Multilayered Polyimide Nanocomposite Coatings for Enhanced Tribological Performance

Abstract This study reports the development and tribological evaluation of multilayered polyimide (PI) nanocomposite coatings to enhance both mechanical and tribological performance. A multilayer architecture was adopted, wherein a primer layer was introduced to improve adhesion between the substrate and the functional top layer, which directly influences tribological behavior. The composite coating exhibited significant reductions in wear volume as compared to pristine PI coating: 58.37% reduction at 2 N for GG_MM (base layer polyimide + graphene oxide, top layer MoS2 + Ti3C2Tx MXene), 50.84% at 4 N for GO–MoS2–MXene (GMM) (base layer and top layer polyimide + graphene oxide + MoS2 + Ti3C2Tx MXene), and 66.52% reduction at 2 N for GMGM coating. The incorporation of nanofillers led to increased hardness and elastic modulus of the polyimide matrix. This enhancement is attributed to functional groups on the nanoparticle surfaces, which facilitated chemical crosslinking with the polyimide chains, thereby restricting polymer chain mobility and suppressing plastic deformation. In contrast, nanoparticles lacking functional surface groups exhibited minimal influence on the mechanical properties. Tribological tests conducted under Hertzian contact pressures ranging from 0.21 to 0.31 GPa indicated that, with increasing load, plastic flow became the dominant wear mechanism, underscoring the load-dependent nature of the tribological performance.