High Thermal Conductivity Hyperbranched Boron Nitride/Nanocellulose Composite Films: Interface Engineering and Performance Regulation
Zhao Yalin1, Liu Boqiang2, Li Songlin2, Ma Guangtong1,2
1. School of Electrical Engineering Southwest Jiaotong University Chengdu 611756 China; 2. State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong University Chengdu 610031 China
Abstract：The relentless miniaturization and power intensification in modern microelectronics, with advanced packaging now reaching power densities of 1 000 W/cm2, have created unprecedented thermal management challenges. Polymer-based thermal interface materials（TIMs), while offering essential electrical insulation and mechanical compliance for electronic applications, are fundamentally limited by their low intrinsic thermal conductivity, typically 0.2~0.4 W/(m·K). This limitation becomes particularly critical in high-power devices, where efficient heat dissipation is paramount to performance, reliability, and operational longevity. This paper develops an innovative bio-based nanocomposite system that combines surface-engineered hexagonal boron nitride（h-BN）with sustainable nanocellulose（CNF）matrices through an optimized vacuum-filtration self-assembly process. The hyperbranched polymer（HBP）functionalization of h-BN surfaces fundamentally transforms the filler-matrix interface, enabling exceptional thermal performance while maintaining the material's structural integrity. Material characterization demonstrates that the three-dimensional HBP architecture successfully bridges h-BN layers and the CNF matrix via its densely functionalized terminal groups. Scanning electron microscopy examinations reveal uniform filler distribution without visible agglomerates across all loading fractions（10%~50%), indicating effective suppression of h-BN's inherent restacking tendency. The vacuum-filtration technique forms well-organized structures in which HBP-modified BN nanosheets form continuous thermal pathways within the CNF network. The structural configuration preserves the biopolymer matrix's advantageous properties while facilitating efficient heat transfer through the composite. Thermal performance evaluation shows remarkable enhancement, with the 50% HBP-BN/CNF composite achieving an in-plane thermal conductivity of 16.941 W/(m·K)-representing a 9.36-fold improvement over pristine CNF（1.809 W/(m·K)）and exceeding most reported bio-based TIMs in literature. This exceptional performance arises from three synergistic mechanisms: first, the aligned BN nanosheet network established via vacuum filtration provides low-resistance pathways for phonon transport. The HBP-mediated interfacial bonding significantly reduces thermal resistance at filler-matrix junctions. The preserved CNF matrix continuity ensures efficient stress transfer. The dynamic mechanical behavior indicates stable performance across the operational temperature range expected for electronic applications. The sustainable composition offers clear environmental benefits over petroleum-derived polymers, while the aqueous processing route is more energy-efficient than traditional hot-pressing methods. Performance metrics position these composites relative to commercial TIMs, particularly for applications requiring both high thermal conductivity and mechanical flexibility. The solution-processable fabrication suggests good potential for scalability. This paper provides fundamental insights into several critical aspects of hybrid nanocomposite development: the role of hyperbranched polymer architecture in modifying ceramic-polymer interfaces, the relationship between nanofiller alignment and anisotropic thermal transport in bio-composites, and the process-structure-property correlations in vacuum-filtered nanocomposites. The HBP-BN/CNF system demonstrates exceptional potential for next-generation thermal management applications that require high performance, environmental sustainability, and processing scalability, particularly in advanced microelectronics, flexible displays, and energy storage systems.
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2026, Vol. 41 
