Chitosan grafting coumarin-3-carboxylic acid fluorescent fiber with enhanced strength prepared by in-situ wet-spinning.

Chitosan grafting coumarin-3-carboxylic acid (CS-g-CCA) fiber with fluorescent function and enhanced tensile strength was successfully prepared by in-situ wet-spinning. FTIR and NMR results demonstrate that CCA is successfully grafted onto the CS molecule chains. As the grafting rate increases from 4.2 to 15.8 %, the spinning solution viscosity increases from 22 to 54 Pa·s. SEM observations show that the CS and CS-g-CCA fiber surfaces and cross-sections exhibit homogeneity and smoothness. Likewise, as the drawing ratio increases from 1.0 to 1.4, 2D WAXS patterns illustrate the molecular chain oriented significantly along the drawing direction. The CS-g-CCA fiber (the grafting rate of 15.8 %) exhibits a maximum breaking strength of 1.06 cn/dtex, increasing by 20 % more than the CS fiber. Meanwhile, it has a peak fluorescence intensity of around 480 nm. In addition, the continuous preparation process simplifies the technological route and improves the preparation efficiency of CS-g-CCA fiber. As-prepared CS-g-CCA fiber with enhanced tensile strength and elevated fluorescence efficiency lays the foundation for potential application in fluorescent probes, anti-counterfeiting, and biomedicine fields.