Nanowire and Nanotube Materials Prepared from Polymer Fiber Templates
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H7.22.1
Nanowire and Nanotube Materials Prepared from Polymer Fiber Templates By Hong Dong, Verrad Nyame, Wayne E. Jones, Jr.* Department of Chemistry State University of New York at Binghamton Binghamton, NY 13902 ABSTRACT The preparation of well-defined nanomaterials using template methods is well established in the materials literature including porous ceramics, open-framework layered structures and porous membranes. In an effort to prepare thermally and electrically conductive nanowire and nanotube materials, we have recently prepared carbon tubes using polymer fibers produced from an electrostatic, non-mechanical “electrospinning” process as templates. Poly(methyl methacrylate) (PMMA) fibers with average diameter of 150-200 nm were initially fabricated as core materials. The fibers were subsequently coated with a thin layer (20~50 nm) of conductive polypyrrole (PPy) by in-situ polymerization. Upon high temperature (1000 °C) treatment under inert atmosphere, the PMMA core fibers decomposed completely, followed by carbonization of the PPy wall. The structure of the carbon tubes subsequently produced was demonstrated by SEM and TEM. The carbon tubes were analyzed by infrared, elemental analysis and electron diffraction. The results show that the tubes are largely carbon with a small amount of nitrogen and a relatively low crystallinity. INTRODUCTION Nanowire and nanotube materials are predicted to possess unique physical, chemical and electronic properties, which have made them attractive for a variety of applications. For example, nanometer-sized probes [1], electron field emitters [2] and battery applications have been proposed. Various methods for the preparation of nanowires and nanotubes have been reported, including self-assembly and template techniques. Among the template approaches, nanoporous membranes have been frequently used for the synthesis of fibrils and tubules composed of metals [3], conducting polymers [4], semiconductors [5], carbon and graphite [6,7], and composite materials [8]. Recently, we have been exploring a new approach using polymer fibers as templates to synthesize nanowire and nanotube materials. This method entails the fabrication of polymer fibers using a simple, electrostatic method known as “electrospinning” [9-11]. The long fibers produced have diameters ranging from several microns down to tens of nanometers [9], and the diameter is controllable by adjusting the physicochemical parameters of the initial polymer solution [12]. The deposition of different wall materials on the surface of the ultrafine fibers can be achieved by various techniques including chemical vapor deposition [13], sol-gel [14], in-situ polymerization and electroless plating. Using electrospun polymer fibers as templates, tubules of poly(p-xylylene)[13] and titanium dioxide [14] have been prepared by Greiner et al. In our group, we have successfully synthesized fibers and tubes of conductive polyaniline and metal (e.g. Au, Ni).
H7.22.2
Here we report a study of conductive nanowires and carbon tubes prepar
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