Dr. Tarmo Tamm, University of Tartu
Opponent: Prof. Hyacinthe Randriamahazaka, Paris Diderot University, France
Chemically synthesized conductive polymer (CP) electrodes were prepared for the following electrochemical modification by electrodeposition or electrochemical (re)doping. The principal goal of the research was to develop techniques and tentatively optimize the synthesis conditions to meet the needs of CP application areas with distinctively different expectations for the physical structure and ionic mobility of the CP electrodes. The conditions for the chemical and electrochemical synthesis were optimized for two CP application types: artificial muscles and high specific surface area electrodes. The presented techniques of chemical synthesis of the CP hydrogel electrodes and the novel combined chemical-electrochemical synthesis technique of CP on nonconductive substrates offer several advantages over traditional electrodes and preparation methods. The prepared materials and devices, based on widespread CPs polypyrrole and poly(3,4-ethylenedioxythiophene) (PPy and PEDOT), were characterized using primarily electrochemical methods.
It was shown that metal-free actuators, fabricated using the combination of chemical and electrochemical synthesis method effectively solved the delamination problem and facilitate the commercial production by avoiding the usage of precious metals, toxic organic solvents and vacuum techniques. The results of the electro-chemo-mechanical characterization indicate that the actuation performance of the prepared actuators compares well with the ones achieved using alternative techniques. In addition, the developed method was used for the preparation of a new type of liquid-operated tri-layer linear actuators.
Large specific surface area pristine PPy hydrogel electrodes were prepared by the oxidative chemical polymerization using affordable environment-friendly compounds and a simple one-step synthesis method. Large specific surface area PPy hydrogels could be used to relieve the power density limitations of CP-related energy storage devices, for controlled drug delivery devices, sensors, etc. Moreover, using PPy hydrogel as a precursor, derived PPy aerogels and carbonized aerogels were prepared, further widening the number of possible applications.