Engineered Cellulose Nanofiber/SiC Nanowire Films via Combustion Synthesis and Alignment for High-Performance Flexible Thermal Management

The pursuit of high-performance, flexible thermal interface materials (TIMs) is hindered by the difficulty in simultaneously achieving efficient filler production, uniform dispersion, and multifunctional synergy in polymer composites. To address this, we presented an integrated engineering strategy that combined rapid combustion synthesis, a tailored dispersion pretreatment, vacuum-assisted alignment, and interfacial hydrogen-bonding design. Specifically, high-aspect-ratio silicon carbide nanowires (SiCNWs) were rapidly synthesized via combustion synthesis. A combined crushing–ball milling–rotary evaporation process effectively improved their dispersibility, after which they were aligned in-plane within a cellulose nanofiber (CNF) matrix through vacuum filtration. Effective interfacial adhesion was achieved via hydrogen bonding between the surface oxide layer of SiCNWs and the CNF. The resulting composite with 40 wt % SiCNWs exhibited an in-plane thermal conductivity of 22.3 W·m^–1·K^–1 (a 20-fold enhancement over pure CNF) and a tensile strength of 93 MPa, while retaining excellent electrical insulation (>10⁹ Ω·cm) and thermal stability. These exceptional properties arose synergistically from the aligned conductive network and the hydrogen-bond-enhanced interface, which facilitated phonon transport and stress transfer concurrently. This work not only demonstrates high-performance flexible TIMs but also provides a facile and practical route for fabricating multifunctional composites for next-generation electronic thermal management.