Enhanced mechanical and tribological properties of epoxy composites reinforced by novel hyperbranched polysiloxane functionalized graphene/MXene hybrid

Two-dimensional graphene and Ti3C2Tx MXene have enormous potential in improving mechanical and frictional properties of the resin matrix. However, their easy re-stacking trend and poor interfacial adhesion in organic substance hinder practical applications. Herein, the lamellar reduced graphene oxide/MXene (RGO/MXene) hybrid functionalized with a series of Si-O-C hyperbranched polysiloxane (HBPSi-1, 2, 3) were successfully synthesized. The introduction of more side groups in HBPSi enhances the interfacial adhesion between nanofillers and epoxy (EP) matrix. The good lubricating function of lamellar RGO/MXene, excellent toughening effect of HBPSi due to its flexible chain segment and intermolecular cavities, and fine interfacial adhesion lead to the dramatically improved mechanical and frictional performance of EP composites. The results showed that the incorporation of moderate addition of HBPSi-3 modified RGO/MXene (H3RM) markedly enhanced the comprehensive properties of EP composites. Specifically, when the EP loaded with 0.7 wt% H3RM, the composites exhibited the highest impact and flexural strengths (33.2 kJ/m2 and 170.1 MPa). And 0.6 wt% H3RM/EP composite achieved dramatic reductions of 51.7% and 70.2% in the average frictional coefficient and volume wear rate. This work enlightens a brand idea for the design and application of RGO/MXene solid lubricant additive.