疏水改性对SiO2气凝胶薄膜性能与结构的影响

以正硅酸乙酯(TEOS)为前驱体,采用溶胶-凝胶法制备SiO2气凝胶薄膜,并以不同体积分数的六甲基二硅胺烷(HMDZ)对SiO2气凝胶薄膜进行了疏水改性研究,采用椭偏仪、FITR、接触角测试仪、SEM和光谱仪等对薄膜的疏水性、微观结构及透光性进行了表征,研究了HMDZ疏水改性对SiO2气凝胶薄膜性能与结构的影响。结果表明,疏水改性后,SiO2胶粒表面的大部分亲水性-OH被疏水基团-CH3所取代,其与水的接触角达159°,疏水性好;SiO2气凝胶薄膜在可见光范围内透光率接近90%,透光性高;其孔隙率为78.8%,密度为0.464g/cm3,骨架颗粒尺寸小于40nm,具有纳米多孔网络结构特性。

Effect of Hydrophobic Modifying on the Properties and Structure of Silica Aerogel Films

Transparent hydrophobic silica aerogel films were successful prepared by using tetraethyoxysilane(TEOS) as silicon source and modified with various volume-concentration of hexamethyldisilazane(HMDZ) via Sol-gel process.Ellipsometry,FTIR,contact angle instrument,SEM and spectrometer were used to characterize the hydrophobic property,microstructure and transparence of silica aerogel films.The results show that hydrophilic-OH groups on the surface of silica particles have been mostly replaced by hydrophobic-CH3 groups,the contact angle between silica aerogel films and water droplet is up to 159°,which suggests that the films have excellent surface hydrophobicity.The percentage of transmission of silica aerogel films in the range of visible light reaches to 90%,which indicates that the films have good transparence.The sizes of particles in silica aerogel films are less than 40nm,the porosity is 78.80% and the density of the films is 0.464g/cm3.This is a typical nano-prous network structure.