Preparation and fluorescence performance of high elastic core-shell structure composite fibers based on electrospun nanofibers

Fluorescent fibers with light weight and good mechanical properties provide exciting opportunities for the development of flexible optical sensing textiles. This could accelerate the realization of the wearable technology goal of functional and large area display. Here, we synthesized a polyimide containing 20% pyrene group (Py-20) with excellent fluorescence and thermal properties. Then, fluorescent composite fibers with core-shell structure were prepared by using Py-20 electrospun membrane as surface layer and polyurethane (TPU) fiber as inner layer. The diameter and thickness of surface fluorescent fibers was 500 nm and 100 μm, respectively. Polarized infrared spectra analysis proved that the aggregation of polymer molecular chains in electrospun fiber could be reduced effectively. The DR (DR = I∥/I⊥) values of polymer film and electrospun fibers were 0.7553 and 0.5955, respectively. Therefore, the fiber samples exhibited higher fluorescence intensity than the polymer film. The maximum photoluminescence peaks of electrospun and composite fibers were located at about 595 nm. In addition, thanks to interlaced layered structure of electrospun fibers, the fluorescent composite fiber maintained a relatively uniform morphology at 40.84% (strain) and 4.96 MPa (stress). Importantly, this Py-20/TPU composite fiber could meet the complex weaving process of yarns and display bright yellow-orange colors under ultraviolet light irradiation. Thermal analysis exhibited that the initial decomposition temperature (Td) of composite fiber in the air could reach to 269 °C. This fiber material will become a competitive candidate in smart textiles with the excellent luminescence, mechanical and thermal properties.