Fabrication and performance of wool keratin-functionalized graphene oxide composite fibers

The objective of this study is to reduce environmental pollution caused by waste wool and to enable it to be recycled. L-Cysteine was used to dissolve wool in an aqueous solution for the extraction of keratin. Furthermore, the reconstruction of keratin was attempted by dissolving wool keratin in Na2CO3/NaHCO3 buffer with various contents of polyethylene glycol (PEG)- functionalized graphene oxide (PEG-g-GO). Then, the regenerated keratin/PEG-g-GO composite fibers were wet-spun to form a series of composite fibers. Fourier-transform infrared spectroscopy, XPS analysis, Raman spectroscopy, and thermogravimetric analysis were used to characterize the structure and properties of the composite. The results show that PEG was successfully grafted onto the GO. PEG-g-GO had a good interfacial effect with the keratin matrix in composite fibers without any agglomeration, apart from dispersing evenly. With the addition of PEG-g-GO, the crystallinity and the tensile strength and elongation at break of the composite fiber increased, and it induced more beta-sheet secondary conformation within the keratin matrix. When the quality fraction of PEG-g-GO was 0.20%, the tensile strength of the composite fibers reached a maximum (157 +/- 40 MPa) and the breaking elongation reached a maximum of 3.9%, which was approximately 168% and 89% higher than that of the pure keratin fibers, respectively. More importantly, the entire process is green and of low cost, which not only reduces environmental pollution but also improves resource utilization. (C) 2019 Published by Elsevier Ltd.