| A new synthetic approach, called 'nanofiber seeding', was developed to control the bulk morphology of chemically synthesized electronic organic polymers. This method allows to synthesize bulk quantities of nanofibers of electronic polymers in one step. Conducting polymers like polyaniline, polypyrrole, poly-3,4-ethylenedioxythiophene (PEDOT) etc. are typically synthesized by chemical oxidative polymerization of the corresponding monomers using (NH4)2S2O 8 as the oxidant.; When the reaction is carried out in the presence of 2-4 mg of added nanofiber seeds, the bulk morphology changes dramatically from granular to nano-fibrillar. The V2O5 nanofiber seeds can be extended to all major classes of conducting polymers. Nanofibers of polyaniline, polypyrrole, polythiophene, and PEDOT are synthesized in bulk quantities in their electronically conducting form.; Whereas seed quantities of added nanofibers yielded polymer nanofibers, stochiometric amounts of added nanofibers yielded polymer nanotubes. For example, when stochiometric amounts of V2O5 nanofibers are used during the polymerization of pyrrole, V2O5-polypyrrole core-sheath structure is formed. The V2O5 in the pore dissolves readily in dilute aqueous acids during the purification step, yielding hollow polypyrrole nanotubes. As-synthesized, doped polypyrrole nanotubes spontaneously reduce noble metal ions to the corresponding metal nanoparticles and deposit on the surface of the tubes which then may migrate to the pore to form a coaxial cable.; Conducting polymer nanotubes can also be synthesized by emulsion polymerization. For example, reverse emulsion polymerization method was developed to chemically synthesize bulk quantities of microns long, tubes of electrically conducting PEDOT having tube diameter in the range 50-100 nm. Composites of PEDOT nanotubes and noble metals/oxides can be readily synthesized using both in-situ and post-synthesis methods. The noble metal nanocomposites have potential application in the design of next generation catalyst systems including vapor and analyte sensors. |
