溶胶凝胶一步溶剂交换与表面改性制备疏水硅气凝胶

Hydrophobic silica aerogels prepared by sol-gel one-step solvent exchange and surface modification process

摘要:

摘要：本文以正硅酸乙酯为硅源，采用酸碱两步催化的溶胶-凝胶法，以无水乙醇∕六甲基二硅氮烷∕正己烷为溶剂交换与表面改性试剂，通过一步溶剂交换与表面改性和常压干燥工艺制备疏水sio2气凝胶。采用傅立叶转换红外线光谱(FTIR)、X射线衍射(XRD)、热重-差示 (TG-DSC)、场发射扫描电镜(F-SEM)和比表面(BET)等检测手段对样品的结构、形貌和性能进行了表征。实验结果表明：将传统的溶剂交换与表面改性由多个步骤改为一步完成，制备周期从原来的6天缩减到3天，不仅降低了能耗，而且使所得的sio2气凝胶样品具有842.63m2/g的高比表面积、130kg/m3的低密度、15nm的超细颗粒、2～170nm的孔洞结构和良好的疏水性能。

Abstract:

Abstract: In this paper, a new method to produce hydropbic silica aerogels was introduced. SiO2 alcogels were prepared by tetraethoxysilane (TEOS) via two-step acid-base sol-gel process,then the solvent was exchanged and surface was modified by ethanol/hexmethyldisilazane/hexane, and finally dried at ambient pressure. The structure，appearance and properties of the silica aerogels have been investigated by FTIR, XRD, TG-DSC,F-SEM, BET. The results showed that one-step solvent exchane and surface modification process can reduce the time from 6 days to 3 days , the aerogels have high surface area,can be as high as 842.63m2/g. The density of the aerogels is low(130kg/m3),the diameter of particle size is about 15nm.the diameter of the pore sizes is in the range of 2-150 nm.The aerogels show an excellent hydrophobic feature.