Improved healability for large‐sized electrical breakdown in thermosetting polythiourethane with excellent mechanical properties and electrical insulation

Abstract Replacing thermoset insulation by healable and recyclable covalent adaptable networks is a promising approach to the sustainable development of electrical and electronic devices. However, the repair performance gifted by dynamic covalent bonds always conflicts with the excellent mechanical properties gifted by stiff cross‐linked networks. In this paper, by introducing dynamic thiocarbamate bonds, polythiourethane (PTU) with excellent mechanical properties and electrical insulation comparable to commercial epoxy resins are successfully developed, which exhibit superior healability and recyclability properties. Sub‐centimeter scale electrical breakdown failures of the PTU samples could be efficiently self‐healed with a healing efficiency up to 90%, while the storage modulus and volume resistivity exceeded 2 GPa and 10 16 Ω cm, respectively. Even though the electrical breakdown strength inevitably declined after multiple repair processes, PTU samples could restore their initial excellent insulation performance by simply reprocessing with the efficiency above 95%. Moreover, the efficient healability performance of large‐sized electrical breakdown failures remained after the reprocessing. These outstanding characteristics underscore the tremendous potential of PTU materials as a new generation of sustainable high voltage insulation.