollutants. It also has good cyclic compression performance and cyclic adsorption performance. The flexible silica aerogel shows excellent hydrophobicity (surface contact angle up to 162.4°) and adsorption performance of organic pollutants (the adsorption capacity of n-hexane is 9.57 g/g). The flexible silica aerogel also has good thermal stability, and the maximum degradation rate temperature can reach 501.2 ℃ in a dry air environment.
王丽丽, 唐杰, 秦陆洋, 李雪莎, 聂朝胤. 基于硅溶胶形核剂的柔性二氧化硅气凝胶的研究[J]. 材料导报, 2023, 37(24): 22080230-6.
WANG Lili, TANG Jie, QIN Luyang, LI Xuesha, NIE Chaoyin. Study on Flexible Silica Aerogel Based on Silica Sol Nucleating Agent. Materials Reports, 2023, 37(24): 22080230-6.
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