Modification Of Nano-α-Fe₂O₃ And Nano-SiO₂ To Regenerated Silk

Regenerated silk fibroin（RSF）has good biocompatibility and degradability,and is widely used in the textile field and medical and health fields.In the production and processing process,a certain amount of waste silk will be produced every year,in order to avoid the waste of this excellent protein,the recycling of waste silk is particularly important,silk can be recycled into recycled silk for use.Nano-silica（Silicon dioxide,SiO₂NPs）and nano-iron oxide（Ferric oxide,Fe₂O₃NPs）are nanomaterials with excellent performance,and the use of these nanomaterials to modify silk fibroin fibers can not only reduce the waste of resources but also broaden their application fields.In this study,SiO₂ NPs were introduced into the spinning solution by wet spinning process,and their effects on the mechanical properties,secondary structure and aging resistance of RSF fibers were studied.In addition,polydopamine（PDA）was used as a coupling agent to modify α-Fe₂O₃ NPs on the surface of hybrid fibers to prepare hybrid fibers with anti-ultraviolet function.1.Study on the modification of RSF fiber by SiO₂NPsRSF/SiO₂ NPs hybrid silk was prepared by wet spinning technology,and the effects of SiO₂ NPs add with 0.1 wt%,0.2 wt%,0.4 wt%,0.8 wt%,1.6 wt% and 3.2 wt% mass fractions on the mechanical properties,morphology,thermal stability and aging resistance of RSF fibers were studied.The results showed that the breaking strength（305.67 ± 16.00 MPa）,elongation at break（84.61 ± 17.50%）and fracture energy（225.95 ± 25.56 MJ/m3）of 0.8 wt%-RSF/SiO₂ NPs hybrid silk were significantly improved compared with the blank group RSF fibers.The addition of SiO₂ NPs had no significant effect on the morphology of RSF fibers.When SiO₂ NPs were added at 0.8 wt%,the sample β-fold content at this concentration reached the highest and had better thermal stability.2.Study on anti-aging of RSF/SiO₂ NPs hybrid fibersAccording to the above,the concentration of SiO₂ NPs in the group with optimal mechanical properties was 0.8 wt%,and the changes of mechanical properties and fiber morphology and structure of blank RSF fibers and 0.8 wt%-RSF/SiO₂ NPs hybrid fibers in the outdoor natural light state were investigated respectively during aging at 7 d,14 d,21 d,28 d and 35 d,and the changes of mechanical properties and fiber morphology and structure of RSF fibers and RSF/SiO₂ NPs hybrid fibers in the aging process were analyzed.The results of scanning electron microscopy（SEM）showed that after 35 days of aging,the surface of RSF fiber was significantly wrinkled,and there were no cavities inside.There is no obvious change on the surface of 0.8 wt%-RSF/SiO₂ NPs hybrid fiber,and the internal structure is compact.The mechanical test results showed that the breaking strength,elongation at break and fracture energy of RSF fiber decreased significantly after 35 days of aging,which decreased by52.73%,43.76% and 73.29%,respectively.The breaking strength,elongation at break and fracture energy of RSF/SiO₂ NPs hybrid fibers decreased by 18.21%,37.64% and 51.69%after 35 days of aging,respectively.The results of Fourier transform infrared spectroscopy（FTIR）showed that the β-folded content of RSF fibers decreased by 40.44%,and the β-folded content of RSF/SiO₂ NPs hybrid fibers decreased by 16.49%,indicating that the stability of RSF/SiO₂ NPs hybrid fibers was higher under the same aging time.3.Modification of RSF/SiO₂ NPs hybrid fibers by α-Fe₂O₃NPsα-Fe₂O₃ NPs were used to modify the surface of 0.8 wt%-RSF/SiO₂ NPs hybrid fibers to improve the UV resistance of hybrid fibers.The α optimal concentration of α-Fe₂O₃NPs/PDA finishing solution was determined by ultraviolet absorbance experiment by UV absorbance experiment: 15 g/L concentration of α-Fe₂O₃ NPs and 3 g/L of PDA.The modified hybrid fibers were characterized by scanning electron microscopy（SEM）,energy spectroscopy（EDS）,Fourier transform infrared spectroscopy（FTIR）,and wide-angle X-ray diffraction（WAXD）,which proved that α-Fe₂O₃ NPs were indeed modified on the hybrid fibers by the coupling agent PDA,and the UV absorbance decreases was 21.28% after 20 washes,indicating that the fibers modified by α-Fe₂O₃NPs/PDA finishing solution had good washing resistance.Thermogravimetric testing（TGA）showed that α-Fe₂O₃NPs@RSF/SiO₂ NPs hybrid fibers had better thermal stability than RSF fibers.In addition α-Fe₂O₃NPs/PDA processed hybrid fibers have a good inhibitory effect on Staphylococcus aureus and Escherichia coli.