Nanofibers preparation template method

A variety of nanomaterials have been synthesized by many researchers using anodic aluminum oxide film as either a template or a host material e.g., magnetic recording media (13,14), optical devices (15-18), metal nanohole arrays (19), and nanotubes or nanofibers of polymer, metal and metal oxide (20-24). No one, however, had tried to use anodic aluminum oxide film to produce carbon nanotubes before Kyotani et al. (9,12), Parthasarathy et al. (10) and Che et al. (25) prepared carbon tubes by either the pyrolytic carbon deposition on the film or the carbonization of organic polymer in the pore of the film. The following section describes the details of the template method for carbon nanotube production. 

In the template synthesis method, nanofibers are produced in hollow channels of porous ceramic or polymer templates. Figure 13.12 shows the nanofiber formation process using the template synthesis method. The porous template first is filled with monomers. Polymer nanofibers are synthesized from the monomers chemically or electrochemically in the hollow chaimels of the porous template. Separated nanofibers are obtained after the removal of the template by dissolving or etching. Figure 13.13 shows a SEM image of polypynole (PPy) nanofibers prepared by the template synthesis method. Nanofibers produced by template synthesis often have a hollow stmcture because the synthesized polymer tends to precipitate onto the inner surface of the hollow channels. 

According to this formula, for a given oxidant the resultant nanofiber diameter can be predicted. The dopant-free template-free method not only provides a quantitative way of controlling the diameter of the PANI-NFs, but also simplifies the reagents. PANI-NFs were successfully prepared by using the dopant-free template-free method through the... 

Four-probe pressed-pellet conductivities for PANI emeraldine hydrochloride nanofibers are in the range 2-10 S cm [51], similar to conventional PANI emeraldine hydrochloride powder [1]. Maximum conductivities of PANI-NFs prepared by various template and template-free methods are given in Tables 2.1 and 2.2, respectively. 

There are various methods to synthesize polymer nanostructures, i.e., template synthesis, chiral reactions, self-assembly, interfacial polymerization and electrospinning. Recent developments in conducting polymer nanotubes and nanofibers were summarized by Long et al. Different preparation methods, physical properties, and potential applications of one-dimensional nanostructures of conjugated polyaniline (PANI), pol5 3nrole (PPy) and poly (3, 4-ethylenediox3d hiophene) (PEDOT) were discussed. 

Several synthetic methods for preparing PEDOT nanoparticles have been reported including seed polymerization, emulsion polymerization and dispersion polymerization. There have been several reports related to PEDOT-coated particles and PEDOT hollow particles [43, 44], Dispersion polymerization has been applied for PEDOT-coated Polystyrene (PS) particle fabrication. lOOnm PS nanoparticles were used as the core material [44]. Poly aniline (PANi) nanofibers have been synthesized using interfacial polymerization without templates or functional dopants [45,46]. Scanning electron microscopy (SEM) images of PANi nanofibers are shown in Figure 14.3. 

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