Characterization of polymeric films derived from α- and β-substituted N-vinylpyrroles

Electrochemical oxidation of N-vinyl-2-(2-thienyl)pyrrole (TP) and N-vinyl-2-(2-furyl)pyrrole (FP) in Bu4NClO4 + CH3CN solutions leads to the formation of polymeric films that exhibit voltammetric doping and de-doping waves similar to those of poly(pyrrole) and poly(thiophene). The films generated from the oxidation of TP and FP are stable upon electrochemical cycling for hundreds of scans in acetonitrile media, and in their dry, doped state exhibit conductivities in the similar to 10 mS cm(-1) range. Organic dielectric films can be formed from the oxidation of N-vinyl-4,5,6,7-tetrahydroindole (THI) in Bu4NClO4 + CH3CN solutions. Poly(THI) films prepared by scanning the potential nine times between 0 and +1.4 V vs. SSCE block the rotated-disk voltammetric response of decamethylferrocene and ferrocene by 94 and 48%, respectively. The observation that film permeabilities are dependent on redox probe molecular volume indicates that the films are not riddled with pin-hole defects. In addition, although the surface of the poly(THI) films is relatively hydrophilic, as noted by aqueous contact angle measurements, the permeability of the films toward redox probes dissolved in aqueous electrolyte is substantially lower than that found for probes in acetonitrile media. (C) 1998 Elsevier Science S.A. All rights reserved.