Construction of a 3D aluminum flake framework with a sponge template to prepare thermally conductive polymer composites

Abstract

Ceramic-based polymer composites with high thermal conductivity and electrically insulation have been widely used in modern electrical systems for thermal management applications. Compared with ceramic materials, metals usually exhibit better heat conduction performance. However, the preparation of insulating metal-based polymer composites with high thermal conductivity enhancement efficiency is still challenging. In this study, using PU sponge-supported 3D interconnected aluminum (Al) flakes, a novel advanced polymer composite with high thermal conductivity and desired electrical insulation is reported. The PDMS/PU@Al composites exhibit a thermal conductivity of 1.6 W m⁻¹ K⁻¹ and a thermal conductivity enhancement efficiency of 53 at a low Al flake loading of 14 vol%. Most notably, the thermal conductivity enhancement efficiency is higher than that reported in previous literature. In addition, due to the coating of a nano-SiO₂ surface layer, the PDMS/PU@Al composites are still highly insulating with a volume electrical resistivity of about 10¹⁰ Ω m⁻¹. The Al flake networks exhibit low thermal resistance due to the effective adhesion of the adjacent nanosheets via polyvinyl alcohol (PVA) adhesives and heat flux mainly transferred through the continuous Al flake framework as demonstrated by finite element simulations. These results are very promising in metal-based polymer composites with high thermal conductivity enhancement efficiency. Moreover, the strong thermal management capability of the PDMS/PU@Al composites was demonstrated with an infrared thermal imager, which shows strong potential in thermal management applications.