Surface hydrophobic modification of ultra-fine aluminum silicate by mechanically grinding and heating

Highly hydrophobic ultra-fine aluminum silicate can be obtained by mechanically grinding and heating both aluminum silicate particles and octadecoic acid. The results showed that the organic modifier was adsorbed on the surface of aluminum silicate particles where a little new organic group was generated, and the hydrophobicity of ultra-fine aluminum silicate powder was enhanced. Grafting reaction was mainly carried out in heating process. Due to both grinding and heating, the modifier spread on the surface of particle completely and bonded with Si to form Si–O–C, and with Al to form acyl alumina in bidentate coordination. As a result, a highly hydrophobic layer was formed on the powder surface. However, it was unsuitable for heating temperature to exceed 180 °C, or else the layer would be destroyed. All the above points represent a useful effort for surface-grafting modification of powder particles. In this study, a novel method as a reference was provided on the surface-grafting modification of powder particles.