Enhancing durability of concentrated polymer brushes using microgrooved substrates

Abstract Concentrated polymer brushes (CPBs) are swollen polymeric materials promising for tribological applications owing to their ultralow friction. However, their insufficient durability has limited their practical use. In this study, to improve the durability, poly(methyl methacrylate) CPBs fabricated on microgrooved substrates were experimentally investigated in two types of tests (i.e., “sliding tests” and “nanoindentation tests”). Sliding tests revealed that parallel grooves with adequate dimensions significantly improve their durability in lubricated sliding. Nanoindentation tests revealed that the CPB on a flat substrate exhibits a layered structure comprising two layers (i.e., a “diluted surface layer” and a “concentrated bulk layer”). An additional third layer (i.e., a “reinforced tough layer”) provided by the parallel grooves appears to improve the durability.