Wet-spinning fabrication of stretchable multicolor fluorescent fibers augmented with dual-state emissive dyes

Flexible luminous fibers have attracted wide attention in the field of functional and smart textiles. In this work, stretchable multicolor fluorescent fibers were successfully prepared by wet-spinning using thermoplastic polyurethane (TPU) and the boron ketoimine fluorophores (TPA-BKI dyes). Due to the donor (D)-acceptor (A) push-pull electronic system and highly twisted triphenylamine (TPA) skeleton, TPA-BKI dyes exhibited bright emission in both solution and solid states. Meanwhile, the polymer chains further improved the emission efficiency of TPA-BKI dyes in TPU matrix by avoiding close contact between dye molecules, as well as preventing intramolecular rotations in the excited states. Wet-spinning can be used for large-scale and continuous preparation of fluorescent fibers. The TPA-BKI/TPU fibers showed excellent flexibility, high mechanical strength, and bright multicolor fluorescent emission (green, yellow, and red, respectively) when the dye content was as low as 0.1 wt%. Overall, the feasibility of large-scale preparation of fluorescent fibers and their excellent properties, such as flexibility, multicolor fluorescence, and mechanical stability, make them suitable for potential applications, including clothing displays, fashion designs, security, and anti-counterfeiting.