High-performance epoxy composites with boron nitride nanosheets: Effect of surface hydroxylation and UPy functionalization on thermal conductivity and flame retardancy

The increasing demand for thermally conductive adhesives (TCAs) in high-performance electronic devices necessitates materials with both flame retardancy and thermal conductivity. Conventional TCAs often struggle with balancing these properties, particularly due to poor interfacial compatibility between fillers and the resin matrix. To address this challenge, this work introduces a novel approach by functionalizing boron nitride nanosheets (BNNSs), with 2,6-bis(urazole-1-yl) pyridine (UPy). This modification enhances both thermal conductivity and flame retardancy in EP-based composites. Thermogravimetric analysis revealed that the initial decomposition temperature ( T 5% ) of the 20-UPy-BNNSs/EP composite increased to 344.8 °C, a 74.0 °C rise from pure EP. Microcalorimetry tests showed a 42.7 % reduction in peak heat release rateand a 17.7 % reduction in total heat release compared to pure EP. Vertical burning tests demonstrated that the 20-UPy-BNNSs/EP composite significantly delayed ignition and suppressed molten droplet formation. In practical electronic device testing, the 20-UPy-BNNSs/EP composite reduced the surface temperature of LED drivers by 53.3 °C compared to the control, highlighting its effective thermal management. These results confirm that UPy modification improves the interfacial interaction between BNNSs and the EP matrix, leading to increased thermal conductivity and flame retardancy. This work proposes a promising strategy for developing high-performance TCAs tailored to next-generation electronics.