Dynamic covalent chemistries of thermosetting polymer for recyclability and intelligent lubrication

Recently, the focus of materials research has shifted toward intelligent materials and structures with customizable properties and stimulus-responsive functions. Here, a recyclable thermosetting epoxy resin with self-reported wear and customizable friction is achieved through dynamic and reversible molecular structure design. The epoxy vitrimer displays exceptional mechanical properties, with a Young’s modulus of 2.3 GPa, elongation at break of 7.1%, and tensile strength of 79.25 MPa. Based on the reversible exchange of dynamic covalent bonds, the epoxy vitrimer can be fully recovered through hot pressing without the need for additional adhesives or catalysts, and even self-healing can be achieved. Furthermore, by utilizing the reversibility of dynamic covalent bonds, nanofillers (graphene oxide (GO) and polytetrafluoroethylene (PTFE)) with specific tribological properties are incorporated into the recovery process to achieve customizable friction coefficients and wear rates. The self-reported characteristics of wear based on sulfur radicals are realized by exploiting the dynamic nature of disulfide bonds. The correlation between wear time and wear state is investigated. The molecular structure design of epoxy based on dynamic covalent bonds has resulted in a versatile thermosetting material with self-reporting and customizable friction properties that is ideal for sustainable engineering and friction applications. This enables intelligent manufacturing while reducing resource waste.