Brick-and-mortar engineered Trimethoxy (2-phenylethyl) silane@h-BN/polyarylate nanofiber paper with ultrahigh thermal conductivity and dielectric strength

The integration of ceramic fillers with high thermal conductivity into polymer fiber insulating paper enhances both thermal conductivity and dielectric strength. Nonetheless, elevated filler loadings augment the filler-matrix interface, thereby intensifying phonon scattering. Additionally, filler agglomeration, driven by van der Waals forces, impedes the formation of a continuous thermal network and introduces defects that facilitate electrical treeing. This research draws inspiration from “brick-and-mortar” architectures, employing high-surface-area thermotropic liquid crystal polyarylate (PAR) nanofibers as the continuous mortar and surface-modified hexagonal boron nitride (TMS@h-BN) nanoplates as the bricks. A scalable papermaking process is employed to fabricate high-thermal-conductivity insulating paper with a high filler content. The three-dimensional network structure of PAR nanofibers spatially confines the h-BN nanoplates, effectively preventing their agglomeration. Furthermore, π-π conjugation between the aromatic structures of PAR and the benzene rings of h-BN enhances interfacial bonding by facilitating the diffusion and entanglement of PAR molecular chains during thermal pressing. This results in a dense interfacial structure that provides an efficient pathway for phonon transport, thereby enhancing thermal conductivity and minimizing electrical distortion. At a filler loading of 70 wt%, the TMS@h-BN/PAR nanocomposite paper exhibits superior mechanical performance and flexibility, achieving an in-plane thermal conductivity of 14.19 W·m −1 ·K −1 and a breakdown field strength of 111.17 kV/mm, which represent significant improvements over commercial insulating paper. Additionally, it demonstrates exceptional thermal stability and flame retardancy, with minimal dimensional changes following heat treatment.