大块SiO_2气凝胶的制备及疏水性能的研究

Preparation and hydrophobic performance of block silica aerogels

以廉价工业水玻璃为原料,乙二醇为干燥控制化学添加剂,三甲基氯硅烷为表面改性剂,醋酸为催化剂,通过溶胶凝胶法和常压干燥技术制备出SiO2气凝胶。采用XRD、SEM和FT-IR等方法研究了醋酸浓度对SiO2气凝胶结构的影响,以及表面改性对其疏水性能的影响。结果表明:SiO2气凝胶为典型的无定型非晶态,呈现疏松多孔三维网络纳米结构。采用浓度为1.2mol/L的醋酸进行催化时,得到大块不开裂SiO2气凝胶,其表观密度为0.22g/cm3,孔隙率高达90%。当用三甲基氯硅烷对气凝胶表面进行疏水处理后,凝胶骨架表面接上了硅甲基,表现出较好的疏水性。

Block silica aerogels were prepared by way of sol-gel process and drying under ambient pressure with industrial water glass as silica source,glycol as drying control chemical agent（DCCA）,trimethylchlorosilane（TMCS）as surface modifier and acetic acid as hydrolysis.The effects of concentration of acids on the structure and hydrophobic performance of areogels were investigated by means of X-rat diffraction（XRD）,scanning electron microscopy（SEM）and fourier infrared（FT-IR）.The results indicated that the aerogels were typical amorphous and showed porous three-dimensional network nanostructure.The block silica aerogels were obtained when the acetic acid was 1.2mol/L,and the density and porosity were 0.22g/cm3 and 90%,respectively.When the surface of aerogels were modified by TMCS,the silicon methyl was linked on the skeleton of aerogels,and the aerogels showed apparent hydrophobicity.