Sol-Gel Preparation of HTMS-Silica Hydrophobic Coatings with High Environment-Resistance

The monodisperse colloidal SiO2 sol was prepared by sol-gel process using tetraethyl orthosilicate (TEOS) as precursor and ammonia as catalyst. Hexadecyltrimethoxysilane (HTMS) as a modifier was added into the sol to passivate the surface of the silica particle. Silica antireflective (AR) coatings were then prepared from different SiO2 sols by a dip-coating method. UV-Vis-NIR spectrometer, Fourier transform infrared spectroscopy, transmission electron microscope, scanning electron microscope and water contact angle measurement were employed to analyze the optical property, microstructure, surface morphology and environmental stability of the coatings. The results show that the HTMS modified silica AR coatings can achieve a high transmittance of 99.8% and possess excellent environment stability. After they have been placed in an ambient with relative humidity higher than 90% for 2 months, the peak transmittance of the silica AR coatings modified with HTMS decreases only by 0.3%.