Low Contact Thermal Resistance without Packaging Pressure in Highly Thermally Conductive Interface Materials Enabled by Polysulfide Vitrimer

Thermal interface materials (TIMs) are essential for enhancing interfacial heat transfer, yet achieving both high through-plane thermal conductivity (κ_⊥) and structural conformability remains difficult. This study introduces a vitrimer-based TIM using a diglycidyl-ether end-capped liquid polysulfide prepolymer (EPS), where stress relaxation from dynamic covalent bonds improves interfacial contact. A vertically aligned graphite composite (VAGC) with high κ_⊥ (15.5 W m^-1 K^-1) was fabricated via a combined hot-pressing and "stacking-welding" method. Driven by unstable dynamics from a reversible topological network and high surface free energy of thermodynamic properties, VAGC exhibits spontaneous contact behavior. Under zero pressure, the contact thermal resistance drops sharply at 80-100 °C and reaches 16.4 mm² K W^-1, while the effective thermal conductivity of VAGC reaches 14.4 W m^-1 K^-1. It is believed that the novel EPS vitrimer offers a promising polymer matrix for advanced TIMs.