Flexible and Electrically Insulating MPCF/H-BN/CAB Composites with Engineered Interfaces for Superior Thermal Conductivity

The rapid evolution of flexible wearable electronics necessitates efficient thermal management, driving the demand for materials that are not only thermally conductive but also electrically insulating and flexible. In this study, a thermal conductive composite with aligned filler structure was fabricated using catechol/tetraethylenepentamine (CAT-TEPA) surface-modified hexagonal boron nitride (h-BN) and mesophase pitch-based carbon fibers (MPCF) as fillers, and cellulose acetate butyrate (CAB) as the polymer matrix via evaporation self-assembly and hot-pressing. By optimizing the interface through CAT-TEPA modification and leveraging the long-range structural alignment of MPCF, an efficient thermal conduction network of h-BN sheets was formed. The composite containing 50 wt % total filler content (3 wt % MPCF) achieved an exceptional in-plane thermal conductivity of 21.75 W/mK, and a high volume resistivity of 1.5 × 1011 Ω·cm. Furthermore, the material demonstrated remarkable flexibility, making it a promising candidate for thermal management applications in flexible electronics.