Thermal conductivity of polydisperse hexagonal BN/polyimide composites: Iterative EMT model and machine learning based on first principles investigation

Demand for thermal management materials (TMMs) with efficient in-plane heat dissipation has grown with the advancement of intelligent wireless communication equipment. Herein, polydisperse hexagonal boron nitride (ae-BN) in the range of micrometers to nanometers via aqueous-assisted exfoliation. First principles investigation revealed that ae-BN possess high intrinsic thermal conductivity. A series of ae-BN/PI composites were then fabricated through facile methods: vacuum-filtration and hot-pressing. The ae-BN/PI composites with 30 vol% ae-BN loading exhibited superior in-plane thermal conductivity (6.57 W/(m.K) compared to pristine h-BN/PI composite (3.92 W/(m.K)). SEM images and structural modeling of ae-BN/PI composites revealed that thermal conduction pathways constructed in the composites continuously increased with ae-BN content, attributing to an increased contact probability in composites with higher content of ae-BN. Reduction in thermal boundary resistance of ae-BN/PI composites was proved by our iterative EMT model. In-plane thermal conductivity of aeBN/PI composites with different fillers' contents at variable temperatures were predicted by machine learning technique, viz. artificial neural network (ANN) model. In brief, ae-BN/PI composites with high thermal conductivity, electrical insulation, thermal stability, and mechanical strength were successfully fabricated. The heat conduction mechanism of ae-BN/PI composites was investigated, serving as an important piece of puzzle for the advancement in TMMs of the advanced electronic devices.

Automated summary

With the advancement of intelligent wireless communication equipment, there is an increasing demand for thermal management materials (TMMs) with efficient in-plane heat dissipation. In this study, polydisperse hexagonal boron nitride (ae-BN) particles ranging from micrometers to nanometers were prepared through aqueous-assisted exfoliation. The results showed that ae-BN possesses high intrinsic thermal conductivity. ae-BN/polyimide (PI) composites with different ae-BN loadings were fabricated using vacuum-filtration and hot-pressing methods, and the composites with 30 vol% ae-BN loading exhibited superior in-plane thermal conductivity compared to pristine h-BN/PI composite. SEM images and structural modeling confirmed the construction of thermal conduction pathways in the composites, which increased with ae-BN content. The reduction in thermal boundary resistance of ae-BN/PI composites was demonstrated by an EMT model, and the in-plane thermal conductivity of ae-BN/PI composites with different filler contents at variable temperatures was predicted using an artificial neural network (ANN) model. Overall, ae-BN/PI composites with high thermal conductivity, electrical insulation, thermal stability, and mechanical strength were successfully fabricated, and the heat conduction mechanism was investigated, providing valuable information for the advancement of TMMs in advanced electronic devices.