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Water uptake and proton conductivity as a function of temperature were determined for three aromatic‐based, sulfonic acid‐bearing polymers, plus the perfluoroalkyl sulfonic acid Nafion® 117. Water uptake of submerged, equilibrated samples ranged from less than five water molecules per acid group for a high equivalent weight, sulfonated polyethersulfone to almost fifty waters per acid for a low equivalent weight, sulfonated polyetheretherketone. The most conductive aromatic‐based polymer, sulfonated polyphenylquinoxaline (S‐PPQ), had a room temperature conductivity of 9.8×10−3S/normalcm . about an order of magnitude less than that of a perfluoroalkyl sulfonic acid under identical conditions. The slope of the S‐PPQ Arrhenius conductivity plot was sufficiently steep that at 180°C, the proton conductivity, 1.3×10−1S/normalcm , was only a factor of two lower than that of Nafion under similar conditions. The lower conductivity of the aromatic‐based sulfonic acid polymers can be attributed to chain rigidity, lack of ion channels, and lower acidity. © 2000 The Electrochemical Society. All rights reserved.

TiO2 and WO3, with and without noble metal cocatalysts, were employed as photocatalytic surfacing agents to inhibit the attachment and growth of Oedogonium, a sessile, filamentous algae. It was demonstrated that coating a cement substrate with a dispersion of TiO2 powder held in a 10 wt % binder and irradiating with a combination of black light and fluorescent lamps could effect a 66% reduction in the growth of algae in comparison to the unprotected cement surface. Adding a 1.0 wt % loading of a noble metal such as Pt or Ir to the photocatalyst enabled an 87% reduction. The extent of inhibition was shown to be related to the amount of near-UV light contained in the irradiation source. The ability of the photocatalysts to inhibit algae correlated well with their ability to photooxidize d-(+)-glucose, building block of numerous biochemical polysaccharides, suggesting a nonspecific mechanism in the breakdown of cellular structures.

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