Plasma and chromic acid treatments of polycarbonate surface to improve coating-substrate adhesion

Ultrastable and Durable Silicone Coating on Polycarbonate Surface Realized by Nanoscale Interfacial Engineering

Delamination of coating layer from polymer substrate limits the lifetime and functionality of the protective films. Silicone coating is especially vulnerable to photo irradiation, hydrothermal degradation, and mechanical deformation due to the low interfacial adhesion and mechanical robustness. Herein, an ingenious approach is developed to fabricate ultrastable and durable silicone coating on polycarbonate (PC) substrate through well-controlled nanoscale interfacial engineering. A nanopillar array is fabricated on the PC surface by vacuum-assisted hot embossing using anodic aluminum oxide (AAO) templates. Significant improvement in interfacial shear strength (ISS) is achieved for the silicone coating on the nanostructured PC surface. The delamination mechanism can be controlled by tuning the nanopillar size, and the maximum ISS of 9.9 MPa was reached on a surface with a nanopillar diameter of 320 nm. Attributed to the increased interfacial area and mechanical interlocking structure, the nanostructured interface can effectively dissipate interfacial stress and prevent cracking; therefore, maintaining excellent transparency and performance in the harsh environment. The coating exhibits extraordinary stability and durability when subjected to UV irradiation for 168 h, hydrothermal aging for 120 h, mechanical bending for 1000 cycles, and even surface damage. Thus, the tough silicone coating on polymer substrate realized by nanoscale interfacial engineering is a promising technique for highly stable and durable transparent surface protection.