Synergistic Liquid Metal-Diamond-Reinforced Poly(ionic liquid) Composites for High Thermal Conductivity and Excellent Reliability

This study presents a thermally conductive composite material that combines poly(ionic liquid) (PIL) poly(1-octyl-3-vinylimidazole)bis(trifluoromethanesulfonyl)imide (P[OVIm]NTf₂), liquid metal (LM), and diamond as dual fillers, totaling 85 vol % loading. The composite achieves a thermal conductivity of 14.2 W m^–1 K^–1, a tensile elongation of 74%, and an interfacial adhesion strength of 0.99 MPa on steel substrates. Structural optimization and interfacial engineering contribute to its exceptional mechanical flexibility and processability, confirmed by dynamic rheological analysis. In chip packaging tests, the composite enhances heat dissipation efficiency by reducing interfacial thermal resistance. Diamond incorporation prevents LM oxidation, maintaining 99% surface coverage and minimal performance degradation after aging tests (−55 to 125 °C, 300 cycles; 150 °C, 1000 h). Chromium-plated diamond further improves reliability under high humidity and temperature. This ternary system resolves the trade-off between high filler loading and flexibility in thermal interface materials. Interfacial reinforcement and synergistic stabilization mechanisms balance thermal conductivity with long-term reliability. These findings promote the use of poly(ionic liquid)s in thermal management, offering a durable solution for high-power electronics, especially in extreme conditions. The study establishes a framework for designing advanced TIMs with optimized performance and stability.