Study Of Preparation And Properties Of Poly(vinyl Alcohol)/silver Nanowires Composite Fibers

Poly(vinyl alcohol)(PVA) fibers, as one of the synthetic fibers, is widely used in the fields of industry, fisheries and medical treatment. However, fibers with single function can no longer meet the demand for use, and the preparation of multifunctional composite fibers has attracted more and more attention. Among all these, a vast amount of research work have been done on core/sheath composite fibers, because the composite fibers can take special advantages of the core layer and the sheath layer simultaneously.In this work, Ag NWs were added to PVA microfibers, and the PVA/Ag NWs microfibers prepared by wet spinning were directly used as collector for electrospinning PVA nanofibers, to prepare the micro/nano composite fibers with PVA/Ag NWs microfibers as cores and PVA nanofibers as sheaths.The main research content and conclusions are as follows:(1) Silver nanowires(Ag NWs) were prepared by a solvothermal process. The morphology and structure of Ag NWs were characterized by scanning electron microscope(SEM) and X-ray diffraction(XRD) analysis. The results show that the Ag NWs present a linear shape with high purity. The Ag NWs have a large length-diameter ratio, and the diameter of Ag NWs is ranging from 80 nm to100nm.(2) PVA/Ag NWs microfibers were prepared by wet spinning, and the morphology, electrical conductivity and mechanical property were studied. The results show that the surfaces of the PVA/Ag NWs microfibers are smooth, and the addition of Ag NWs has little effect on the surface morphology. The conductivity of the PVA/Ag NWs microfibers appears to be on the rise with low Ag NWs content, and reaches the maximum when the Ag NWs content is 0.75 wt%. However, the conductivity decreases when the Ag NWs content further increases. The conductivity of the PVA/Ag NWs microfibers also decreases with the increasing draw ratio. When the Ag NWs content increases from 0 wt% to 1.25 wt%, the strength of PVA/Ag NWs microfibers decreases from 370 MPa to 177 MPa, and the elongation at break decreases from 11.7% to 1.3%.(3) Micro/nano composite fibers with PVA/Ag NWs microfibers as cores and PVA nanofibers as sheaths were fabricated by electrospinning using the PVA/Ag NWs microfibers as a grounded collector directly. SEM images show that the nanofiber sheaths distribute uniformly around the PVA/Ag NWs microfibers, and the thickness of the sheaths is affected by Ag NWs content and the conductivity. The thickness of the nanofiber sheaths also increases with the electrospinning time, and the rate of increase slows down with the time. The orientation degree of nanofibers increases from 33% to 94% after hot drawing. The antibacterial property and cell adhesion of the micro/nano fibers have been tested. It is found that the composite fibers possess a certain antibacterial activity against E. coli and S. aureus, and show good adhesion property for human osteoblast.(4) 3-Mercaptopropionic acid(MPA) was used to modify the Ag NWs to obtain functionalized Ag NWs(f-Ag NWs), then the morphology and structure of the f-Ag NWs were characterized. The results show that MPA can adhere to the surface of the Ag NWs at low content, and help the Ag NWs to disperse uniformly. While at high content, the degree of agglomeration of Ag NWs increases.(5) PVA/f-Ag NWs microfibers were prepared by wet spinning. The SEM images show that the addition of f-Ag NWs has little effect on the surface morphology of microfibers. The cross sections of the PVA/f-Ag NWs microfibers become rough, which indicates the interaction between the f-Ag NWs and the PVA matrix. The conductivity of the PVA/f-Ag NWs microfibers greatly increases with the introduction of f-Ag NWs. The strength also decreases with f-Ag NWs content similar to with pure Ag NWs, but the effect of f-Ag NWs is less than the Ag NWs.