Cross-linked polymer phosphorescence fibers based on chitosan and corresponding wet-spinning processing

Organic room-temperature phosphorescence (RTP) material is a new kind of triplet emission material, which shows great advantages in applications. How to realize the green preparation and processing of this kind of material attracted increasing attention, while the related works were still rare. In this work, a natural polymer of chitosan was selected as the rigid matrix to construct RTP materials, while aromatic carboxylic derivatives were introduced as phosphor guests, and citric acid was employed as a crosslinking agent to enhance phosphorescence intensity, lifetime and structural stability. Through a simple and environmentally friendly amidation reaction, the crosslinked RTP polymers with blue-green-red emissions were successfully prepared. Further on, a green wet-spinning processing was utilized to optimize the alignment of polymer chains, significantly improving RTP performance with the achievement of the phosphorescence lifetime up to 1.58 s in chitosan-based filaments. In addition, filaments with excitation-dependent RTP property were successfully prepared with a similar method, which exhibited dynamic color changes across the visible region as the excitation wavelength changed. These unique properties highlight their potential for applications requiring dynamic, long-lived luminescence.