Preparation and properties of photochromic regenerated silk fibroin/ Tungsten trioxide nanoparticles hybrid fibers

Natural silkworm silk is traditional high-grade textile material. However, functional types of silkworm silk are scarce, such as photochromic silk. Because Tungsten trioxide nanoparticle (WO3 NPs) is a good typical photochromic material, it may be a potential material to produce photochromic fabrics. In this research,a series of photochromic hybrid fibers composed of regenerated silk fibroin (RSF) and WO3 NPs with different mass ratios have been prepared by wet spinning, which endowed the hybrid fibers with enhanced mechanical properties and excellent photochromic properties. Among the hybrid fibers, 4 wt%-RSF/WO3 NPs hybrid fibers had the highest breaking stress and breaking strain, which reached to 214.52 +/- 16.00 MPa and 97.82 +/- 17.50%. Tensile test of the hybrid fibers showed that the toughness was improved and the breaking energy reached 129.14 +/- 25.56 MJ/ m3. The experimental results indicated the hybrid fibers color changed rapidly change and reached their maximum within 5 s under the ultraviolet light and 1 min under the sunlight. The hybrid fibers still retained good photochromic ability after more than 20 repeated tests. It can be seen from above that the RSF/WO3 NPs photochromic hybrid fibers may have great potential in photochromic fabrics and military camouflage.