Conjugate Electrospinning Construction And Characteristics Of Flexible One-Dimensional Nanostructures Endowed With Upconversion Luminescence-Electricity-Magnetism Multifunctionality

With the rapid development of nanoscience and nanotechnology,nanomaterials with single function can not meet the demands of people.Therefore,multi-functional nanomaterials have gradually become one of hotspots in the fields of materials science,chemistry and condensed matter physics.As one of the one-dimensional（1D）nanomaterials,nanofiber yarn has unique advantages of large aspect ratio,high porosity,strong mechanical properties,etc.It is often applied for construction of multi-functional materials,and has important application value in the fields of novel energy,biomimetic science,photoelectric devices,etc.It is often applied in the construction of multi-functional materials.Electrospinning technique is one of the facile and efficient techniques for preparing nanofiber yarns.Therefore,it is of great significance to utilize electrospinning technology to endue nanofiber yarns with luminescent-magnetic-conductive versatility and to study their performances.In this thesis,multifunctional nanofiber yarns with upconversion luminescence,conductivity and magnetism were constructed by applying modified conjugative electrospinning technology.The performances of prepared nanofiber yarns were systematically characterized by modern characterization and test methods,and the details are as follows:1.[Y₂O₃:Yb³⁺,Er³⁺/polyacrylonitrile（PAN）]//[CoFe₂O₄/PAN] upconversion luminescent-magnetic di-functional alloplastic nanofiber yarns（ANYs）were obtained by conjugative electrospinning technique.The nanofiber yarns are composed of luminescent nanofibers and magnetic nanofibers,which forms two different functional partitions and avoids the adverse effect of magnetic materials on luminescent properties.ANYs exhibits 9 times higher upconversion luminescent intensity than that of coessential nanofiber yarns（CNYs）as contrast sample.The mechanical and magnetic properties can be respectively modified by adjusting the twist and the content of CoFe₂O₄ nanoparticles（NPs）.2.[Y₂O₃:Yb³⁺,Er³⁺/PAN]//[CoFe₂O₄/polyaniline（PANI）/PAN] upconversion luminescent-magnetic-conductive tri-functional ANYs were constructed by conjugative electrospinning.The luminescent substances,conductive substances and magnetic substances are evenly distributed in the luminescent nanofibers and electromagnetic nanofibers respectively without direct contact,which greatly avoids the adverse effects of dark colored magnetic and conductive materials on the luminescent properties.The conductivity of ANYs can be controlled by changing the content of PANI.When the mass percentage of PANI is 50%,the conductivity reaches 1.75×10-3 S·cm-1.3.[NaYF₄:Yb³⁺,Er³⁺/Eu（TTA）3（TPPO）2/PAN]//[CoFe₂O₄/PANI/PAN] up/downconversion luminescent-conductive-magnetic multifunctional ANYs were prepared by utilizing conjugative electrospinning technique.The up-conversion luminescent NaYF₄:Yb³⁺,Er³⁺ NPs and down-conversion rare earth complexes are introduced into the luminescent nanofibers to realize the up-/down-conversion dual-mode luminescent performances.Two independent micro partitions formed by luminescent nanofiber and conductive-magnetic nanofiber realize the complete separation of luminescent substances from magnetic substances and conductive substances,and the luminescent properties of ANYs is greatly enhanced.Moreover,the luminescent intensity,magnetic and conductive properties can be respectively tuned by changing the contents of luminescent,magnetic and conductive substances.