Fabrication of high-strength and self-healing polyurethane composites <i>via</i> Diels–Alder dynamic bonds for sustainable thermal management materials

Electronic devices generate a large amount of heat, which can damage devices if not dissipated in a timely manner. Thermal interface materials (TIMs), which are used to enhance heat dissipation efficiency, face challenges in simultaneously achieving high thermal conductivity, desired mechanical properties, and remarkable adhesive, self-healing and recycle properties. In this work, we successfully synthesized a series of dynamically reversible polyurethane (DRPU) elastomers <i>via</i> a Diels-Alder (DA) reaction to serve as TIM matrices. DRPUs demonstrated excellent mechanical properties, with a tensile strength of 35.8 MPa, an elongation at break of 714% and a toughness of 146.07 MJ m^-3. Owing to the synergistic effects of dynamic covalent interactions and strong intrinsic cohesion, DRPUs exhibited a good lap-shear strength of 3.3 MPa on aluminum plates. Additionally, DRPUs displayed efficient self-healing properties, with a self-healing efficiency of 87% that remained at 78% after multiple healing cycles. Furthermore, pre-prepared polydopamine-modified Al₂O₃(f-Al₂O₃) was confirmed to increase the thermal conductivity of DRPUs.