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

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。用傅立叶变换红外光谱(FTIR)、X射线衍射(XRD)、热重-差示(TG-DSC)、场发射扫描电镜(F-SEM)和比表面积(BET)等检测手段对样品的结构、形貌和性能进行了表征。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,使制备周期从原来的6d缩减到3d,不仅缩短了周期,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。

In this paper,a new method to produce hydropbic silica aerogels was introduced.SiO2 alcogels were prepared by tetraethoxysilane（TEOS） via the two-step acid-base sol-gel process,then the solvent was exchanged and the surface was modified by ethanol/hexmethyldisilazane/hexane,and finally dried at the ambient pressure.The structure,appearance and properties of the silica aerogels have been investigated by FTIR,XRD,TG-DSC,F-SEM,BET.Results showed that the one-step solvent exchange and surface modification process can reduce the time.The aerogels have a high surface area,which can be as high as 842.63 m2/g.The density of the aerogels is low（130 kg/m3）,the diameter of the particle size is about 15 nm.the diameter of the pore sizes is in the range of 2～170 nm.The aerogels show an excellent hydrophobic feature.