Fabrication of Dynamically Cross-Linked Polyethylene with Boronate Ester Bonds via 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 the 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 dynamic cross-linked polyethylene not only possesses the excellent mechanical (σm = 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.