Supramolecularly driven segregated graphene networks in polymer composites for electrothermal self-healing and damage sensing

Conventional thermally activated self-healing polymers often require external heating and lengthy recovery times for structural repair, as heat is transferred relatively inefficiently through convection. To overcome these limitations, Joule heating integrated through a percolated conductive filler network can be successfully employed. However, efficient electrothermal conversion requires the robust development of a highly conductive network within the polymer composite matrix. This study introduces a graphene/ureidopyrimidinone-functionalized poly(ε-caprolactone) (UBNP-G) composite that achieves rapid self-healing via electrical Joule heating. A segregated conductive network, formed through the interplay between the two-dimensional geometry of graphene and dynamic supramolecular interactions, exhibits exceptional electrical conductivity (10²–10⁴ times higher than that of one-dimensional UBNP–carbon nanotube composites at equivalent filler loadings). In contrast to one-dimensional fillers that remain randomly dispersed, graphene induces a phase-separated conductive network within the supramolecular polymer matrix. Molecular dynamics simulations support the distinct filler–polymer interactions responsible for the formation of the segregated network. Monitoring electrical resistance through the polymer composite provides a reliable measure of structural damage and recovery. Passing electrical current through the segregated network enables rapid self-healing within approximately 40 s at both room temperature and extremely low temperatures, without the need for external heat. These advancements present an effective strategy for designing multifunctional polymer composites for self-healing and structural health monitoring under diverse environmental conditions. During the review of the proof, we noticed that a critical statement regarding author contributions was omitted. Please add the following equal contribution note to the author information section or as a footnote on the first page: "Ohnyoung Hur, Yeong Jun Yu, and Ji-Hwan Ha contributed equally to this work."