疏水性二氧化硅气凝胶性能表征

Characterization of hydrophobic silica aerogels properties

目前S iO2气凝胶是世界上最轻、隔热性最好、孔隙率较高且声传播速率较低的固体材料,由于其特殊的网络结构使其具有很多独特的性能,而制备疏水性气凝胶是解决常压干燥过程中体积收缩和开裂的关键.采用溶胶-凝胶法以三甲基氯硅烷(TMCS)为化学表面修饰剂通过衍生法制备了疏水性二氧化硅气凝胶,并利用X射线衍射光谱、扫描电镜、能量色散谱、透射电镜、红外光谱、差热-热重分析等测试方法对其结构、形貌及化学组成进行了分析.研究表明:该样品是表面连有疏水基团—CH3的疏水性S iO2气凝胶,且组成其连续网络结构的球状纳米粒子纯度较高、粒径均匀,是热稳定性较高的非晶、多孔、轻质纳米材料.

At present, aerogels are the lightest solid material. Because of their special structure they always have many unique properties： such as they have the best property in thermal insulation and have the higher po- rosity,the lower sound velocities in all solid materials and so on. But the key step to solve the shrinkage and crack during drying at ambient pressure is the preparation of hydrophobic silica aerogels. In the paper hydrophobic silica aerogels were prepared by sol-gel method with trimethylchlorosilane as the surface chemical modification via derivatization. The XRD, SEM, ED, TEM, IR and DTA-TG analysis were used to observe the structure, the surface morphology and the chemical composites of the sample. The results show that the samples are silica aerogels with the hydrophobic group methyl attaching to their surface, and the spherical nanometer particles which constitute the continual web structure of aerogels have higher purity and the diameter of particles is very even. They are non-crystallized,porous and light nanometer materials with higher thermal stability.