Research On Adhesion And Stability Of Silicone Coating On Nanostructured Polycarbonate Fabricated By Hot Embossing

Polycarbonate(PC)transparent parts are widely applied to aerospace,national defense and other fields.PC with surface film can improve the protective performance or give new functions to the products.However,PC/film transparent parts are prone to adhesion failure in complex environments,which affects the safety and stability of the plastic parts.Surface modification is an effective way to improve the interface performance between substrate and film.Research and development of new surface modification methods,to explore its effect on the interfacial adhesion of PC/film system,as well as the effect on the stability of the product in harsh conditions,has important research significance and engineering value.In this paper,the nanopillar arrays of different sizes on the surface of PC(hereinafter referred to as micro-nano modification,Nano-PC)by hot embossing with porous anodized aluminum oxide(AAO)as a template were fabricated.Moreover,the effect of nanopillar arrays on the performance and structure of PC was investigated.For the silicone coating system(hereinafter referred to as Silicone),the correlation mechanism between the interface adhesion properties and the failure mode of Nano-PC/Silicone and UVC pretreatment-PC/Silicone was explored.Furthermore,the adhesion performance and stability of PC/Silicone system under severe conditions such as ultraviolet radiation,hydrothermal aging and cyclic bending were also analyzed.The main works are as follow:1.The effects of hot embossing process parameters and demolding methods on the replicativity of nanopillar arrays on PC surface were investigated.The results showed that the molding quality of nanopillar arrays on PC surface improved with the enhancement of hot pressing temperature and pressure.The direct stripping method was superior to the chemical etching method,because the tensile strength and fracture toughness of PC nanopillars were large enough,and the surface quality would not affected when the AAO template is directly stripped.2.Comparing surface micro-nano modification with UVC pretreatment,the effects and mechanism on the adhesion properties of PC/Silicone interface were investigated.The results showed that the interface micro-nano modification could significantly improve the adhesion performance of the Nano-PC/Silicone system.There were two failure modes of nanopillars fracture and coating fracture with the size change of interface nanopillars.Compared to improvement adhesion of the chemical bonding by UVC pretreatment,micro-nano modification mainly improved the interface performance by increasing the mechanical locking effect,and the adjustability was strong.3.The evolution of structure properties and the stability of the PC/Silicone system under severe conditions such as ultraviolet irradiation,hydrotherrmal aging and cyclic bending were investigated.The results showed that the Nano-PC/Silicone system exhibited better stability in various operating environments(without cracking or blistering of coating on PC surface).The main reason was that the interface of the system combined tightly and had better interface adhesion performance,which contributed to improve the resistance to environmental aging and stress,thereby improving the stability of the PC/Silicone system.