Preparation Of Electrospun Nanofibers With Special Arrangement Or Nanostructure

Recently, electrospun nanofiber with special arrangement or nanostructure has attracted much attention. Electrospinning which is the most efficient method for nanofiber has been well developed for single or biaxial arrangement and hollow or core-shell nanostructure. Since the progress of morphology and structure control, the nanofiber could be functionalized for the application of catalysis protector, biomaterials, and filters. In this paper, we investigate the effect of electrospinning setup and electrospun solution on the morphology and structure of nanofiber.First, biaxial orientation electrospun fiber mat was prepared by a novel collector consisting of two rotating disks with conductive edge, which could be considered as a developed form basing on the two classical electrospinning setups. The biaxial orientation structure was formed with the variation of rotation speed without revolving the fiber mat during the electrospinning process, and the dates presented in this paper demonstrated that the degree of biaxial orientation strongly depended on the rotation speed. Second, in the absence of mechanical field, the arrangement of nanofiber is mainly controlled by the distribution of electrostatic field. In order to realize the arrangement of nanofiber in three-dimension, a nongrounded hollow metal box was induced as the collector. Due to the polarization effect, the electrostatic field distribution was consequently changed and enabled the nanofibers standing on the surface of metal box.Third, PHBV (poly(3-hydroxybrtyrate-co-3-hydroxyvalerate)) chloroformic solution was electrospun into nanofibers with "coral-like" surface from a conventional electrospinning setup. The effect of the process parameters, such as spun solution concentration, electrospun temperature, applied voltage, and collect distance, were investigated. The spun solution concentration and temperature played a vital role in the formation of the surface microstructure, and the parameters of applied voltage and collection distance had a weak influence on that microstructure. The formation of the feature surface microstructure was also interpreted by using the polymer phase diagram and Flory interaction parameter (x).Fourth, the nanofibers electrospun from ternary system of PEO (poly(ethylene oxide))/chitosan or its oligosaccharide/water was found with core-shell and internal microphase separation structures. The formation process of these structures was related to the phase behavior during the electrospinning process. The structure could be controlled by changing the component ratio or molecular weight of chitosan and its oligosaccharide. The characterization of TEM, SEM, DSC, and XRD were induced to help to analysis that the real structure in the nanofiber and corresponding component. The core-shell or internal microphase separation structures nanofiber derived from PEO/CS/H2O system would show a potential application for the biomedical fields involving wound care and tissue engineering.