恒沸蒸馏超细SiO2凝胶的二甲基二氯硅烷表面改性研究

利用恒沸蒸馏快速置换出SiO2湿凝胶中的物理吸附水，并用二甲基二氯硅烷（DMDCS）进行湿法改性。通过透射电子显微镜（TEM）、红外光谱（FT-IR）、热重-差热（TG-DTA）、激光粒度分析仪和接触角测定仪等表征方法研究了DMDCS的改性效果。结果表明，将恒沸蒸馏用于SiO2湿凝胶的表面改性，能得到疏水性能极佳的改性SiO2，水在改性SiO2粉体表面的接触角大于130°，改性产品蓬松，吸油值增大2~2.8，孔容增大3.5倍，孔道结构没有发生显著改变。优化了的改性工艺为：改性溶剂为体积比3∶2的丙酮、乙醇混合物，改性时间2h，改性剂用量为SiO2绝干粉质量的12.5%。

Surface modification by dimethyldichlorosilane of ultra-fine silica gel dried by azeotropic distillation

Physically absorbed water in wet silica gel was rapidly removed by azeotropic distillation, and the dry silica gel was subsequently treated with dimethyldichlorosilane (DMDCS) to prepare hydrophobic silica. The resulting material was characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), differential thermal analysis (TG-DTA), laser particle size analysis and contact angle measurements in order to investigate the effects of modification. It was found that the modified silica had excellent hydrophobic properties, with the contact angle between modified silica and water being greater than 130°. After modification of the silica, the product appeared fluffy, the di-n-butyl phthalate (DBP) oil absorption value significantly increased, the proportion of larger pores increased, whilst the pore structure showed no significant change. The optimal modification conditions were found to involve a mixture of acetone and ethanol in the volume ratio 3:2, a modification time of 2h, and a modifier content of 12.5% of the weight of silica.