Macrotribology of semirigid poly(α- methylene- γ - butyrolactone) and poly(methyl methacrylate) brushes

A surface-tethered brush film of bio-based polymer, poly(α-methylene-γ-butyrolactone) (PMBL), was fabricated on a silicon wafer by surface-initiated atom transfer radical polymerization of α-methylene-γ-butyrolactone (MBL), which is a biomass monomer extracted from plants. The PMBL brush films formed a smooth surface. The surface free energy of the PMBL brush films was higher than that of the poly(methyl methacrylate) (PMMA) brush films because of the absence of hydrophobic methyl groups in the polymer backbone. The PMBL brush films exhibited a larger elastic modulus and better wear resistance than the typical structurally analogous petroleum-based PMMA brush films due to the high graft density and molecular interaction between PMBL chains.