Sulfonic Acid-doped Polyaniline Research Articles

Conductive blends of thermally dodecylbenzene sulfonic acid-doped polyaniline with thermoplastic polymers

In the present study, a conductive polyaniline-dodecyl benzene sulfonic acid (PANI-DBSA) complex, prepared by a thermal doping process, and its blends with thermoplastic polymers, prepared by melt processing, were investigated. PANI-DBSA characterization included conductivity measurements, morphology, crystallography, and thermal behavior. The blends' investigation focused on the morphology and the interaction between the components and on the resulting electrical conductivity. The level of interaction between the PANI and the matrix polymer determines the blend morphology and, thus, its electrical conductivity. Similar solubility parameters of the two polymeric components are necessary for a high level of PANI dispersion within the matrix polymer and, thus, enable the formation of conducting paths at low PANI content. The morphology of these blends is described by a two-structure hierarchy: (a) a primary structure, composed of small dispersed polyaniline particles, and (b) a short-range fine fibrillar structure, interconnecting the dispersed particles. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 243–253, 1997

Charge transport of camphor sulfonic acid-doped polyaniline and poly( o-toluidine) fibers: role of processing

We report the results of transport studies (temperature-dependent d.c. conductivity, thermopower, microwave frequency conductivity and dielectric constant for camphor sulfonic acid-doped polyaniline (PAN-CSA) and its methyl ring-substituted derivative, poly( o-toluidine) (POT-CSA) fibers prepared in solutions of m-cresol. The results for the PAN-CSA fiber are very similar to those for PAN-CSA film with the presence of some poorer conducting linkages. The POT-CSA fiber shows significantly higher conductivity with much weaker temperature dependence than the earlier studied hydrochloric acid-doped poly( o-toluidine) (POT-HCl) fiber and powder, indicating that it is much closer to the localization-delocalization boundary.

Tuning through the critical regime of the metal-insulator transition in conducting polymers by pressure and magnetic field

In the critical regime of the disorder-induced metal-insulator (M-I) transition, the temperature dependence of conductivity follows a power law, σ( T) ∝ T β , and the reduced activation energy function, W = T{ Δ(ln ϱ)/ ΔT}, is temperature independent ( W = β). We have observed transport in the critical regime for four conducting polymer systems: potassium-doped polyacetylene (C-CH) x ), iodine-doped polyacetylene (C-(CH) x ), phosphorous hexafluoride-doped polypyrrole (PPy-PF 6) and camphor sulfonic acid-doped polyaniline (PANI-CSA). For oriented polyacetylene doped with either potassium or iodine and for PPy-PF 6, W is temperature independent over a wide temperature range at ambient pressure; while, at high pressures (8–10 kbar), W has a positive temperature coefficient, indicating a pressure-induced crossover to the metallic regime. The enhanced interchain transport at high pressures causes the crossover from the critical regime to metallic behaviour. Application of a magnetic field (8 T) leads to a negative temperature coefficient of W for K-(CH) x , PPy-PF 6 and PANI-CSA, indicating a crossover from the critical regime to the insulating regime. Magnetic field-induced localization causes the crossover from the critical regime to insulating behavior. Thus, the electrical properties of conducting polymers can be tuned through the disorder-induced critical regime of the M-I transition into the metallic or insulating regimes by pressure and magnetic field, respectively.