Strong and multi-responsive composite coiled yarn based on electrospun polyamide-6 nanofiber and carbon nanotube

Polymer based coiled yarns are a new kind of smart materials hold promising applications in various high-tech fields such as artificial muscle, soft robotic, prosthesis, and smart textile. In this paper, we report a facile method for preparation of composite coiled yarn consisted of polyamide-6 (PA6) and single-walled carbon nanotube (SWNT). The homogeneous dispersion of SWNT is first prepared and sprayed on both sides of PA6 nanofiber non-woven, the composite non-woven is then twisted into compact coiled yarn. The uniform coating of PA6 non-woven by SWNT is demonstrated and the incorporation of continuous SWNT network has significantly improved the mechanical properties of composite yarn in comparison with pure PA6 yarn. The good photothermal and electrothermal properties of the SWNT network also endow the composite yarn with near infrared light and electricity responsive ability in terms of contraction that are not possessed in pure PA6 coiled yarn. In addition, the controlled contractive behavior of composite yarn by different voltage is also demonstrated. It is expected that this work could provide an alternative method for strong and multi-responsive composite coiled yarns.