Water Sorption of Acid-Doped Polyaniline Solid Fibers: Equilibrium and Kinetic Response

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• 作者：Mayur M. Ostwal ; John Pellegrino ; Ian Norris ; Theodore T. Tsotsis ; Muhammad Sahimi ; and Benjamin R. Mattes
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2005
• 出版时间：September 28, 2005
• 年：2005
• 卷：44
• 期：20
• 页码：7860 - 7867
• 全文大小：267K
• 年卷期：v.44,no.20(September 28, 2005)
• ISSN：1520-5045

文摘

Measurements are reported for the sorption equilibrium and transport of water into commerciallyproduced polyaniline solid fibers from a 50% relative humidity air stream at ambient pressureof ~0.1 MPa and 300 K. The data have been collected using a single solid fiber morphology,PANION, but with different acid dopants used to change the polyaniline from its emeraldinebase (insulating), PANI-EB, to the emeraldine salt form (conducting), PANI-ES. The sorptionprocess was well described by unsteady Fickian diffusion into an infinite cylinder. The ratesand equilibrium capacities depended on the acid dopant utilized, but did not vary monotonicallywith the anion size or the acid strength. The measured adsorption/desorption water capacitiesvaried between 20 and 75 (mg of H₂O)/(g of dry polymer), depending on the anion dopant. TheBF₄^- and H₂PO₄^- doped fibers had the highest capacities. When the mass loading wasrecalculated on a (H₂O molecule/polymer repeat unit) basis, most doped fibers had a capacity of~0.5 H₂O per PANI-ES repeat unit. The exceptions were the BF₄^- and H₂PO₄^- doped fibers, forwhich the value was ~1. The apparent diffusion coefficients varied between 0.05 and 0.6 ×10^-12 m²/s and were usually larger during adsorption than desorption. The water capacity ofthe polyaniline solid fibers is at the upper end of what is usually observed for glassy polymersand provides the possibility for exploiting electronic conductivity, good mechanical strengthproperties, and desiccant qualities for advanced humidity control and sensing applications.