Preparation Of Polymer/Inorganic Semiconductor Nanofibers And Study On Their Photics Properties

Since Lijima found the synthesis method of carbon nanotube (CNT) in 1991, the preparation and functionalization study of one-dimensional (1D) or norm one-dimensional nanomaterials have received extensive attention of corporations and scientists. At present, the methods for the synthesis of 1D nanomaterials can be found everywhere, such as gas-solid, liquid-solid, gas-liquid-solid, self-assembly, et al. At the beginning of 21st century, some researchers focus on the synthsis, characterization and applications of electronic polymer materials under the development trend of micromation and nanomation in photoelectric devices. Single and multiple component 1D nanopolymers with different structure and properties were mainly prepared by insular double group composite filature, templet synthesis, electrospinning and polymer limitted region etc. A.G. MacDiarmid, a professor who got the Nobel Prize, reported the fabrication of PAN nanofiber via electrospinning method in 2002. The average diameter of PAN nanofibers was about 139nm. Therefore, the electrospinning technology provided a novel idea for the preparation of polymer and polymer/inorganic composite nanofibers.Compared with conventional solid materials, 1D semiconductor nanostrucure (dot, line, tube, webbing) materials possess special functions owing to the nano-scaled effect, such as laser light action and high photoluminescence characteristic etc. These unique properties originate from that the changing of semiconductor nanostructure energy level or the special geometrical structure produce accessional electron engergy level. It is a challenging task to make full use of the flexibility and tenacity of polymers and the rigidity, heat-resistance, friction-resistance and chemistry stability of inorganic semiconductor materials to manufacture 1D composite nanomaterials with predominant properties. Electrospinning, a simple and convenient technology for preparing 1D nanostructure materials, has received special interest of researchers. The raw materials for electrospinning was solutions or melt from polymers or their mixtrues and the driving force was the high voltage electrostatic force. During electrospinning, the polymer solution or melt was draught and thinned fleetly with the volatilization of solvent or solidification of melt under the electric force and electrostatic repulsive force. Consequently, the nanofiber matters were obtainned ultimately on the take-over electrode. Therefore, in this paper, we screened out precursory poly(phenylene vinylene) (PPV) as the electrospun solution, which bears excellent photoluminescence, electroluminescence, photoelectricity and nonlinear optical properties. Finally, we prepared several kinds of 1D or norm 1D polymer/inorganic semiconductor composite nanofibers via combining electrospinning technology with sol-gel or self-assembly method. The photical properties of as-prepared nanofibers were also studied by the numbers.Detailed content:(1) The precursory PPV solutions in water or ethanol with different concentration were synthesized from alpha, alpha's-dichloro-p-xylene and tetrahydrothiophene. Moreover, in order to establish basic for preparing composite nanofibers, the physical parameters (concentration, conductivity, surface tension, etc.) affecting the morphology of ultrafine fibers were explored. As a result, the relational information about the effect of solutions'physical properties on the surface conformation of nanofibers were opened out.(2) We selected inorganic semicondutor materials (TiO₂, CdS, AgS and CuS, etc.) and polymer furtherance materials (poly(ethylene oxide) (PEO), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), etc) to prepare new-style 1D polymer/inorganic semi- conductor composite nanofiber felts (PPV/PVA/CdS, PPV/TiO₂, PVP/TiO₂, PEO/CdS, etc.) via combining electrospinning technology with sol-gel or self-assembly method.(3) Two dimensional film structures made from 1D polymer/inorganic semiconductor composite nanofibers were characterized by using modern analysis and testing means (SEM, TEM, PL, XPS, etc.). The luminescence, surface photoelectric charge action, luminescence efficiency and the effect of composite structure of nanofibers on the luminescent intensity were investigated. In addition, the tropism mechanism and affecting factors of 1D semiconductor materials, as well as the key factor during the preparation of composite nanofibers, were researched completely. Simultaneously, the basic science problems obout the design and preparation of polymer nanofibers, as well as the luminescence and photoelectricity conversion in practical applications were opened out. These investigations not only enriched the synthesis methods for inorganic nanoparticles, but also provided a novel means and practical gist for designing and synthesizing 1D polymer/inorganic composite nanomaterials. Consequently, practicality course of polymer nanomaterials were quicken.