High-Performance Natural Melanin/Poly (vinyl Alcohol-co-ethylene) Nanofibers/PA6 Fiber for Twisted and Coiled Fiber-Based Actuator

Abstract：Twisted and coiled fiber-based actuators have drawn a greatattention because their unique structure can provide mechanical response withthe external thermal stimulus. Herein, an ultra-fast and light-weight twistedand coiled fiber-based actuator was designed based on a nature melanin/poly(vinyl alcohol-co-ethylene) (PVA-co-PE) nanofibers/PA6 composite fiber. In brief, PA6was firstly coated by melanin/PVA-co-PE nanofibersusing a spraying method, followed by the twisting and coating the compositefiber to obtain the actuator. The excellent photothermal property of melanincontributed to the superior performance of the actuator, whereas the PVA-co-PE nanofibers was responsible for the uniformdistribution of melanin and the enhanced mechanical property of theprepared-actuator. This unique design has led to the high performance of themelanin/NFs/PA6 fiber-based actuator, whose torsion actuation can reach to14,000 rpm, and maximum tensile actuation was − 6.36% at temperaturedifference of 40 ℃. In addition, the tensile stress ofPA6/NFs/melanin fiber was about four times higher than PA6 filaments. Owing tothe simple and environmental-benign preparation method, as well as theexcellent efficiency of twisted and coiled melanin/NFs/PA6 fiber-basedactuator, this study highlights the facile design of the composite fiber forhigh-performance fiber-based actuators. This fiber-based actuator is promisingfor application in energy generator.