Glucose-Assisted Exfoliation of Hexagonal Boron Nitride Nanosheets and Modification with Hyperbranched Polymers for Thermally Conductive Epoxy Composites: Implications for Thermal Management

As modern electronics evolve toward integration and high power, highly thermally conductive and electrically insulating hexagonal boron nitride (h-BN) has a broader application prospect in the bottom-filling process. However, the low stripping efficiency of h-BN and the poor interfacial compatibility of boron nitride nanosheets (BNNS) in polymers limit the large-scale application of BNNS. To address these issues, a facile glucose-assisted ball milling combined with a cosolvent ultrasonication exfoliation strategy was innovatively introduced into this work to obtain the hydroxylated BNNS (BNNS–OH), which achieves a high yield of 51.56%. On the other hand, the end carboxylated hyperbranched polymer (CHBP) was successfully grafted onto the BNNS via an amidation reaction to enhance their dispersion and compatibility in epoxy resin (EP). The well-established thermal conductivity network and low interfacial heat resistance endow the BNNS-CHBP/EP composites with high thermal conductivity. Typically, the thermal conductivity of the EP composites containing 20 wt % of BNNS-CHBP reached 0.88 W m–1 K–1, which reached an enhancement of 311.7% more than pure epoxy. Moreover, the BNNS-CHBP/EP composites exhibited excellent heat stability and low dielectric loss. This work proposed a simple and feasible strategy to achieve the high-efficient exfoliation and modification of h-BN, which offers a potential possibility to realize the application of BN in electronic packaging underfill materials.