Stretchable, self-healable integrated conductor based on mechanical reinforced graphene/polyurethane composites

Abstract

Stretchable conductors are susceptible to wear through repeated deformation over time. Stretchable conductors with self-healing properties can increase longevity and reduce safety hazards. However, most current self-healing conductors can only repair either the conductive layer or the insulating layer. Meantime, high mechanical robustness and self-healing efficiency are exclusive especially at ambient conditions. Realizing a stretchable conductor with integral self-healing and ultra-high mechanical strength is challenging, because this requires good interfacial compatibility and adaptability of the conductive and insulating layers. We adapt a biphasic dynamic network strategy to add toughness to self-healing materials. The DOU (dimethylglyoxime–urethane polyurethane) dynamic bonds and hydrogen bonds in the soft phase enable high self-healing efficiency, while the graphene as a hard phase supports the material’s superior mechanical properties. We have prepared an overall self-healing stretchable conductor through the soft phase as a self-encapsulating insulating layer. This all-solid (Tg = -49.5 °C) graphene/dimethylglyoxime–urethane polyurethane (Gr/DOU-PU) composites characteristic of both high mechanical strength (~6 MPa, ~1000%, ~48 MJ m−3), self-healing conductivity (~90%, 10 min, 25 °C) and conductivity (R□=47.8 Ω □-1, d = 0.4 mm). The conductor has excellent stability for flexible electronics and for building stress sensors.