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Membranes containing cylindrical metal nanotubules that span the complete thickness of the membrane are described. The inside radius of the nanotubules can be varied at will; nanotubule radii as small as 0.8 nanometer are reported. These membranes show selective ion transport analogous to that observed in ion-exchange polymers. Ion permselectivity occurs because excess charge density can be present on the inner walls of the metal tubules. The membranes reject ions with the same sign as the excess charge and transport ions of the opposite sign. Because the sign of the excess charge on the tubule can be changed potentiostatically, a metal nanotubule membrane can be either cation selective or anion selective, depending on the potential applied to the membrane.

Growing environmental concerns regarding the use of heavy metals in coating formulations have lead to a new coating strategy employing inherently conducting polymers (ICPs), such as polyaniline (PANI), as a key component. The principal potential advantage offered by the ICP coating technology is toleration of pinholes and minor scratches. This paper describes the application of the scanning reference electrode technique (SRET) to the study of PANI coatings on carbon steel. SRET results demonstrate that conductive PANI "passivates" pinhole defects in coatings on carbon steel. In addition, it is shown that phosphonic acid salts of PANI are more effective for corrosion protection than sulfonic acid salts. A model is proposed which entails passivation of the metal surface through anodization of the metal by PANI and formation of an insoluble iron-dopant salt at the metal surface.

Nanotubules and nanofibrils of polypyrrole were chemically synthesized using the pores of nanoporous polycarbonate membrane filters as templates. We have previously shown that such "template-synthesized" nanofibrils of polypyrrole can have enhanced conductivities relative to more conventional forms of the polymer (e.g., thin films). Furthermore, we have shown that this enhancement in conductivity is critically dependent on the diameter of the nanofibrils; the narrowest diameter fibrils show the greatest enhancements in conductivity.In this paper we explore the genesis of this enhancement in conductivity by determining the relative conjugation lengths in the polypyrrole fibrils using FTIR and UV-visible-NIR spectroscopies. Using polarized infrared absorption and FTIR spectroscopies, we have followed the evolution of polymer chain orientation and conjugation length with polymer chain growth on the pore wall of the template membrane. On the basis of these results, we have proposed a bilayer model to explain the enhancement in conductivity and its strong dependence on fibril diameter.

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