Conductivity of Poly(pyrrole)‐Poly(styrene sulfonate) Core–Shell Nanoparticles

Abstract

The dielectric properties of poly(styrene) nanoparticles decorated at their surfaces with poly(styrene sulfonate) [PSS] brushes and subsequently loaded with polypyrrole (PPy) were studied. These film-forming materials which may serve as hole-injection layers in organic light-emitting diodes, exhibit a core-shell-type morphology with a core of electrically insulating poly(styrene) and a shell consisting of a corona of PSS chains which form the matrix in which the electrically conducting complex of PPy and PSS is embedded. This conducting complex exists in form of domains of nanoscale dimensions. Thin compressed pellets of these nanoparticles were studied using mainly impedance spectroscopy. Measurements were carried out in the temperature range between 123 and 453 K and frequency range from 10(-1) to 10(6) Hz. While earlier studies were centered around the effect of polypyrrole volume fraction on the conductivity films and pellets composed of these nanoparticles, the present study reveals in which way the conductivity can be modified by exchange of the mobile inorganic counter ions of PSS. Besides the free-acid form (H(+)), the Li(+)-, Na(+)- and Cs(+)-salts of PSS were investigated. The PPy volume fraction was the same for all PPy/PSS core-shell nanoparticles. The distance for phonon-assisted hopping between next-neighbor polypyrrolium chains is influenced by the presence of these inorganic cations. For all samples containing PPy, a transition from insulating to conducting behavior in the range of 300-350 K was found. Using the fluctuation-induced tunneling model, the average tunneling distance, as well as the potential energy barrier separating neighboring conducting grains was estimated. Finally, a detailed analysis of the dielectric spectra suggests the localization length of the charge carriers to be about 0.33 nm.

Synthesis and characterization of polypyrrole doped with anionic spherical polyelectrolyte brushes

“…Results indicate that the room temperature electrical conductivity of PPy is 3.6 S/cm, however, PPy/ASPB nanocomposite shows a high value of conductivity (20 S/cm). Also, it is higher than those reported by literatures, including PPy-grafted multiwalled carbon nanotube (MWCNT) [25], polypropylene (PP)/ montmorillonite (MMT)/PPy nanocomposites [33], PPy/SiO 2 nanocomposite [34] and PPy/PSS coreshell nanoparticles [35]. Increase in magnitude of conductivity is consistent with the FTIR and Raman spectra results.…”

Synthesis of substituted meso-tetraphenylporphyrins in mixed solvent systems

“…The acids (including Lewis acid and Brønsted acid), as reported, 31 played a catalytic role in the condensation of benzaldehyde and pyrrole. 38 But then the stronger acidity was liable to make pyrrole form straight-chain pyrrole polymers, 39 thus, almost all black intractable mixtures but the TPPH 2 product were obtained in formic acid and valeric acid as the mixed solvents.…”

Ehrendoktorwürde: G. Wenger / Credit‐Suisse‐Preis: D. Hilvert / Kapitza‐Medaille in Gold und Jayne Prize Lectureship: J. M. Thomas

“…Wegner gehört derzeit dem Editorial Board von Chemistry—A European Journal an und war 1985–1994 Mitglied des Kuratoriums der Angewandten Chemie . In dieser Zeitschrift hat er die EPR‐Charakterisierung thermoresponsiver dendronisierter Polymere beschrieben1a und in ChemPhysChem die Leitfähigkeit polymerbasierter Kern‐Schale‐Nanopartikel 1b…”