Doctoral Dissertations

Date of Award

8-1990

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Chemistry

Major Professor

James Q. Chambers

Committee Members

E. L. Wehry, J. D. Kovac, E. E. Stansbury

Abstract

The field of polymer modification of electrode surfaces has been intensely researched in the past few years, with much effort being directed towards the detection and quantitation of trace ions in aqueous solutions. The purpose of this thesis has been to study the effect of the incorporation of silver(I) ion into a polymeric-7,7',8,8'-tetracyanoquinodimethane (TCNQ) matrix, using either polyester-TCNQ or a polyurethane- TCNQ. Silver was chosen as a test marker because of its simple one-electron electrochemistry, and because of recent interest in silver-TCNQ optically-active complexes. Cyclic voltammetry was used to collect data measuring the amount of incorporation of silver(I) ion into the polymer matrix, while spectroscopic methods were used to ascertain the position and oxidation state of the silver within the film. Silver(I) ion was incorporated into the polymer films, following the timed reduction of the film in aqueous electrolytes, by treatment with silver nitrate solutions varying in concentration from 1.0E-1M to 1.0E-8M. Results show that silver(I) ion can be incorporated into polymer-TCNQ films from low ionic strength, quiescent aqueous solutions, conditions which mimic many environmental systems. Silver(I) ion can be detected at concentrations as low as 1.0E-8M after twenty minutes, a detection limit roughly three orders of magnitude better than standard ion selective electrodes. Data also suggest that the procedure outlined could be applied to the detection of mercury(II) ion, and possibly other ions as well. Spectroscopic information suggests that the silver exists in the film as dispersed silver metal, probably in the form of stable metal clusters. Finally, this thesis presents some preliminary data on the effect of a magnetic field upon the electrochemical properties of the polymer-TCNQ films. The data indicate that the magnetic field can affect the polymer structure of the film, producing changes in the polymer electrochemistry dependent on the rigidity of the polymer backbone.

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