Integrating Boron Nitride Nanotubes into Functionalized Boron Nitride/Epoxy Composites Enhances Thermal Conductivity and Other Properties

With the advancement of electronics toward multifunctional, highly integrated, and miniaturized designs, significant heat accumulation has become a critical issue, potentially leading to thermal failure or even explosions. Thus, thermally conductive materials with high dielectric properties have garnered considerable attention in the field of advanced electronics. Polymer-based composites are particularly promising for overcoming this challenge by providing high thermal conductivity with a lower filler content. In this study, we demonstrate a composite consisting of functionalized BN, epoxy, and BNNTs prepared through ultrasonication. This composite exhibits remarkable thermal conductivity, achieving 5.84 W/mK (out-of-plane) and 49.57 W/mK (in-plane) at a 40 wt % filler content. The higher thermal performance of the BNNT(2%) + DNBN/epoxy composite is attributed to several factors: (i) 1D structure of BNNTs creates efficient thermal pathways, facilitating heat transfer within the composite, and (ii) functionalization and strong covalent interactions between DNBN/epoxy and BNNTs reduce thermal resistance and improve heat transfer efficiency, enhancing overall thermal conductivity. The addition of 2% BNNTs to the DNBN/epoxy composite increases the thermal stability, viscosity, and glass transition temperature (Tg). Moreover, the composite demonstrates excellent dielectric properties, with a dielectric constant of 4.2 and negligible dielectric loss (0.0011) at a 40 wt % filler content. The BNNT(2%) + DNBN/epoxy composite, with its superb thermal conductivity and excellent dielectric properties, offers significant advantages for thermal interface materials in advanced electronic applications, ensuring reliability and performance in increasingly demanding environments.