Dopamine-Mediated Bacterial Cellulose/Hexagonal Boron Nitride Composite Films with Enhanced Thermal and Mechanical Performance

The high-speed development of miniaturization and densification of electronic devices brings about substantive needs for high thermal conductive and mechanical composites to ensure service reliability and prolong the lifetime of electronic components. Herein, we develop a facile and environmental strategy to fabricate flexible composite films that combine biodegradable bacterial cellulose (BC) and polydopamine (PDA) as well as highly thermally conductive hexagonal boron nitride (h-BN). The well-stacked layered BN0.5@PDA/BC and BN7.0@PDA/BC composite films exhibit higher thermal and mechanical performance relative to the unmodified BN0.5/BC and BN7.0/BC composite films, but the optimum properties closely relate to the size of h-BN fillers. The BN7.0@PDA/BC film exhibits higher in-plane thermal conductivity of 26.8 W·m–1·K–1 than that of BN0.5@PDA/BC films at the same h-BN loading of 82 wt % because the oriented BN7.0@PDA fillers have more probability of forming the effective thermally conductive pathways supported by the Agari model fitting and finite element simulations, whereas the BN0.5@PDA/BC film displays a stronger tensile strength of 18.7 MPa owing to the better match between small-sized BN0.5@PDA fillers and BC nanofibers. Meanwhile, the composite films are employed for cooling high-power LED module application, and the BN7.0@PDA/BC film shows higher cooling efficiency than that of commercial polyimide film. Such a concise and low-cost composite film meets the increasing demands for flexible wearable equipment and foldable electronics.