Fabrication Of One-Dimensional Micro-Nano Structure Materials Via Electrospinning

One-dimensional (1D) nanostructural materials have been a subject of intensive research due to their unique properties and intriguing applications in many areas. A large number of fabrication methods have already been demonstrated for generating 1D nanostructure materials in the form of fibers, wires, rods, belts and tubes. Among these methods, electrospinning seems to provide the simplest approach to nanofibers with both solid and hollow interiors that are exceptionally long in length, uniform in diameter, and diversified in composition. Comparing with a number of processing techniques of fabricating micro fibers such as melt spinning, wet spinning and dry spinning, and nanofibers such as island spinning, template synthesis, etc., electrospinning offers several obvious advantages: (1) the process of fabricating nanofibers is simple and efficient; (2) the diameters of nanofibers fabricated can be easily controllable; (3) the range of the application is wide. In addition, these nanofibers may provide a connection between the nanoscale world and the macroscale world, since the diameters are in the nanometer range and the lengths are kilometers.In this dissertation, we combined electrospinning process with template and sol-gel technique, trying to fabricate 1D micro-nano structure materials. It involves four parts of works.In the first section, we studied the electrospinning process of Polyacrylamide (PAAm) with ultra high molecular weight and prepared the PAAm micro-nano fibers. Since PAAm had ultra high molecular weight, there were some interesting results in the electrospinning process of it. All kinks of morphologies of the electrospun products such as polymer particles, beaded fibers, smooth fibers and ribbons can be obtained in a small range of solution concentrations. At the same time, caused by the high viscosity we also obtained some special electrospun fibers as helix, zigzag and branched fibers. The detail studies on the mechanism of electrospinning indicated that the solution rheology and the solubility of the polymer in the solvent all had some effects on the morphology of electrospun products.In the second section, we used a kind of polymer, polyvinyl pyrrolidone (PVP), as template to prepared inorganic nanofibers with smaller diameter. By adjusting the parameters of the solution, we can obtain ultra fine Zirconia nanofibers which had an average diameter of 80 nm. Silica nanofibers with mesoporous also can be fabricated by adding structure directing agent P-123 and the calculated results of N2 adsorption-desorption isotherm indicated the average diameter of the pores was 3.46 nm.In the third section, using silica sol as the spinning solution instead of a polymer solution, we fabricated silica nanofibers without any template. This method can be succeed because the silica acted as oligomer of silicate after hydrolysis. The sol was more like a polymer solution.In the last section, developing the method described in the third section, we synthesized Zirconia/Silica (ZrO2/SiO2) complex nanofibers and sulfated Zirconia/Silica (SZ/SiO2) complex nanofibers. Three routes was used to prepare these complex fibers. In the two routes we used co-hydrolysis sol and mixed sol as spinning sol to fabricate ZrO2/SiO2 and SZ/SiO2 complex nanofibers respectively. In the last route, we dipped the as-electrospun silica nanofibers into a SZ sol, after calcination, the SZ/SiO2 complex nanofibers were obtained. SEM,FT-IR,TGA,XRD and SPS were employed to characterize the structure of these fibers. Results indicated that the complex nanofibers have an amorphous structure. Caused by the different the fabricated route, Zr atom and silica had different relationships. The observation of the surface-related transitions at the SPS spectrum indicated the presence of positive charges on the surface of the SZ/SiO2 complex fibers which was fabricated in the third route.