Premium
Estimation of charge trapping in bilayers of coducting polymers composed of polypyrrole and poly( N ‐methylpyrrole)
Author(s) -
Maksymiuk Krzysztof
Publication year - 1996
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.1140080711
Subject(s) - polypyrrole , bilayer , perchlorate , cyclic voltammetry , polymer , conductive polymer , materials science , trapping , analytical chemistry (journal) , lipid bilayer , voltammetry , redox , polymer chemistry , chemistry , ion , membrane , electrochemistry , electrode , inorganic chemistry , organic chemistry , composite material , polymerization , ecology , biochemistry , biology
Charge trapping effects were studied in bilayers of conducting polymers composed of poly( N ‐methylpyrrole) (PMPy) and polypyrrole (PPy), by comparing redox charges of the polymer [ Q (ox/red)] obtained by integration of cyclic voltammetric and chronoamperometric curves for single films and bilayers with variable thickness of both components. Charge trapping factors, TF , for PMPy(inner layer)/PPy(outer layer) bilayers were determined using the definition: TF = 1 ‐ Q (ox/red) PPy bil / Q (ox/red) PPy where Q(ox/red) PPy bilis redox charge of PPy in the bilayer, Q(ox/red) ppy relates to the charge for a single PPy film of the same thickness as that in the bilayer. Since the formal potential of PMPy is higher than that of PPy, the outer PPy film cannot be entirely reduced due to low conductivity of PMPy at negative potentials. The estimated charge trapping factor is independent of the outer layer thickness, it depends, however on the thickness of the inner film. For the reverse sequence of polymers, PPy/PMPy, charge trapping was not observed. Modification of the outer PPy layer by immobilized poly(4‐styrenesulfonate) anions changes the response of the bilayer due to low permeability of the cation‐exchanging outer polymer to anions. Therefore perchlorate anions compensating charge of PMPy film were found to be entrapped in the polymer matrix under conditions of cyclic voltammetry.