Nanofiber Seeding is a process to control the bulk

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

of chemically synthesized conducting polymers. Typically, catalytic amount of nanofiber seeds are added in prior to onset of nanofiber seeding polymerization (reaction), where seeds are served as the 'morphology directing agent' rather than conventional templates (see hard or soft templating methods).

Description

A new synthetic approach, called nanofiber seeding, was developed to control the bulk morphology of chemically synthesized electronic organic polymers. Bulk quantities of

nanofiber Nanofibers are fibers with diameters in the Nanometre, nanometer range (typically, between 1 nm and 1 μm). Nanofibers can be generated from different polymers and hence have different physical properties and application potentials. Examples ...

s of

conducting polymer Conductive polymers or, more precisely, intrinsically conducting polymers (ICPs) are organic polymers that conduct electricity. Such compounds may have metallic conductivity or can be semiconductors. The main advantage of conductive polymers i ...

s such as

polyaniline Polyaniline (PANI) is a conducting polymer and organic semiconductor of the semi-flexible rod polymer family. The compound has been of interest since the 1980s because of its electrical conductivity and mechanical properties. Polyaniline is one ...

, can be synthesized in one step without the need for conventional templates, surfactants, polymers, or organic solvents. Conventional oxidative polymerization approaches to nanostructured conducting polymers include the use of hard template zeolites, opals, and controlled pore-size membranes, or soft template such as polymers and surfactants. A “template-free” approach has also been described in which the use of large organic anions results in polyaniline nanofibers and nanotubes having average diameters in the 650-80 nm range. Standard synthesis of polyaniline yields

granular Granularity (also called graininess) is the degree to which a material or system is composed of distinction (philosophy), distinguishable pieces, granular material, "granules" or grain, "grains" (metaphorically). It can either refer to the exten ...

morphology. However, if the conventional reaction is seeded by 1-4 mg (seed quantities) of added pre-synthesized polyaniline

nanofibers Nanofibers are fibers with diameters in the Nanometre, nanometer range (typically, between 1 nm and 1 μm). Nanofibers can be generated from different polymers and hence have different physical properties and application potentials. Examples ...

, (nanofiber seeds could be prepared from interfacial polymerization) the bulk morphology changes dramatically from granular to nano-fibrillar. Furthermore, increased capacitance values were observed in polyaniline nanofibers synthesized by the nanofiber seeding approach. Oxidative polymerization can be also seeded by other nanostructure materials such as vanadium pentoxide nanofibers, where V2O5 nanofibers (i) Rapidly initiate fibrillar polymer growth (ii) Slowly dissolve in aq. 1.0 M HCl, which eliminates template removal steps. Hence only catalytic amounts (4mg) V2O5 nanofibers are needed prior to onset of polymerization, which significantly change the bulk morphology of the polymer precipitate. Moreover, single-walled carbon nanotube and nano fibrous hexapeptide can be also used as templating seeds. This method can be extended to all major classes of conducting polymers, including

polypyrrole Polypyrrole (PPy) is an organic polymer obtained by oxidative polymerization of pyrrole. It is a solid with the formula H(C4H2NH)nH. It is an intrinsically conducting polymer, used in electronics, optical, biological and medical fields. Histor ...

PEDOT Poly(3,4-ethylenedioxythiophene) (PEDOT or PEDT; ''IUPAC'' name poly(2,3-dihydrothieno ,4-''b''1,4]dioxane-5,7-diyl)) is a conducting polymer based on 3,4-Ethylenedioxythiophene, 3,4-ethylenedioxythiophene or EDOT. It was first reported by Bay ...

and other polythiophenes etc. Nanofiber seeding is a convenient approach to obtain thin, substrate-supported, transparent films of nanofibers of conducting polymers without requiring any bulk processing steps.

References

# ''Synthesis of Polyaniline Nanofibers by ‘Nanofiber Seeding’'' Xinyu Zhang, Warren J. Goux, Sanjeev K. Manohar J. Am. Chem. Soc.; 2004; 126(14) pp 4502-4503; (Communication) # ''Chemical Synthesis of PEDOT Nanofibers’'' Xinyu Zhang, Alan G. MacDiarmid, Sanjeev K. Manohar Chem. Comm.; 2005; 42 pp 5328-5330; # ''Bulk Synthesis of Polypyrrole Nanofibers by a Seeding Approach’'' Xinyu Zhang, Sanjeev K. Manohar J. Am. Chem. Soc.; 2004; 126(40) pp 12714-12715; (Communication) {{doi, 10.1021/ja046359v Polymer chemistry Conductive polymers