Synthesis of SiO2/Organosilicone Hybrid Coating via Sol–Gel Method

Abstract: The transparent and hard SiO2/organosilicone hybrid coatings were prepared on polycarbonate (PC) with tetraethoxysilane (TEOS), methyltriethoxysilane, dimethyldiethoxysilane and 3-(methacryloxypropyl)-trimethoxysilane as the main raw materials by the sol–gel method. The structure and properties of the hybrid coating were characterized by Fourier transformed infrared, ultravio-let-visible spectroscopy, thermogravimetric analysis, X–ray diffraction, scanning electron microscopy, atomic mechanics microscope, contact angle measuring instrument, and hardness tester etc. It is found that the basic structure of the hybrid coating is Si—O—Si. After heat-cured at 120, the thickness of the hybrid coating is 0.84 ℃ µm by dipping-withdrawing manner. The hybrid coating is smooth, homogenous and densified, and can improve the transparency of PC (transmittance is increased by nearly 5%). The contact angle of the hybrid coating to the water increases with the increase of curing time. The contact angle is 93°after heat-cured at 120 ℃ for 3 h. The hybrid coating has excellent thermal stability, which increases gradually with the increase of TEOS content. When the mole ratio of R (organic groups) and Si in SiO2/organosilicone hybrid resin is 0.78, the adhesion strength of hybrid coating on PC sheet is 0 class (cross-cut tape test), and it reaches a pencil scratch hardness of 2H. Key words: sol–gel method; organosilicone; hybrid; polycarbonate; hard coatin