A graphene/polyurea composite with both thermal conduction and self-healing functions based on dual dynamic networks

The development of thermal conductivity materials that can be quickly repaired has attracted increasing attention. However, due to the trade-off between thermal conductivity and self-healing properties of materials, it is challenging to prepare thermal conductivity polyurea composites with self-healing properties. To solve this problem, this paper proposes to construct self-healing polyurea (D-PUA) flexible membrane by using the double dynamic network of hydrogen bonds and dynamic imine bonds. The dynamic breaking and reconstruction of hydrogen bonds and imine bonds dissipates energy continuously, which makes D-PUA have good elasticity and self-repair. The experimental results demonstrate that scratches on the D-PUA film can be completely repaired in a short time (60 ℃, 8 min), and the repair efficiency of tensile strength reaching 84.62% after 72 h of cutting and healing. The GNP/D-PUA composite membrane with self-healing, thermal conductivity and recyclability was prepared by incorporating graphene (GNP) as a filler. Due to the high thermal conductivity of graphene itself, the in-plane thermal conductivity of the composite film is 2.57 W·m⁻¹·K⁻¹ when the GNP content is 10 wt%, which is 571% higher than that of the pure film. GNP₁₀/D-PUA can also heal scratches at 90 ℃ for 60 min, and the repair efficiency of tensile strength after 72 h of cutting and healing is 83.94%. Additionally, due to the presence of dynamic bonds, there is no significant mechanical loss after five hot pressing remodeling of the composite film, and the repair rate of in-plane thermal conductivity is above 80.93% in all cases.