Abstract：In order to obtain hydrophobic nano-SiO2 inorganic fillers, three kinds of long-chain silane coupling agent, octyl, dodecyl, and hexadecyl triethoxysilane were used to prepare hydrophobic nano-silica under anhydrous condition. The structure of the product was characterized by IR, TEM and BET. The hydrophobic effect of nano-sized SiO2 particles was investigated by the wettability, free surface energy of solid and organic compatibility. The results shows that after surface modification, the nano-silica particles change from strongly hydrophilic to strongly hydrophobic, the aggregation decreases obviously, the free surface energy decreases significantly, and the organic compatibility highly increases. Among them, by optimizing the process parameters, the optimum mass ratio of modifier to nano-SiO2 is 2∶1 and the maximum hydrophobic angle is 145.36%°.In addition a 'wetting regulation' mechanism of structure control performance is drew in this paper.

Keywords：silane coupling agent; hydrophobic; modification; wetting regulation