Stretchable electrothermochromic fibers based on hierarchical porous structures with electrically conductive dual-pathways

Stretchable color-changing fibers are urgently demanded for smart textiles/clothing due to their perfect implantability, permeability of vapor and heat, and flexibility/ stretchability. Herein, stretchable electrothermochromic fibers were fabricated with unconventional stretchable conductive fibers as core layers and thermochromic coatings as shell layers. In the stretchable conductive fibers, hierarchical porous structures with percolative one-dimensional (1D) conductive networks were constructed through phase inversion of carbon nanotube/polyurethane (CNT/PU) solutions. With the deposition of silver nanoparticles (AgNPs) on the surface of micro-pores, electrically conductive dual-pathways consisting of 0D AgNPs and 1D CNTs were formed to significantly enhance the electric conductivity and thus improve the electrothermal performance of the fibers. More importantly, because of the connective CNTs and AgNPs, such dual-pathways ensured the electron transport under the stretching state, preventing the sharp decay of conductivity and electrothermal performance. Through the continuous wet-spinning method, the stretchable conductive fibers can be easily obtained with the length up to several meters. At last, stretchable electrothermochromic fibers were prepared with two color-changing modes and implanted into textile perfectly, advancing their applications in wearable display and military adaptive camouflage of smart clothing.