基于硅溶胶形核剂的柔性二氧化硅气凝胶的研究  

Study on Flexible Silica Aerogel Based on Silica Sol Nucleating Agent

作　　者：王丽丽[1] 唐杰[1] 秦陆洋 李雪莎 聂朝胤[1] WANG Lili;TANG Jie;QIN Luyang;LI Xuesha;NIE Chaoyin(School of Materials and Energy,Southwest University,Chongqing 400715,China)

机构地区：[1]西南大学材料与能源学院,重庆400715

出　　处：《材料导报》2023年第24期73-78,共6页Materials Reports

摘　　要：柔性二氧化硅气凝胶具有优异的柔韧性,解决了二氧化硅气凝胶易破碎、成形性差的问题,受到了广泛的关注。但是柔性二氧化硅气凝胶的骨架大多呈珍珠链状的脆弱连接,交联程度低,导致其力学性能较差。本工作在甲基三乙氧基硅烷、二甲基二乙氧基硅烷双前驱体体系中引入硅溶胶,利用硅溶胶中纳米SiO_(2)粒子提高形核密度,细化二次粒子尺寸,同时利用其表面富含的-OH基团为两种前驱体的水解产物提供大量的缩合位点,提高气凝胶的交联程度。结果表明,与未加入硅溶胶的双前驱体气凝胶相比,加入硅溶胶的气凝胶二次粒子由光滑的球形颗粒转变为细小的不规则形貌颗粒,平均尺寸由3.80μm减小为0.36μm。同时细小颗粒间的连接更加紧密,避免了球形粒子间的“颈缩”式弱连接。制备的柔性二氧化硅气凝胶可承受的压缩量达80%,卸载后其形貌可以完全恢复,并且可以承受20次以上应变为60%的循环压缩及50次以上的有机污染物循环吸附,具有良好的循环压缩性能和循环吸附性能。柔性二氧化硅气凝胶显示出优异的疏水性(表面接触角高达162.4°)与有机污染物吸附性能(对正己烷的吸附量为9.57 g/g)。同时,本柔性二氧化硅气凝胶还具有良好的热稳定性,在干燥空气环境下的最大降解速度对应的温度可达501.2℃。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-SiO_(2) 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.

关 键 词：疏水性 柔性气凝胶 油水分离 硅溶胶 

分 类 号：O648[理学—物理化学]