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1.3 PHYSICAL SCIENCES
An attempt has been made to improve the physical-chemical properties of conducting polymers by switching from aqueous solutions towards ionic liquids as novel electrolytic media in order to fabricate novel electrochromic materials. Formation and electrochemical characterization of Poly (2,3,5,6- Tetrafluoroaniline) (PTFA) was performed in aqueous solutions. The optical response was observed in order to establish the electrochromic properties of this material. Electrochromic activity of PTFA conducting polymer in aqueous conditions was investigated. Results indicated a slow colour change of 40 seconds, from delicate orange to a much intense orange colour. Electrochemical copolymerization of two monomers pyrrole (Py) and 3,4- ethylenedioxythiophene (EDOT) was performed in an ionic liquid employing a novel ‘micro-cell’ in order to use the materials efficaciously. Characterization of the copolymers electrochemical features was performed for different Py : EDOT ratios (1:2, 1:1, 2:1) in both aqueous and ionic liquid electrolytes. A series of spectroscopic and microscopic studies were also carried out in order to prove the copolymer formation. All three copolymers presented different absorbance spectra, while the FTIR were not very clear. However, the morphology investigation highlighted the different features of copolymers which showed various distributions of globules, pores and holes. Ionic movement between aqueous phase and ionic liquid was studied, and a model was developed to describe the interfacial processes occurring between two immiscible liquid phases. In the present work the Ferrocene ion transport across the ionic liquid / water interface was studied experimentally and in comparison to a model for a thin film of ionic liquid. Results obtained from experimental and modelling data had similar trends of increase in the peak to peak separation with increased scan rate, but the peak to peak separation in the experimental was larger. A new, cost-effective prototype of ‘micro-sandwich electrochromic cell’ was fabricated, based on an ‘ion jelly’ electrolyte. The ‘ion jelly’ solid state electrolyte was a successful replacement for the costly ionic liquids. This prototype of electrochromic cell showed dark-bluish and light-blue colours upon redox switch, but optimization is needed in order to reach the desirable features of a high-performance electrochromic device.
Astratine, L. (2012). Preparation and Characterization of Conducting Polymer Materials for Electrochromic Devices. Doctoral Thesis. Dublin Institute of Technology. doi:10.21427/D73G67