Hierarchically Structured Bioinspired Fibers Shaped by Liquid Droplets

Abstract Nature has a remarkable ability to create multifunctional fibers, such as spider silk, by precisely controlling structures across various scales. However, replicating this in high‐speed spun synthetic fibers is challenging due to the absence of life‐specific forces and interactions required for manipulating composition, gradients, and structures. Here, a novel droplet‐coupled pultrusion spinning technique is demonstrated for industrial‐scale production of microfibers with hierarchical structures. Droplets spontaneously form on the surface of high‐speed spun fibers to tailor multiscale hierarchical structures, resulting in a nonlinear viscoelastic core embedded with anharmonic nanosprings consisting of amorphous and crystalline domains and a periodically reinforced nanofiber skin. These structural hierarchies enable unique mechanical property combinations including nonlinear viscoelasticity, large extensibility (613%), record‐high toughness (536 MJ m −3 ), highly efficient impact energy absorption, vibration damping and wide temperature adaptability (−67.4 to 278.9 °C). Additionally, the structured bioinspired fibers exhibit low‐frequency phononic bandgap and anomalous dispersion of mechanical waves. The droplet‐based approach allows precise control over heterogeneity at multiple scales within the identical components leading to impressive mechanical performance and additional functionalities, and is consider that it could be applied to the design of the next era of hierarchically structured nanocomposites for a wide range of applications.