Characterization and tribological performance of new epoxy coatings modified with sustainable ionic liquid-graphene nanolubricants

Graphene-based nanolubricants were prepared using the environmentally friendly 2-hydroxyethylammonium lactate (ML) ionic liquid. The Graphene-ML dispersion (MLG) and neat ML were added to Epoxy Resin (ER) in 5 and 10 wt% proportions to study the effect on the curing conditions by means of Differential Scanning Calorimetry (DSC) and oscillatory rheology. A nucleating effect was found for Graphene, while ML presented a plasticizing effect. These findings were confirmed by DSC and Dynamic-Mechanical Analysis (DMA) with a decrease on the mechanical properties and glass transition temperature. ML and MLG were evaluated as external lubricants of epoxy coatings, finding outstanding friction and wear prevention ability. One and two layer ER coatings were deposited on AISI 1015 steel disks. When used as internal lubricant, MLG is able to prevent surface damage on bi-layer ER coatings. Therefore, we provide a novel approach for the preparation of ER composites with environmentally friendly nanolubricants for applications under demanding conditions.