Year

1993

Degree Name

Doctor of Philosophy

Department

Department of Chemistry

Abstract

A new membrane system, electrochemically controlled transport across conducting electroactive polypyrrole membranes has been demonstrated. This work describes the synthesis and characterisation of free-standing polypyrrole membranes, and their use for electrochemically controlled transport. This new membrane system is novel and exciting as it utilises the unique feature of electroactive polypyrrole resulting in dynamic controllable separations.

A range of free-standing polypyrrole membranes containing a series of sulfonated counterions have been successfully synthesised, by a range of methods including mixed counterions and multi-layer polymerisation.

The properties of the polypyrrole membranes were characterised using numerous techniques. The data indicated that ali membranes investigated are adequate for use in the studies of the electrochemical control of transport. The electrochemical properties of the polypyrrole, especially the ion incorporation and expulsion properties were characterised by cyclic voltammetry, chronoamperometry and chronopotentiometry. The results show that changes in the redox state of the polymer accompany the ion movement into and/or out of the polymer.

The hardware for a conducting polymer membrane transport system has been developed and some parameters affecting the performance of the system have been explored. It was found that the size of the membrane and the shape of the connection was important for the cell design, as well as the electrode arrangement which influenced the direction of the mass transport.

Electrochemically controlled transport across free-standing polypyrrole membranes has been investigated. The transport properties and separation capabilities of the membranes were determined using a range of chemicals. Results show that transport across the membrane can be switched on and off by application of an appropriate electrical potential. With this technique, the transport and separation properties of the membrane can be dynamically controlled in-situ.

The mechanisms for the transport of both electroinactive and electroactive species across the polypyrrole membrane have been explored.

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