Wet Spinning of Silk Fibroin-Based Core–Sheath Fibers

In order to improve the water absorbency of natural silk and extend its applications in wider areas, silk fibroin (SF)-based fibers were prepared by coaxial wet spinning. Using a custom-made wet spinning device with coaxial spinneret, continuous core-sheath fibers were finally obtained by adjusting the core dope into iota-carrageenan/polyacrylamide hot solution and sheath dope into SF/polyurethane solution. These core-sheath fibers were characterized with respect to morphology, SF secondary structure, mechanical property, and water absorbency. Fibers fabricated from 17 wt % SF/polyurethane solution presented the most regular morphology with homogeneous and circular cross-section. Double-layered hollow structure was observed in these fibers. β-Sheet conformation was mainly adopted by the SF in fibers as indicated in XRD analysis and FTIR spectra. The fibers demonstrated higher absorbency than the raw silk and fine incorporation of long-lasting glowing pigment, indicating potential applications in water or thermal management textile and phototherapy.