Rolled-sonicating enabled orientation of microstructures in flexible nanocomposites

Polymer nanocomposites filled with highly thermally conductive nano/microparticles have shown promise for efficient thermal management in power electronics due to their excellent flexibility and thermal conductivity. However, it remains challenging to align particulate fillers into an optimal heat transfer path through a fast and large-scale green fabrication process, especially when adapting to various types of fillers and flexible matrices. Herein, we report a unique rolled sonication-enabled microstructure orientation (RSMO) method that enables superfast densification and orientation of various fillers in polymers through the synergistic thermo-mechanical effects of high-frequency vibration with roller pressing, achieving full processing within one second without external heating. Ultrasound-induced dense packing and oriented structures synergistically enhance both thermal conductivity (an increase of 171%) and tensile strength (19-fold enhancement) compared with simple roller pressing. RSMO has been demonstrated to be applicable to a wide range of fillers, including metals, inorganic nonmetals, and organic materials, as well as various film-forming techniques, such as electrospinning and screen printing. We successfully fabricated large-area thermally conductive films using RSMO and demonstrated their thermal management capabilities in power electronics and flexible thermoelectric generation, thereby confirming their significant potential in preparing high-performance thermal management materials for flexible electronic devices.