"Snakeskin" Bioinspired Design for Polymer Composite with Enhanced Positive Temperature-Dependent Thermal Conductivity

Albeit there is widespread application of thermally conductive polymer composites, one challenge is their typical negative temperature dependence on thermal conductivity (TDTC) due to the mismatch in thermal expansion between the polymer and fillers, creating voids at the interfaces. Inspired by the hierarchical structure of snakeskin, where rigid scales and a soft intergap manage expansion, we designed a segregated structure by coating a high-expansion high impact polystyrene (HIPS)/graphite (Gt) composite with a copper alloy. We hypothesize that the Cu alloy restricts the thermal expansion of HIPS/Gt while forming a pseudoconductive network, enhancing TDTC and thermal conductivity (TC). The results demonstrate that, compared to a composite prepared via conventional melt mixing, the bioinspired structure increases TDTC between -20 and 80 °C by 290% and TC at 80 °C by 46.5%, respectively. As a bioinspired strategy, our work is the first report on a straightforward, scalable, yet effective approach to design and enhance thermal management of materials.