Fabrication of dynamically cross-linked polyethylene with boronate ester bonds via a thiol–ene click reaction: thermal stability and reprocessability

Abstract

Cross-linked polyethylene (XLPE) is one of the most widely used thermosetting plastics today, valued for its excellent properties that enable broad applications. However, its permanently cross-linked three-dimensional structure makes it difficult to recycle after use, leading to a series of environmental and health concerns. Herein, we report a dynamically cross-linked polyethylene prepared via a click reaction between a cross-linking agent BDB (containing boronate ester bonds and two thiol groups) and the double bonds of the ethylene–butadiene copolymer. Benefiting from the thermal stability of boronate ester bonds, the material retains the high thermal stability (T_d5% is around 427 °C) of the ethylene–butadiene copolymer (T_d5% = 430 °C). This dynamically cross-linked polyethylene not only possesses the excellent mechanical (σ_m = 23.44 MPa) and thermal properties of traditional XLPE but also exhibits outstanding reprocessability (retains >70% of its performance after being reprocessed three times), offering a simple and efficient strategy for the sustainable utilization of XLPE. This approach fully aligns with the core principles of sustainable development.