Protein-connected three-dimensional boron nitride networks for multifunctional thermally conductive epoxy composites with enhanced structural stability and flame retardancy

초록

Continuous three-dimensional (3D) ceramic networks enhance thermal transport and flame retardancy in polymer composites by providing efficient heat transfer pathways and suppressing combustion propagation, but their fabrication often requires templates, foaming agents, or synthetic binders, increasing process complexity. In this study, a bio-derived protein-foaming-assisted assembly strategy is developed to construct a robust 3D boron nitride (BN) network in epoxy composites. The 3D framework consisted of an albumen‑assisted BN (A-BN) skeleton, in which BN formed the ceramic reinforcement and albumen served as both the foaming agent and binder, creating 3D skeleton. The epoxy composite prepared with 50 vol% BN relative to albumen (A-BN50/epoxy) composite achieved a thermal conductivity of 2.25 W·m−1·K−1 at a BN content of 10.42 vol%, which is 2.89 times higher than that of the randomly dispersed BN (R-BN)/epoxy composite with the same BN loading. The preserved 3D BN network served as a physical barrier during combustion, reducing the peak heat release rate and total heat release by 49.93% and 35.91%, respectively, compared with the R-BN/epoxy composite, while maintaining electrically insulating behavior (>1012 Ω·m). These results demonstrate that albumen-assisted protein foaming enables the multifunctional assembly of thermally conductive and flame-retardant ceramic/polymer composites. Copyright © 2026. Published by Elsevier Ltd.

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