Embedding constructed refractive index graded antireflective coating with high abrasion resistance and environmental stability for polycarbonate glass

Polycarbonate (PC) is a durable and transparent optical plastic material commonly used as shatter-resistant alternative to traditional optical glass. Broadband antireflective (AR) coatings with excellent mechanical strength and environmental stability are essential for PC to achieve high light transmission and visual quality. In this work, chloroform vapor treatment was employed to partially embed the silica coating into the PC substrate for adhesion enhancement, which also divided the silica coating layer into bottom and middle layers with different refractive indices. The contact between the silica nanoparticles and the substrate was transformed from point-contact to area-contact, which enhanced the adhesion between coating and PC substrate. After the deposition of a top layer coating consisted of silica nanopar-ticles with smaller diameter, a triple-layer refractive index graded AR structure was constructed. Hexamethyldisilazane vapor surface modification was performed to decrease the surface free energy of top coating layer. The triple-layer coating coated PC exhibits superior antireflection property with an average reflectance of only 0.43% over a wide wavelength range of 400-1000 nm. After 100 times of fric-tion or 5 months of exposure to a contaminated environment, the reflectance of coated PC shows barely noticeable difference, indicating its excellent mechanical strength and environmental stability. (c) 2021 Elsevier Inc. All rights reserved.

Automated summary

In this study, a triple-layer coating with excellent antireflection properties was prepared using chloroform vapor treatment and hexamethyldisilazane vapor surface modification techniques. The results show that the triple-layer coating coated PC exhibits superior mechanical strength and environmental stability.