Covalently Functionalized Leakage-Free Healable Phase-Change Interface Materials with Extraordinary High-Thermal Conductivity and Low-Thermal Resistance

Phase-change materials (PCMs) have received considerable attention to take advantage of both pad-type and grease-type thermal interface materials (TIMs). However, the critical drawbacks of leaking, non-recyclability, and low thermal conductivity (kappa) hinder industrial applications of PCM TIMs. Here, leakage-free healable PCM TIMs with extraordinarily high kappa and low total thermal resistance (R-t) are reported. The matrix material (OP) is synthesized by covalently functionalizing octadecanol PCM with polyethylene-co-methyl acrylate-co-glycidyl methacrylate polymer through the nucleophilic epoxy ring opening reaction. The OP changes from semicrystalline to amorphous above the phase-transition temperature, preventing leaking. The hydrogen-bond-forming functional groups in OP enable nearly perfect healing efficiencies in tensile strength (99.7%), kappa (97.0%), and R-t (97.4%). Elaborately designed thermally conductive fillers, silver flakes and multiwalled carbon nanotubes decorated with silver nanoparticles (nAgMWNTs), are additionally introduced in the OP matrix (OP-Ag-nAgMWNT). The nAgMWNTs bridge silver-flake islands, resulting in extraordinarily high kappa (43.4 W m(-1) K-1) and low R-t (30.5 mm(2) K W-1) compared with PCM TIMs in the literature. Excellent heat dissipation and recycling demonstration of the OP-Ag-nAgMWNT is also carried out using a computer graphic processing unit. The OP-Ag-nAgMWNT is a promising future TIM for thermal management of mechanical and electrical devices.