Composites of carbon nanotubes and conducting polymers

• Main Author: Hughes, M.
• Published: University of Cambridge 2003
• Subjects: 541.37
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604735

Carbon nanotubes and conducting polymers are both interesting for their unique electrochemical properties that make them well suited to use in electrochemical capacitors (sources of high power pulses of electrical energy) and actuators (artificial muscles). In the case of carbon nanotube films, it is their high surface area and electrical conductivity that makes them attractive, particularly in terms of their fast response times. In contrast, the redox chemistry of conducting polymers enables them to achieve large charge storage capacities and dimensional changes in response to potential cycling (often several orders of magnitude larger than those of carbon nanotubes). This thesis reports on the structure and electrochemical properties of composites of multi-walled nanotubes and conducting polymers (polypyrrole and poly(3-methylthiophene)) in addition to their performance in electrochemical capacitors and actuators. The composite film growth conditions were manipulated so as to merge the desirable properties of multi-walled nanotubes with those of conducting polymers. The results composite films were capable of charge storage capacitances, response times and cycle lives superior to those of pre conducting polymer films produced and tested using similar conditions. The alignment, concentration, production route, dimensions and chemical treatment of the carbon nanotubes were all found to play an important role in determining the nanostructure, doping and electrochemical behaviour of the composite films produced. The electrochemical capacitors tested illustrated the power and energy gains that are possible when using carbon nanotube-conducting polymer composite films. Composite film actuators made from multi-walled nanotubes and polypyrrole demonstrated the importance of orienting the nanotubes perpendicular to the desired direction of actuation in order to improve actuation kinetics (through increased electrical conductivity) without constraining actuation of the conducting polymer.