Co-optimization of thermal and mechanical properties of heated tobacco flakes via a liquid metal nanoparticle-carbon nanotube three-dimensional thermal conduction network

Heat-not-burn (HNB) cigarettes operate at relatively low temperatures (250–350 °C) to heat tobacco flakes (TFs) instead of burning them, thereby reducing the formation of harmful combustion byproducts. However, the inherently low thermal conductivity of conventional TFs results in uneven heat distribution, leading to inconsistent and insufficient release of aerosol constituents. While liquid metal nanoparticles (LM NPs) have been explored as thermally conductive fillers to improve heat transfer, their effectiveness is often limited by discontinuous heat conduction pathways. Herein, we construct a continuous three-dimensional thermal conduction network within TFs by bridging LM NPs with carbon nanotubes (CNTs) in an “island-bridge” configuration. Sodium alginate-encapsulated LM NPs (LM@SA NPs) serve as thermal nodes, while CNTs function as interconnecting bridges. This hybrid filler (LM@SA@CNT) significantly enhances both the thermal and mechanical performance of the resulting TF composites. Compared to pristine TFs, the composite containing 20 wt% LM@SA@CNT exhibits an approximately 50% increase in thermal diffusivity and a 22.5% improvement in tensile strength. These enhancements are attributed to the synergistic effect of the nanoscale “island-bridge” architecture, which facilitates efficient and continuous heat transfer while mechanically reinforcing the TF matrix. This work presents a facile strategy for fabricating high-performance TF composites, offering a material foundation for the next generation of HNB products.