Fabrication Of Polymer Micro/Nano Structures Based On Near-field Electrospinning And Applications Research

Compared with the conventional electrospinning, near-field electrospinning can realize accurate control of the deposition of the electrospun fibers, whose diameter can be regulated from tens of nanometers to tens of microns. The electrospun fibers possess lots of advantages such as large specific surface area, special mechanical, electrical and biological characteristics, indicating a great promising prospect for applications in micro/nano technology and biomedical fields.Based on electro-hydraulic dynamics, the electrical and mechanical characteristics of the electrospun jet during spray forming and stable motion region were analyzed, the main reasons why the jet was instable and were analyzed based on Earnshaw's theory and spring damping model, the motion equation was established. The near-field electrospinning experimental platform was constructed, we studied the optimal recipe of electrospinning solution of various polymer materials, fabricated the orderly arranged electrospun fibers and controllable electrospun fibrous patterns, investigated the the process parameters on the influence of morphologies and diameters of the fibers, discussed the main reasons what cause deposition error of near-field electrospun fibers. A "self-aligned" three dimensional near field electrospinning method was proposed and the experimental platform was set up, achieving the consistent and repetitive stacking of electrospun fibers, a variety of controllable and high-aspect-ratio three dimensional microstructures was fabricated, and the accuracy of this three dimensional fabrication method was discussed. At the same time, based on near-field electrospun structures, we investigated the key technology research for applications.The main works of this thesis:(1) The research status of the near-field electrospinning technology at home and abroad was introduced and analyzed, based on the exisiting scientific and technological issues for the near-field electrospinning technique, comfirming the objectives, research contents of this thesis, and the technical route;(2) For near-field electrospinning process, based on electro-hydraulic dynamics, the electrical and mechanical characteristics of the electrospun jet during spray forming and stable motion region were analyzed, such as the critical condition for jet ejection, electric potential and electric field distribution in stable motion region. Based on Earnshaw's theory and spring-damping model, the main reasons why the jet is instable were analyed, and the motion equation was established;(3) Near-field electrospinning experimental platform was constructed, and a series of experiments based on PEO, PVDF and PVP polymer materials were carried out. The optimal recipe of electrospinning solution of those polymer materials was investigated, we fabricated the orderly arranged electrospun fibers and controllable electrospun fibrous patterns, investigated the the process parameters on the influence of morphologies and diameters of the fibers, discussed the main reasons what cause deposition error of the near-field electrospun fibers. A "self-aligned" three dimensional near-field electrospinning method was proposed and the experimental platform was set up, achieving the consistent and repetitive stacking of electrospun fibers. A variety of controllable and high-aspect-ratio three dimensional microstructures were fabricated, The effects of process parameters on the morphologies and sizes of the three dimensional structures were investigated and the accuracy of this three dimensional fabrication method was discussed;(4) Based on near-field electrospinning, the application researches on PVDF single electrospun fiber, electrospun fibers array and the three dimensional grid structure were developed in energy harvesting, transparent electrode and supercapacitor. The prototypes were fabricated and the performance testing and analysis were completed.