超疏水介孔二氧化硅气凝胶的常压制备与性能表征

SYNHESIS AND CHARACTERIZATION OF SUPERHYDROPHOBIC MESOPOROUS SILICA AEROGELS BY AMBIENT PRESSURE DRYING

以正硅酸乙酯(tetraethyl orthosilicate,TEOS)为原料,通过酸(草酸)-碱(氨水)两步催化,采用溶胶-凝胶法常压干燥制备了超疏水型介孔SiO2气凝胶。结果表明:当TEOS、乙醇、草酸、氨水的摩尔比为1:4:5:0.2,草酸和氨水的浓度分别为0.008,0.5mol/L时,制备的SiO2气凝胶堆密度为0.3503g/cm3,比表面积为765.27m2/g。透射电镜、扫描电镜、粉末X射线衍射和Brunauer-Emmett-Teller测试表明:SiO2气凝胶具有非晶纳米介孔结构。接触角测定和Fourier转换红外光谱分析表明:SiO2气凝胶表面的羟基被甲基取代,与水的接触角为152.1°,表现出超疏水性。

Superhydrophobic mesoporous silica aerogels were prepared by two step （acid-base） sol-gel process using tetraethyl orthosilicate （TEOS） as precursor followed by ambient pressure drying. Silica aerogels were prepared by keeping the mole ratio of 1：4：5：0.2 for TEOS, EtOH, oxalic acid, NH3-H2O with oxalic acid and aqueous ammonia concentrations fixed at 0.008 mol/L and 0.5 mol/L, respectively. By varying the solvent and surface modification, the density and specific surface area of silica aerogels are 0.350 3 g/cm^3 and 765.27 m^2/g, respectively. The silica aerogels were analyzed with transmission electron microscopy, scanning electron microscopy, X-ray diffraction and Brunauer-Emmett-Teller analysis. The results show that silica aerogels have an amorphous nano-porous structure and the pore diameter is in the mesoporous range. Contact angle test and Fourier transform infrared spectra show that the hydroxyl groups on the surface of the silica aerogels are replaced by methyl groups and the contact angle is 152.1 °. The results suggest that the aerogels are superhydrophobic.