Electron and proton conducting polymers: Recent developments and prospects

The use of polypyrrole (PPy)-based electronic noses (ENs) for environmental and industrial analysis has gained considerable momentum in the past decade. Toxic and non-toxic substances, such as ammonia, nitrogen oxides, carbon monoxide, sulphur dioxide, hydrogen sulphide, methane, oxygen, hydrogen, alcohols, phenol, benzene and water vapours have been successfully determined by PPy-based ENs in materials ranging from water and beverages to waste waters and sewage effluents. This article reviews the various research efforts that have been carried out over the past decade on the development of PPy-based ENs for environmental and industrial analysis. It also provides an overview on future prospects and development of ENs for broader applications in this area.

Polypyrrole-based electronic noses for environmental and industrial analysis

Characterization of synthetic membranes by Raman spectroscopy, electron spin resonance, and atomic force microscopy; a review

We have measured the thermoelectric power and conductivity as a function of temperature of a wide range of polypyrrole samples, including a film of soluble polypyrrole synthesized chemically, and wrinkled films synthesized using indium–tin oxide electrodes; other samples investigated include high-conductivity polypyrrole films synthesized at different temperatures and current densities, films grown on nonconducting substrates, and polypyrrole gas sensors. The thermoelectric powers are remarkably similar and metal-like for the medium and high conductivity samples but show nonzero extrapolations to zero temperature for wrinkled samples. The temperature dependence of conductivity tends to be greater for samples of lower conductivity. In contrast to polyaniline and polyacetylene, a crossover to metallic sign for the temperature dependence of conductivity at higher temperatures is not observed in any of our samples; the fluctuation-induced tunnelling and variable-range hopping expressions account for nearly all our conductivity data except for low-temperature anomalies. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 953–960, 1999

Thermoelectric power and conductivity of different types of polypyrrole

One of the most frequently used conducting polymers, polypyrrole, can take part in chemical processes with typical components of ambient media: oxygen, acids, bases, redox reactants, water, and organic vapors; it can also incorporate nonreactive ions and surfactants from solutions. The influence of such processes on changes of the polymer structure, composition and on possible degradation is analyzed. The benefits and disadvantages of such processes for analytical characteristic of polypyrrole based electrochemical sensors are considered. This discussion is focused on potentiometric ion sensors, where polypyrrole is either a receptor membrane or an ion-to-electron transducer placed between a solid state electrode support and a typical ion-selective membrane.

Chemical Reactivity of Polypyrrole and Its Relevance to Polypyrrole Based Electrochemical Sensors

Structure-conductivity relation for polypyrrole with a two-dimensional microscopic structure

Electronic and magnetic properties of polypyrrole films depending on their one-dimensional and two-dimensional microstructures

ESR studies of polypyrrole films with a two-dimensional microstructure

The adsorption of the endohedral fullerene, $\mathrm{La}@{\mathrm{C}}_{82},$ and the higher fullerene, ${\mathrm{C}}_{84},$ on $\mathrm{Si}(100)\ensuremath{-}2\ifmmode\times\else\texttimes\fi{}1$ is investigated using a scanning tunneling microscope (STM) operating in ultrahigh vacuum. Both molecules are found to adsorb directly above the dimer rows that are formed on the $\mathrm{Si}(100)\ensuremath{-}2\ifmmode\times\else\texttimes\fi{}1$ surface, as well as in trough sites midway between dimer rows. Adsorption above dimer rows, not observed for ${\mathrm{C}}_{60},$ is attributed to the larger radius of curvature of these fullerene cages. The response of $\mathrm{La}@{\mathrm{C}}_{82}$ to manipulation by the tip of the STM is also investigated. Molecules in either adsorption site may be manipulated with a threshold gap impedance \ensuremath{\sim}1.0 G\ensuremath{\Omega}. Owing to a near-commensurability between the molecular diameter of $\mathrm{La}@{\mathrm{C}}_{82}$ and the lattice constant of the Si(100) surface, close-packed arrangements of molecules may be formed.

L. Dunsch

Papers

Structure-conductivity relation for polypyrrole with a two-dimensional microscopic structure

Electronic and magnetic properties of polypyrrole films depending on their one-dimensional and two-dimensional microstructures

ESR studies of polypyrrole films with a two-dimensional microstructure

Adsorption and manipulation of endohedral and higher fullerenes on Si ( 100 ) − 2 × 1

Spectral signatures of positive and negative charged states in doped and photoexcited low band-gap polydithienothiophenes