Air-Jet Wet-Spinning of Curdlan Using Ionic Liquid

Owing to the environmental impact of the textile industry, which distributes petroleum-based synthetic fibers on a large scale, there is a growing demand for renewable biomass-based biodegradable fiber. Curdlan, a linear β-1,3-glucan, can be potentially converted into a functional fiber with excellent sustainability and biodegradability because of its helical crystalline structure and unique physicochemical properties. Herein, we demonstrate a facile and green preparation of regenerated curdlan fibers and characterize the fiber properties via mechanical and structural analyses. Curdlan (9 wt %) in an ionic liquid (1-ethyl-3-methylimidazolium acetate, [Emim][OAc]), was sequentially extruded under a mild condition at 80 °C, drawn in an air gap, and coagulated in water. The resulting fiber was transparent, soft, and had high water-absorption ability (∼86%). By changing the draw ratio from 1 to 10, the molecular orientation of the regenerated fibers increased, resulting in enhanced tenacity (5.2 ± 0.1 cN tex–1 or 75 ± 1 MPa) and Young’s moduli (2.7 ± 0.1 GPa). Although the mechanical strength of these curdlan-regenerated fibers is not comparable to those of conventional cellulose-regenerated fibers, their exceptionally excellent elongation (20–50%) in the dry state is noteworthy, indicating their potential use in different applications from those desired for the cellulose fibers.