| Abstract
| - The synthesis of poly(vinyl hydroquinone), PVHQ, via stable free radical polymerization(SFRP) to give a low-dispersity (1.5) material is described. The electrochemical propertiesof the resulting material deposited as films onto glassy carbon electrodes have beeninvestigated by cyclic voltammetry. In aqueous acetic acid solution, it was found that as theamount of material ostensibly deposited (Γtheo) increased the ratio Γobs/Γtheo (where Γobs andΓtheo represent the measured and the theoretical surface coverage values, respectively)drastically decreased, indicating that a significant fraction of the quinone sites areelectrochemically inactive as the film thickness increases. This was attributed to a smallelectron transfer rate constant and to the fact that the electron transfer is coupled to protontransfer, so the hydrophobicity of the polymer backbone might adversely affect theaccessibility of protons. Using Laviron's theory, the electron-transfer rate constant and thetransfer coefficient were determined to be 2.1 s-1 and 0.5, respectively, for a PVHQ film(Γobs = 4.3 × 10-10 mol cm-2) on a glassy carbon electrode in 0.10 M acetic acid solution. Theformal potential of the PVHQ film shifted with pH at a rate of 59 mV/pH unit up to pH 6.At higher pH values, the slope decreased to ca. 30 mV/pH unit, suggesting a two-electron/one-proton reaction. The surface pKa value for the first deprotonation reaction was estimatedto be 7.8.
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