Influences of VTMS/SiO2 ratios on the contact angle and morphology of modified super-hydrophobic silicon dioxide material by vinyl trimethoxy silane

Abstract

Vinyl trimethoxy silane (VTMS) was used as a modifier and strong ammonia was used as a pH regulator to prepare modified SiO2 superhydrophobic composites. VTMS was successfully in-situ grafted onto the surface of SiO2 via chemical modification. A contact angle detector, laser particle sizer, X-ray diffractometer, Fourier transform infrared spectroscope, scanning electron microscope, and thermogravimetric analyzer were employed to investigate the influence of the amount of VTMS on the hydrophobicity, crystal structure, surface microstructure, particle size, and grafting rate of the obtained SiO2 composites. The results show that VTMS can modify SiO2 within a short time to achieve superhydrophobic SiO2 powder with an interesting dual microstructure. The VTMS/SiO2 ratio has an obvious influence on the water contact angle and on the micro-double structure of the modified SiO2 powder, while the reaction time and the drying time have little effect on them. When the VTMS/SiO2 ratio was 10:1, the static contact angle of the modified SiO2 reached the maximum value of 154° (greater than 150°), and the rolling angle of 4° (far less than 10°) was sufficiently small to meet the requirements of superhydrophobicity. The particle sizes of the modified nano-SiO2 were distributed uniformly and the grafting rate of VTMS onto the SiO2 surface was satisfied. Keywords: Silicon dioxide, Vinyl trimethoxy silane (VTMS), Superhydrophobicity, Dual microstructure, Surface morphology