Fast-Dissociative and Slow-Associative Dual Dynamic Bonds Enable Self-Healing and Recyclable Polyethylene Networks for Sustainable High-Voltage Cable Insulation

Thermoset cross-linked polyethylene (XLPE) with a three-dimensional network structure exhibits high-temperature resistance and excellent insulating properties and is widely used for power cables. However, the permanent covalent cross-linked network leads to difficulties in self-healing and recycling after thermoelectric stress damage. Hence, the development of high-performance and ecofriendly XLPE insulation remains a challenging task. Here, two completely distinct dynamic covalent chemistries, fast-dissociative disulfide bond exchange and slow-associative ester exchange reaction, are combined in a polyethylene network to obtain a novel polyethylene covalent adaptable network (PE CAN). The synergistically regulated dynamic reaction rate enables the efficient self-healing and recyclability of PE CANs without compromising mechanical and insulating properties. In particular, the self-healing efficiency reaches 100% after both mechanical damage and corona damage. After three mechanical recycling cycles, the mechanical and insulation properties still reach the original levels. Moreover, the designed structures of PE CANs enhance the breakdown strength to 325.9 kV/mm and reduce electric field distortion to only 9.7% at 50 kV/mm and 70 °C by building deep traps. Therefore, combining associative and dissociative dynamic covalent bonds resolves the contradiction between high performance and sustainability of XLPE, pointing the way to the next generation of high-voltage direct-current cables.