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Corrosion of synthetic metals
Author(s) -
Beck Fritz,
Michaelis Ronald
Publication year - 1991
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.19910420703
Subject(s) - polypyrrole , corrosion , polythiophene , conductive polymer , materials science , aqueous solution , polymer , electrochemistry , metal , conductivity , graphite , chemical engineering , doping , inorganic chemistry , chemistry , composite material , metallurgy , organic chemistry , polymerization , electrode , engineering , optoelectronics
Intrinsically conducting polymers as polypyrrole or polythiophene are new materials which have found widespread interest in the last ten years. Acceptor type doping leads to a solid, which is well comparable to graphite salts. For any kind of practical application of these polymers, the problem of adequate long term stability under environmental conditions must be solved. There are only a few measurements of conductivity vs. time in the air to derive conclusions in this direction, e.g. for polypyrrole. For the first time we present results of a systematic research into the understanding of corrosion phenomena, which occur in aqueous eletrolytes at different pH. Polypyrrole is selected as a well established candidate for a synthetic metal. Layers at a nominal thickness of 10μm on platinum, doped with BF 4 − anions, were investigated in aqueous buffers in the pH‐range of 1–13. Corrosion was determined via the measurement of the residual redox capacities. The material corroded after a rapid electrochemical mechanism and a relatively slow chemical mechanism. Both processes involve the radical cationic centers (polarons) in the solid. The time constants varied from 10 2 to > 10 8 s. Our findings allow for a better understanding of corrosion and selfdischarge of polypyrrole. Other conducting polymers were found to corrode after the same mechanism.