Polyoxymethylene/graphene oxide-perfluoropolyether nano-composite with ultra-low friction coefficient fabricated by formation of superior interfacial tribofilm

The hybrid of graphene oxide nanosheets (GO)-perfluoropolyether (PFPE) was prepared, and polyoxymethylene (POM)/GO-PFPE nano-composite with ultra-low friction coefficient was fabricated via convenient melt processing. POM/PFPE molecules intercalated into GO layers by forming hydrogen bonding with high intercalation ratio and layer thickness, while GO was embedded and homogeneously distributed in matrix by incorporating PFPE as compatibilizer. Compared with neat POM, addition of GO-PFPE resulted in remarkable improvement of tribological behaviors with reduction of friction coefficient and wear rate by 65.2% and 74.4%, respectively, while the worn surface displayed flat and smooth features. The fluorine (F) element migrated towards sample surface to form uniform GO-PFPE transfer tribofilm and even reacted with iron (Fe) to form FeF2 at friction interface during rubbing process, which effectively inhibited direct surface contact of POM matrix with friction pair, and greatly reduced friction force and friction heat, resulting in excellent lubricant and anti-wear performance of the composite.