PDMS/functionalized h-BN/liquid metal flexible composite with dual-network structure for achieving superior thermal conductivity and low thermal resistance via interfacial grafting

Thermal interface materials (TIMs) play a crucial role in addressing the heat dissipation challenges associated with high-power electrical equipment. Apart from possessing excellent thermal conductivity, and they must also exhibit low contact thermal resistance to facilitate efficient heat transfer at the interface. In this study, a novel composite with a dual-network structure was prepared by interfacial grafting to achieve superior thermal conductivity. The composite comprises polydimethylsiloxane (PDMS), functionalized boron nitride (f-BN), and liquid metal (LM). This dual network structure effectively enhances phonon transportation and significantly improves the thermal transport performance of the composite. The thermal conductivity of the obtained composite can achieve 4.4 W/m·K, accompanied by a low contact thermal resistance of 0.32 °C·cm2/W. Furthermore, the dual network structure ensures the flexibility of the composite, as evidenced by the maximum elongation reaching 267.43% at a tensile strength of 0.35 MPa. This exceptional mechanical performance is expected to alleviate stress concentration issues arising from thermal expansion mismatch, thereby enhancing the practical applicability of the prepared TIMs. Overall, this study introduces a novel approach for fabricating flexible composites with high thermal conductivity and low contact thermal resistance, offering new insights into the preparation of TIMs.