Scratch Behavior of Micro-Patterned Polymeric Surfaces

Abstract

Polymers are inherently scratch-sensitive due to their ease of deformation and damage. Polycarbonate (PC) offers excellent optical clarity and mechanical resilience, yet has limited engineering usage due to its vulnerability to surface scratching. Utilizing patterned surfaces while maintaining transparency is a viable strategy to achieve improved scratch resistance of PC. In this study, effect of micro-imprinted surface patterns, specifically, 10 µm holes and pillars, on the frictional and scratch behavior of PC was investigated using a combined experimental and finite element methods (FEM) approach. Standardized scratch tests (ASTM D7027-20/ISO 19252:08) and high-resolution confocal microscopy were chosen to assess damage resistance, while the dynamic stress distribution and contact area evolution during scratching were captured via FEM. Results demonstrate that hole-patterned surfaces exhibit superior scratch resistance compared to pillar-patterned and flat surfaces. This improvement is attributed to the reduction in contact area, lower coefficient of friction, and a possible “air cushion” effect generated by the trapped air within the holes, which provides additional resistance. Although pillar structures initially reduce the friction coefficient, they are prone to early mechanical failure due to stress concentration. This study presents a predictive mechanistic framework that extends the existing literature by incorporating fluid–structure interaction effects, offering a promising avenue for designing scratch-resistant polymers.