YANG Jing LIU Huahua

(School of Environment & Chemical Engineering, Xi'an Polytechnic University, Xi'an Shanxi 710048, China)

Abstract: The MTES -SiO₂ sols have been prepared by the sol -gel method using methyltriethoxysilane (MTES) as the hydrophobic precusor to methylated silica sol. The influence of MTES addition on the chemical structure and properties of silica sols were investigated. The results show that, with the increasing of MTES addition, the sol viscosity decreases, the gelation time increases and the particle size slightly increases. FTIR analysis shows that Si -O -Si bond is the primary structure of MTES -SiO₂ sol. Si -CH₃ group was introduced successfully into the MTES -SiO₂ sol and the formed silica molecules possess the line-typed structure. During the aging process of MTES -SiO₂ sol, the viscosity and solid contents have less change, and the sol particle diameter slightly increases before the viscosity sharply increases. With the close of the gel point, the silica molecules change gradually from line-typed to three-dimensional network structure.

Key words: silica sol; methyl-modification; viscosity; particle size; FTIR spectra