Enhancement of thermal and dielectric properties in polyimide‐polydimethylsiloxane composites using silane‐grafted aluminum nitride and potassium sodium niobate fillers

Abstract The development of composites with improved thermal conductivity and dielectric properties is crucial for meeting the demands of cutting‐edge technologies, such as power electronics, energy storage systems, and high‐frequency communication devices. These improvements are vital for ensuring efficient energy management and reliable performance in these applications. In this study, potassium sodium niobate (KNN) and aluminum nitride (AlN) fillers are incorporated into a polyimide‐polydimethylsiloxane (PI‐PDMS) matrix to create composites with optimized thermal and dielectric properties. The successful synthesis of KNN is confirmed through x‐ray diffraction (XRD) and field‐emission scanning electron microscopy (FE‐SEM), which show distinct diffraction peaks and a cubic morphology. The surface treatment of AlN with silane coupling agents, such as GPTMS, was analyzed using Fourier transform infrared (FT‐IR) spectroscopy and x‐ray photoelectron spectroscopy (XPS). These techniques confirm the successful fabrication and enhanced surface adhesion between the filler and the matrix. Thermal conductivity measurements show that the addition of AlN, combined with surface modification, significantly improves thermal performance. The PI‐PDMS/AlN composite exhibits a thermal conductivity of 3.34 W/m K. The incorporation of KNN fillers increases the dielectric constant to as high as 300; however, this improvement is accompanied by a reduction in thermal conductivity. The optimized PI‐PDMS/(90AlN‐GPTMS/10KNN) composite strikes a balance between high thermal conductivity (2.7 W/m·K) and excellent dielectric properties (dielectric constant of 30.1 at 10 KHz), which makes it suitable for electronics and thermal management applications. This study highlights the importance of filler surface treatment and composition optimization in the development of high‐performance composites. Highlights Silane‐treated AlN fillers enhance the thermal conductivity of PI‐PDMS composites. Incorporating KNN increases the dielectric constant of the hybrid composites. GPTMS improves filler‐matrix surface adhesion, reducing voids in composites. PI‐PDMS/(90AlN‐GPTMS/10KNN) offers balanced thermal/dielectric properties.