Ion transport in conducting polymers doped with electroactive anions examined by EQCM

Transport properties and stability of ionic species in films of conducting polymers polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDT) were examined by electrochemical quartz crystal microgravimetry (EQCM) experime nts. The mobility of ions in these polymers were greatly affected by the mo de of polymerization with which the polymer film was prepared, as well as b y the structure of the ions. When the conducting polymers were doped with m acrocyclic anions, phthalocyanine and porphyrin derivatized with sulfonate anionic groups, these anions were not expelled from the PPy or PEDT films b y extensive potential cycles. Heteropolytungstate ions have partial mobilit y in the polymers and were expelled by negative potential sweeps applied to the films that were formed by electropolymerization at a constant potentia l or constant current. Polymer films formed with alternating potential prog rams showed drastically diminished permeability to anions. By forming a pol ymer film with cyclic potential sweeps or square wave potentials, it was po ssible to examine transport of other ions without complications due to the transport of the initial dopant ions. (C) 2000 Elsevier Science Ltd. All ri ghts reserved.