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Strong effects of counterions on the electrochemistry of poly( N ‐methylaniline) thin films
Author(s) -
Planes Gabriel A,
Miras María C,
Barbero Cesar
Publication year - 2002
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.830
Subject(s) - counterion , electrochemistry , electrolyte , polyaniline , ion , conductive polymer , polymer , chemistry , electrochemical potential , salt (chemistry) , inorganic chemistry , materials science , chemical engineering , electrode , organic chemistry , polymerization , engineering
Abstract Poly( N ‐methylaniline) thin films show different cyclic voltammetric behaviour when cycled in HClO 4 , HBF 4 , HCl or HNO 3 . While in the first two acids the film shows profiles peak potentials similar to those of polyaniline, profiles in HCl and HNO 3 show higher peak potentials for oxidation and a different shape. The free energy for the process, calculated from the oxidation peak potential, shows a linear correlation with the free energy of hydration of the anions present in the test solution. An energy cycle for the oxidation process is proposed to explain the results. The reaction mechanism assumes that anions have to lose their hydration shell to form the polymer salt during electrochemical oxidation of the films. Electropolymerization also depends on the anion present in the solution. While this is possible with low hydration energy anions (ClO 4 − , BF 4 − ), it is difficult or impossible when the electrolyte solution contains other anions (Cl − , NO 3 − ) where a higher oxidation potential of the preformed polymer is observed. © 2002 Society of Chemical Industry