Synergistic effects of nitrogen-containing functionalized copolymer and silicon-doped DLC for friction and wear reduction

We present a strategy to enhance the tribological performances of diamond-like carbon (DLC) films based on synergistic chemical modifications in the polymer lubricant additives and in the carbon film. Our experiments revealed that the polymer functionalization with nitrogen-containing groups and the DLC doping with silicon atoms result in significant friction and wear reduction under severe boundary lubrication conditions. Atomic Force Microscopy revealed the formation of a lubricious tribofilm. Ab initio calculations highlighted the key role of N-Si interactions in promoting the polymer chemisorption on the film, which represents the first, essential step for the tribofilm formation. Our findings suggest that targeted chemical modifications in lubricants and films can substantially advance the tribological performances of DLC films for various industrial applications. • Nitrogen-functionalized copolymer and Si-doped DLC reduce friction and wear. • Formation of a lubricious tribofilm observed with Atomic Force Microscopy. • Ab initio simulations show DMAEMA forms N-Si bonds on Si-DLC surfaces. • N-Si interactions promote polymer chemisorption, crucial for tribofilm formation.