Dual experimental-simulation study of ionic liquid-assisted polarized alignment of boron nitride: engineering thermal conductive pathways in polymer composites

Abstract

The increasing power density of modern electronic devices has brought thermal accumulation issues to the forefront, spurring the development of various materials. Among them, thermally conductive polymer composites have shown immense potential. However, achieving high thermal conductivity typically requires a substantial loading of inorganic fillers to form effective thermal conduction networks. To address this, this study explores the use of electric field-assisted alignment facilitated by ionic liquids (IL) to orient boron nitride (BN) and construct efficient thermal conduction pathways at low filler loading. IL/BN/PDMS thermally conductive composite films were prepared, and the mechanism of IL-assisted BN alignment under an electric field was elucidated through a combination of simulations and experiments. Molecular simulations conducted via Materials Studio (MS) reveal that the adsorption of ionic liquid (IL) on the boron nitride (BN) surface is predominantly governed by van der Waals and electrostatic interactions. This interfacial interaction enables IL to act as an orienting agent under an electric field, thereby promoting the directional alignment of BN within the PDMS matrix. The prepared composite films exhibited a thermal conductivity of 0.625 W·m⁻1·K⁻1, a significant improvement over non-aligned films (0.461 W·m⁻1·K⁻1). Additionally, the dielectric constant of the aligned films increased significantly at low frequencies, while dielectric loss rose modestly from ~ 0.5 to ~ 1.5. This study is the first to reveal how IL assists BN alignment. It highlights the advantages of electric field-assisted alignment for preparing thermally conductive composites. The findings offer theoretical insights and practical guidance for developing thermal materials and improving thermal management in advanced electronics.