“Branch-leaf” inspired boron nitride/polyimide composites: Covalent grafting for efficient thermal transport at low filler loading

Filler-loaded thermally conductive composites offer a promising solution for thermal management in high-power electronic devices. Nonetheless, conventional physical blending strategies for BN/PI composites face a significant challenge: achieving uniform dispersion and high thermal conductivity simultaneously at low filler loadings is hindered by substantial interfacial thermal resistance. To overcome this challenge, we developed a covalent grafting strategy to construct a unique ‘branch-leaf’ biomimetic architecture through in-situ polymerization. Specifically, amino-functionalized boron nitride nanosheets (BNNS-NH 2 ) were prepared via 2,2′-bis(trifluoromethyl)benzidine-assisted ball milling of hBN. These nanosheets serve as ‘leaves’ grafted onto the polymer ‘branches’ through a dehydration condensation reaction between the amino groups and the carboxyl groups of polyamic acid. Experimental results demonstrate that the in-plane thermal conductivity of the polyimide composite film containing only 10 wt% BNNS-NH 2 is significantly enhanced to 5.43 W/(m·K), representing a 1911% increase compared to the pristine polyimide film. This composite film shows promise as a high-performance thermal interface material (TIM) and lateral heat spreader for high-power integrated circuits. Download: Download high-res image (152KB) Download: Download full-size image