Abstract
Rotating disk voltammetry and ionic conductivity measurements have been used to investigate the transport of I{sup {minus}}, Cl{sup {minus}}, and Fe(CN){sub 6}{sup 4{minus}} in poly(1-methyl-3-(pyrrol-1-ylmethyl)pyridinium) (polyMPMP{sup +}) films. The diffusion coefficient for I{sup {minus}} in polyMPMP{sup +} is strongly dependent on the solvent. In water D{sub iodide,pol} is very high (1.5 {times} 10{sup {minus}7} cm{sup 2}s{sup {minus}1}) due to significant swelling of the polymer, while in acetonitrile it is over 2 orders of magnitude lower. PolyMPMP{sup +} is significantly more permeable than polypyrrole in water, especially to Fe(CN){sub 6}{sup 4{minus}}. It is over 1000 times more permeable than the reduced form of polypyrrole. However, in acetonitrile polypyrrole (oxidized) is the more permeable of the two polymers. This difference is explained in terms of the degree of solvation and swelling of the polymers in the two solvents. It is concluded that solvation/swelling is much less significant in acetonitrile.
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