Preparation Of PPV And PPV/PVA Electrospun Fibers And Investigation Of Their Properties

Because of the very small diameters, the high specific surface area per unit mass andthe large surface-to-volume ratio, nanofibers have manifested many chemical andphysical(heat, light-emitting, electromagnetism etc.) special performances, and these fibersare of considerable interests for various kinds of application such as adsorption, filtration,protection and biological medicine. The technologies for the preparation of Polymernanofibers include electrospinning, sea-island model spinning, molecular spinneret spinning,biologic synthesis, chemical synthesis etc. Electrospinng is a effective method of highefficiency and small waste of preparing polymer nanofibers. Electrospinning is the focusway recently and has demonstrated a large potential.Electrospinning origins from that electrically charged fluid is forced jets in the highvoltage electrostatic field. Electrospinning occurs when the electrical forces at the surface ofa polymer solution or melt overcome the surface tension and cause an electrically chargedjet to ejected. When the jet dries or solidified, an electrically charged fiber remains. Thischarged fiber can be directed or accelerated by electrical forces and then collected in mats orother useful geometrical forms. The diameters of electrospun fibers are in the range of tensof nanometers to several micrometers.In this paper, PPV nanofibers and PPV/PVA composite nanofibers are made byelectrospinning the PPV precursor of H₂O/ethanol solution respectly with adjusting the mainprocess parameters including electronoc voltage(7-20KV), sprinkler aperture(0.37-0.84mm),collection distance(10-30cm), solution concentration(the precursor of PPV: 0.1-0.6Wt%;theprecursor of PPV: 0.6-6.7%). The diameters of PPV nanofibers are 200¹000nm;thediameters of PPV/PVA composite nanofibers are 150⁶00nm. The concentration of PPV hasan effect on the diameters of PPV/PVA composites. The processing parameters wereinvestigated detailedly, which were important to the diameters and forms of nanofibers. Andthe results demenstrate the electroststic voltage and solution concentration are determinantto the forms of nanofibers, and restrict the adjustment of other process parameters. On theother hand, the concentration of ethanol is important to the forms of nanofibers. There willbe no bead in the fibers when the concentration of ethanol become higher.Comparing the two kinds of fibers, above PPV fibers with large diameter aren't welldispersed, but fibers of PPV/PVA are well dispersed and small in diameter. Characterizationby PL(photoluminecen) indicates that the PPV fibers remain original light-emittins property.But, we could not notice significant blue shift when concentration become higher, inopposite side, it towards blue shifts. The results of PL are correspond to the results oflight-emittins color of fibers.