The Fabrication Of PS Functional Materials By Electrospinning Method

Research on nanomaterials, which has made huge influence on areas of electronics, information technology, medicine, environmental protection, is a hot issue in today's new materials field. As a newly developed technique, electrospinning method can be used to prepared nano-sized fibers and microspheres (the minimal diameter of fiber is lnm), contributing to great attention from researchers. Many polymer solution and melt can be applied to electrospinning. Due to unique features of electrospinning technology, it can be employed in filters, biomedical materials, thin film manufacturing and so on. In this dissertation, polystyrene is used as raw materials in electrospinning process to prepare PS microspheres, inorganic/organic composite materials and super-hydrophobic surfaceIn the second chapter of this dissertation, electrospinning technique is employed to fabricate PS microspheres, we analyzed the effect of solution concentration, polymer molecular weight to the morphology of the products. The structures and morphologies of products can be effectively controlled by a number of parameters involving concentration of solutions, electrospinning voltage, electrospinning distance and so on. In our experiment, we found that as the polymer solution concentration increases, solution viscosity become large, which leads to the morphology of electrospun products changing from spherical geometry to bead-on-string structure, spindle fibers until the presence of uniform fibers. At the same time, using polystyrene with different molecular, the morphology of product also shows significant differences, though the electrospun solutions are prepared with the same concentration. Higher molecular weight polystyrene is more likely to result in final product comprised of fibers. This is because that the large molecular weight polymer electrospinning solution can significantly increase its viscosity.The focus of the third chapter has been on fabrication of inorganic/organic microspheres with fluorescent properties. Fluorescent microspheres are well concerned as an important kind of functional microspheres. Because of their stable structure and high luminous efficiency, florescent microspheres have been applied in many fields. Electrospinning technology is employed to embed CdSe QDs in polystyrene matrix. We successfully prepared single-colored and double-colored fluorescent composite microspheres. Due to the advantages of large specific surface area of the nanofibers/nanospheres and fast evaporation of the solvents in the electrospinning process, we effectively avoid the occurrence of CdSe QDs aggregation and obtain CdSe/PS electrospun microspheres with stable fluorescent properties, no Forster Resonance Energy Transfer occurs in our experiment. By analyzing the morphology of prepared microspheres, the addition of CdSe QDs leads to microspheres with reduced diameter and uneven surface, which is because that CdSe QDs has effectively enhanced the conductivity of electrospinning solution.The fourth chapter describes the preparation of superhydrophobic surfaces by electrospinning method. Polystyrene is a kind of hydrophobic polymer itself. By selecting polystyrene with different molecular weight to prepare microspheres, we discover that rough microspheres with porous surface reveal superhydrophobic property with contact angle as high as 157.78°. However, the drawback of this structure microsphere is that during CA measurement, some microspheres separated form the substrate and floated on the water droplets because of the low density of porous microspheres and their single dispersion. On this basis, we designed and synthesized bead-on-string fibers to finally obtain superhydrophobic surfaces. Not only do we achieve a high contact angle, but also we effectively avoid the floating of surface materials in water droplets due to the binding effect of long fibers. A new device-multinozzle electrospinning set is designed to place two nozzles at opposite sides of rolling cylinder. One jet is charged with producing bead-on-string fibers which play a key role in enhancing the superhydrophobicity of electrospun mat owing to the rich beads contained. The other nozzle is responsible to introduce micrometer diameter fibers to improve mechanical property of mats, making them more promising in applications. We mainly discuss the effect of weight ratio of bead-on-string fibers and microfibers to the superhydrophobic behavior and mechinal property of electrospun mat.