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Effect of pH, Fluorination, and Number of Layers on the Inhibition of Electrochemical Reactions by Grafted, Hyperbranched Poly(acrylic acid) Films
Author(s) -
Zhao Mingqi,
Bruening Merlin L.,
Zhou Yuefen,
Bergbreiter David E.,
Crooks Richard M.
Publication year - 1997
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.199700032
Subject(s) - passivation , chemistry , dielectric spectroscopy , electrode , electrochemistry , acrylic acid , cyclic voltammetry , polymer chemistry , chemical engineering , layer (electronics) , inorganic chemistry , organic chemistry , polymer , copolymer , engineering
We report the electrode‐passivation properties of both fluorinated and unmodified hyperbranched poly(acrylic acid) (PAA) films as a function of pH and the number of PAA layers. Both cyclic voltammetry and ac‐impedance spectroscopy show that the extent of blocking increases with the number of layers, regardless of the solution pH. However, passivation resulting from unfluorinated PAA films decreases with increasing pH, while passivation due to fluorinated films increases with increasing pH. Three‐layer fluorinated films can increase the charge transfer resistance of the electrode by up to a factor of 6 × 10 4 . Although Randles' equivalent circuit can be used to model the electrochemistry of electrodes covered with unfluorinated PAA, fluorinated PAA‐coated electrodes often require additional circuit elements due to the high resistance of these hydrophobic films.