Electrospinning Construction And Luminescence-Electricity-Magnetism Functionalization Of Flexible One-dimensional Micro/nanostructures

With the development of nanoscience and nanotechnology,higher requirements have been put forward for materials.Fluorescent-conductive-magnetic（denoted as FCM）multifunctional materials have become one of the research hotspots in the fields of chemistry and materials science because of their superior properties compared with their mono-functional materials and their important application prospects in biomedicine and flexible electronic devices.For the FCM multifunctional materials,when the luminescent material,conductive material and magnetic material are directly mixed together,the luminescent property of the materials will be seriously affected.In order to reduce the adverse influence of conductive and magnetic materials on the luminescent properties,special structure is required to effectively isolate the conductive and magnetic materials from the luminescent material,so as to obtain the excellent FCM multifunctionality of materials.In this dissertation,one-dimensional（1D）Janus nanobelt and Janus microfiber,utilized as the building units,are designed and fabricated by electrospinning technology utilizing the peculiarly designed and assembled spinning spinnerets as well as constructed corresponding spinning devices.Further,Janus nanobelts array film and Janus microfibers array with FCM multifunctionality are constructed by using special collecting devices.Subsequently,these Janus-structured arrays are extended to construct two-dimensional（2D）left-to-right structured,up-to-down structured and step-like structured Janus array films which possess the FCM multifunctionality.The mechanism of FCM mutual interaction and the formation mechanism of these new materials are clarified,and new construction technologies are established.Compared with the contrast samples,these peculiarly structured Janus array films have better conductive anisotropy,magnetism,up-conversion luminescence（UCL）and down-conversion luminescence（DCL）.The novel three-dimensional（3D）Janus nanotubes are obtained by curling the left-to-right structured and the up-to-down structured Janus nanobelts arrays films with different strategies.In addition,FCM trifunctional materials with the same composition,diverse structures and morphologies are constructed by four electrospinning technologies by using the same spinning solutions.The advantages and disadvantages of four electrospinning technologies and the differences in structures and properties of the electrospun products are detailedly investigated.1.Janus nanobelts,fabricated by parallel electrospinning using self-designed and fabricated parallel spinneret and the constructed parallel spinning device,are utilized as conductive and building units to further construct three kinds of multifunctional anisotropic conductive films,including [Fe₃O₄/polyaniline（PANI）/polymethylmethacrylate（PMMA）]//[Y₂O₃:Yb³⁺,Er³⁺/PMMA] Janus nanobelts array film with enhanced UCL,single anisotropic conduction and magnetism;left-to-right structured {[Eu（BA）₃phen/PMMA]//[PANI/PMMA]}⊥{[Y₂O₃:Yb³⁺,Er³⁺/PMMA]//[PANI/PMMA]} Janus nanobelts array pellicles（marked as JAP）;up-to-down structured {[Tb（TTA）₃（TPPO）₂/PMMA]//[PANI/PMMA]}&{[Y₂O₃:Yb³⁺,Er³⁺/PMMA]//[Fe₃O₄/PANI/PMMA]} bilayer Janus nanobelts array membranes（noted as BJNAM）.Both the left-to-right structured JAP and up-to-down structured BJNAM possess double anisotropic conduction,UCL and DCL owing to their peculiar structure,besides,BJNAM also have adjustable magnetic property.When PANI content is 70 %,the anisotropic conductance ratios of left side and right side pellicles in JAP can both reach 10⁸ times.3D Janus nanotubes with novel structure and morphology are obtained by curling the left-to-right structured and the up-to-down structured Janus nanobelts array films with various strategies,which possess unique FCM multifunctionality.These new materials have potentials in electronic devices,electromagnetic shielding and biomedicine.2.Janus microfiber is designed and fabricated by conjugate electrospinning using the constructed conjugative electrospinning apparatus.Janus microfibers are used as building units to further construct [Fe₃O₄/PANI/PMMA]//[Eu（TTA）₃（TPPO）₂/PMMA] Janus microfibers arrays with FCM trifunctionality of adjustable electrically anisotropic conduction,magnetism and enhanced DCL.The formation mechanism of Janus microfibers and their array are elucidated and a brand-new technique for constructing 1D Janus microfibers and their array is established.The adjustability of conductive anisotropy and magnetism of Janus microfibers array is realized by respectively modulating the contents of PANI and Fe₃O₄ NPs.In order to verify the universal versatility of the established conjugate electrospinning,magnetic-fluorescent bifunctional [Fe₃O₄/PMMA]//[Tb（TTA）₃（TPPO）₂/PMMA] Janus microfibers array,conductive-fluorescent bifunctional [PANI/PMMA]//[Tb（BA）₃phen/PMMA] Janus microfibers array and conductive-magnetic bifunctional [PANI/PMMA]//[Fe₃O₄/PMMA] Janus microfibers array are also prepared.The partition of the two functional areas is achieved by using Janus microfiber,which can effectively separate fluorescent materials from magnetic nanoparticles and conductive materials to obtain excellent multifunctionality.The products are endowed with FCM bi-or tri-function,creating the high integration of these functions with Janus microfibers array.3.Anovel 2D dual-layer step-like Janus array film（abbreviated as DSJAF）,based on one-dimensional Janus nanobelt and Janus microfiber as the building units,is devised and fabricated by efficiently combining conjugate with parallel electrospinning technology as a new technology.In DSJAF,the up-layer Janus nanobelt array film covers the left half of the bottom-layer Janus microfiber array film and the two films bind together to form the step-like composite film,achieving two sets of Janus structures respectively from top to down on the left half of DSJAF and from left to right on the top surface of DSJAF as well as resulting in multiple anisotropic conduction of DSJAF.The conductance ratios between conductive and isolative direction in the up-and bottom-layer film of DSJAF can respectively reach up to ca.10⁸ and 10⁷ when PANI percentage is 70 %,indicating that conductive anisotropic degree of DSJAF is modulated by diverse building units of Janus microfiber and Janus nanobelt.In addition,DCL,UCL and adjustable magnetism are concurrently acquired in DSJAF,and the mechanism of FCM interaction is clarified.The exceptive structure of 2D DSJAF achieves the macroscopic partition and Janus nanobelt and Janus microfiber used as building units realize micro-partition,and the efficient integration of micro-partition with macro-partition is actualized in the 2D DSJAF to avoid or reduce the adversely reciprocal interferences among different functional substances and obtain excellent multifunctionalities.The new-typed 2D step-like DSJAF can be extended to assemble other materials with diverse functions to acquire excellent polyfunction.4.Different electrospun products with diverse structures are respectively fabricated by conjugate electrospinning,parallel electrospinning,coaxial electrospinning and traditional electrospinning technologies using same spinning dopes.The advantages and disadvantages of the four electrospinning technologies,the differences in the structures,morphologies and FCM trifunctionality of the electrospun products are further systematically investigated,which have important guiding significance to fabricate multifunctional nanomaterials via selecting a specific electrospinning technology.