A controllable salting-out engineering strategy to promote the anisotropic thermal conductivity performances of BNNS@PVA aerogel-based composites by constructing thermal transfer network

Abstract

Thermal interface materials (TIMs) with excellent thermal conductivity are urgently required to tackle serious heat accumulation issues within the miniaturized electronic devices in electronic packaging field. Constructing thermal conductive network can enhance the thermal conductivity of polymer-based TIMs, but significantly restricted by the filler content and the orientation, thereby limiting the directional heat transfer behavior. In this work, BNNS@PVA aerogel with anisotropic thermal conductive network is proposed by sequential synthesizing routines, including the construction of PVA aerogel template by directional freeze-drying, surface assembly of BNNS-OH on the skeleton by dip-coating, and the alignment of the interconnected thermal conductive network by salting-out treatment. The relationship between the thermal conductive network microstructure and the thermal conductivity performance of BNNS@PVA is investigated by physiochemical characterizations and finite element simulation. By optimizing the filler content and the salting-out conditions comprehensively, the resulting aerogel with well-aligned microstructure achieves thermal conductivity of 4.63 W m⁻¹ K⁻¹ and anisotropic thermal coefficient of 473. Besides, the heat dissipation, compressive, and dielectric properties of the aerogels are performed. This research provides a promising strategy to enhance thermal conductivity performance by controlling the anisotropic alignment of the thermal conductive networks effectively, presenting great potential in the advanced polymer-based TIMs.