Constructing 0D/2D Boron Nitride Hybrids Enables Thermally Conductive Polyurethane-Based Composite for Flexible Thermal Management

Abstract

The increasing integration and high-power density of flexible electronic devices have driven a growing demand for efficient heat dissipation, promoting the development of high-performance thermal interface materials (TIMs). Herein, boron nitride particles (BNPs) were in situ grown on boron nitride sheets (BNSs) via high-temperature pyrolysis and subsequently incorporated into waterborne polyurethane (WPU) to fabricate WPU/BNS@BNP composites integrating superior thermal conductivity (TC), outstanding dielectric characteristics and excellent mechanical properties. Remarkably, at only 5 wt % filler loading, the WPU/BNS@BNP composite exhibits an impressive through-plane TC of 2.74 W·m–1·K–1, which is 13 times higher than that of pure WPU (0.211 W·m–1·K–1), outperforming WPU/BNS composites containing the same mass fraction of filler. Infrared thermal characterizations and chip heat-dissipation tests jointly validate the superior heat transfer capability of the WPU/BNS@BNP composites. In addition, the WPU/BNS@BNP composite maintains favorable mechanical properties, including a tensile strength of 14.5 MPa, an elongation at break of 207%, and a Young’s modulus of 42.9 MPa. Meanwhile, it exhibits outstanding dielectric characteristics (dielectric loss of 0.0024 and dielectric constant of 3.35 at 1 kHz) and superior electrical insulation (volume resistivity >1016 Ω cm). This work provides a strategy for developing integrated TIMs in advanced smart wearable devices.