Highly-Dispersed Carboxymethyl Cellulose and Polyvinylpyrrolidone Functionalized Boron Nitride for Enhanced Thermal Conductivity and Hydrophilicity

Hexagonal boron nitride (h-BN) has been widely investigated in the field of thermal interface materials (TIMs) due to its unique physicochemical properties, including high thermal conductivity and electrical insulation. However, poor dispersion of BN in polymers makes it difficult to form promising thermal conductive pathways, resulting in low thermal conductivity when blended with polymers. Therefore, surface modification of BN is usually required to increase its dispersibility and interfacial affinity in polymers. In our work, BN was first hydrothermally treated in alkaline solution to obtain hydroxylated BN, followed by the modification with carboxymethyl cellulose (CMC) and polyvinylpyrrolidone (PVP) by ball milling to further improve the water dispersibility and stability of BN. The prepared hydrophilic BN-OH-CMC-PVP (BOCP) was stably dispersed in water for one month at a concentration of 20 mg mL-1. In addition, the multiple surface modifications effectively improved the dispersion and compatibility of BN in the epoxy, leading to a significant improvement of the thermal conductivity of BOCP/Epoxy composite. The thermal conductivity of BOCP/Epoxy reached 1.64 W m-1 K-1 at 30 wt% loading. The preparation of functionalized BN presents a facile and effective strategy to construct BN-based TIMs with improved dispersion and enhanced thermal conductivity.