Accession Number : ADA328614

Title :   Effect of pH, Fluorination, and Number of Layers on the Inhibition of Electrochemical Reactions by Grafted, Hyperbranched Poly(acrylic acid) Films.

Descriptive Note : Technical rept. 1 Jun-31 Jul 96,

Corporate Author : TEXAS A AND M UNIV COLLEGE STATION DEPT OF CHEMISTRY

Personal Author(s) : Zhao, Ninggi ; Bruening, Merlin L. ; Zhou, Yuefen ; Bergbreiter, David E. ; Crooks, Richard M.

PDF Url : ADA328614

Report Date : 31 JUL 1997

Pagination or Media Count : 35

Abstract : 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 X 10(exp 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.

Descriptors :   *CORROSION INHIBITION, *ELECTROCHEMISTRY, FILMS, CHARGE TRANSFER, VOLTAMMETRY, PH FACTOR, HYDROPHOBIC PROPERTIES, FLUORINATION, EQUIVALENT CIRCUITS, PASSIVITY, ACRYLIC ACID.

Subject Categories : Physical Chemistry
      Polymer Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE