Doping electroactive composites

The one-step method, which uses an electrolyte solution that contains both the pyrrole monomer and the host polymer. Ehiring the electropolymerization process there is an incorporation of the inert polymer within the electroactive polymer. If the host polymer is an electrolyte, the electropolymerization process leads directly to doped conducting composite films. 

The speed of p- and n-type doping and that of p-n junction formation depend on the ionic conductivity of the solid electrolyte. Because of the generally nonpolar characteristics of luminescent polymers like PPV, and the polar characteristics of solid electrolytes, the two components within the electroactive layer will phase separate. Thus, the speed of the electrochemical doping and the local densities of electrochemically generated p- and n-type carriers will depend on the diffusion of the counterions from the electrolyte into the luminescent semiconducting polymer. As a result, the response time and the characteristic performance of the LEC device will highly depend on the ionic conductivity of the solid electrolyte and the morphology and microstructure of the composite. 

Willner and coworkers demonstrated three-dimensional networks of Au, Ag, and mixed composites of Au and Ag nanoparticles assembled on a conductive (indium-doped tin oxide) glass support by stepwise LbL assembly with A,A -bis(2-aminoethyl)-4,4 -bipyridinium as a redox-active cross-linker.8 37 The electrostatic attraction between the amino-bifunctional cross-linker and the citrate-protected metal particles led to the assembly of a multilayered composite nanoparticle network. The surface coverage of the metal nanoparticles and bipyridinium units associated with the Au nanoparticle assembly increased almost linearly upon the formation of the three-dimensional (3D) network. A coulometric analysis indicated an electroactive 3D nanoparticle array, implying that electron transport through the nanoparticles is feasible. A similar multilayered nanoparticle network was later used in a study on a sensor application by using bis-bipyridinium cyclophane as a cross-linker for Au nanoparticles and as a molecular receptor for rr-donor substrates.8... 

On the other hand, liquid phase deposition (LPD) has been demonstrated as a flexible wet chemical method for preparing metal oxide nanostructured films on electrode surfaces. By the LPD process, electroactive titanium dioxide (Ti02) films were prepared on graphite, glassy carbon and ITO. The electrochemical properties of such LPD Ti02 films were dependent upon the film thickness controlled by the deposition time. The LPD technique was easily combined with other techniques, e.g., seed-mediated growth, which could provide metal/metal oxide composite nanomaterials. Moreover, hybrid nanostructured films were facilely obtained by doping dyes, surfactants and other... 

E.V. Ovsyannikova, O.N. Efimov, E.P. Krinichnaya, and N.M. Alpatova, Cathodic doping of thin-layered composites. Formed by electroactive polymers and rubbed single-walled carbon nanotubes, Rus. J. Electrochem., 43, 1064-1068 (2007). 

Ternary composites with electroactive components were also discussed by Gomez-Romero and coworkers in one of their recent publications [48]. The ternary composites consisted of doped-polyaniline (PANI) or doped-polypyrrole (Ppy) intercalated into V2O5 xerogels. The dopant anion for the conducting polymers was [Fe(CN)g] (HCF), derived from H3Fe(CN)6. More specifically, the synthesis of Ppy/HCF/V205 and PANI/HCFA 20s was carried out by treating the monomer (aniline or pyrrole)... 

A mixture of dimethyl sulfoxide/tetrahydrofuran (THE) was used to obtain homogeneous blended nanofibers of an HCl-doped poly(aniline-co-3-aminobenzoic acid) (3ABA-PANI) copolymer and poly(lactic acid) (PLA) for tissue engineering. Since the solvent system dimethyl sulfoxide (DMS0)/THF (50 50) is quite difficult to be removed from the nonwoven mats, the authors used a heated collector to facilitate solvent removal. This procedure can be considered essential in cases where nonwoven fiber mats will be used in cell growth. Besides, composite electroactive fibers achieve lower con-... 

Aleshin, A. N., Mironkov, N. B., Suvorov, A. V., Conklin, J. A., Su, T. M., and Kaner, R. B., Electrical properties of ion implanted and chemically doped polyaniline films, in Materials Research Society Symposium Proceedings on Electrical, Optical and Magnetic Properties of Organic Solid State Materials III, Vol. 413, 1996, p. 609. Cameron, D. A., and Reynolds, J, R., Conducting molecular composites of polypyrrole with electroactive polymeric dopant ions, ACS Proc., 37, 684 (1996). 

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