Researches On Structural Regulation And Controllable Assembly Of Ceramic Electrospinning Nanofibers

Ceramic materials have many properties,including light mass,good thermal conductivity,high temperature stability,excellent mechanical strength and good tolerance from corrision.The electrospinning method can synthesize ceramic nanofibers directly and continuously.On account of ceramic electrospinning nanofibers have a series of technical shortcomings,doping matters into their components and assembling composite materials are effective ways to achieve breakthroughs on their properties.This article focuses on the electrospinning nanofibers,the ordered orientation of PVP on the surface of graphene-doped TiO₂nanofiber membranes and the controllable synthesis of flexible TiO₂and indium tin oxide(ITO)nanofiber membranes.The main contents include the following:(1)The ethanol solution of graphene oxide(GO)was first synthesized by using the Hummer method at first,then the ethanol solution of GO was solved into the electrospinning precursor,synthesizing PVP/GO/Ce(acac)₃nanofibers,PVP/GO/Zr(acac)₃nanofibers and PVP/In-Sn/GO nanofibers afterwards.The incorporation of graphene oxide,electrospinning precursor composition,solvent polarity and PVP concentration can enhance the orientation of GO doped electrospinning nanofibers,and the orientation of the PVP resulting from the GO on the surface of nanofibers.The synthesized PVP/GO/TiO₂nanofibers are calcined in a nitrogen atmosphere to prepare GO/TiO₂ceramic nanofiber.The GO/TiO₂ceramic nanofiber membranes are obtained flower-shaped nanofiber patterns and spiral nanofiber springs by laminated and embossed.In this process,the nanofiber membranes don't crack,break or disintegrate,which show the good flexibility.It proved graphene oxide a good improvement effect to improve the mechanical strength and flexible simultaneously.(2)Attempted to design a series of available methods to explore the available procedure and the technical difficulties on the synthesis of three-dimensional ceramic nanofibers.The liquid-reception method was used to synthesize three-dimensional cellulose acetate nanofibers.By controlling the components of the electrospinning precursor and liquid for the reception phase,as well as a series of variables such as the specific gravity of each component in the liquid phase receiver,the necessary conditions were attempted to find out for the synthesis of three-dimensional nanofibers by the liquid-phase reception method.Afterwards,due to the research on physical chemistry properties of the TiO₂electrospinning precursor,ethyl acetate was selected as the liquid for the liquid-phase reception,and the three-dimensional PVP/TiO₂ceramic nanofiber bulk was successfully synthesized by the liquid-phase reception method.It is proved that the liquid-phase reception method canenable the synthesis of nanofibers with a three-dimensional(3D)structure.The main limitation on the successful preparation of the 3D ceramic nano-fiber bulk was that the high-temperature calcination process is accompanied with the degeneration of the PVP.The nanofibers gradually shrink and collapse,leads to the nanofibers'significantly shrinking in volume,the overall structural strength decreases,and the material tends to be brittle.(3)Through the method of doping nano-ceramic nanofibers into the procedure of self-assemblying,the Al₂O₃aerogel/TiO₂ceramic nanofibers with a three-dimensional structure was successfully obtained.This method takes advantage of the stable physical and chemical properties of ceramic nanofibers,which are stable in complex chemical environments.The nanofibers were solidified together with other materials to obtain a kind of composite material with a three-dimensional structure.This method is easy to operate and could combine the characteristics of ceramic nanofibers with other materials.(4)By studying on the physical and chemical properties of series of indium and tin salts,PVP/In Cl₃/Sn Cl₂nanofibers can be prepared via an electrospinning process from a stable and homogeneous precursor solution.Afterwards,the PVP/In Cl₃/Sn Cl₂nanofibers were sent into a muffle at high temperature for calcination.At different calcination temperatures,amorphous ITO nanofibers and cubic morphology ITO nanocrystals were synthesized.Then the synthesized samples were characterized by SEM and TEM,XRD,TGA,XPS and SAED.The result showed that Sn is successfully incorporated into the lattice structure of the In₂O₃and the prepared material is indeed ITO nano-materials.The crystal size of the ITO nanocrystal is50-60 nm.And the ITO has an amorphous polycrystalline structure after sintered at 400?.the ITO components mainly exist in the form of nanofibers after sintered at 600?,but it is initially doped with square ITO nanoparticles Grain.ITO is completely transformed into cube ITO nanocrystal at 800?.Among the ITO nanomaterials synthesized at different sintering temperatures,the ITO nanocrystal annealed at 800?have the most regular morphology,with the lowest lattice strain value and the highest dislocation density.The ITO nanocrystals synthesized at 800?have the best crystal characteristics and microstructure properties.In addition,the conductivity of ITO nanocrystalline was gradually increased,with the increase of calcination temperature.