Electrochromism, polythiophene

Alkan, S., C.A. Cutler, and J.R. Reynolds. 2003. High quality electrochromic polythiophenes via BF3 Et20 electropolymerization. Adv Funct Mater 13 331-336. 

Polymers, large molecules made up of smaller molecules in a repeating pattern, are used for many electrochromic materials. Conjugating polymers, which have alternating single and double bonds, are particularly suitable. Figure B shows the electrochemical oxidation of the conjugated polymer, polythiophene. Oxidation (in which electrons are removed) produces a semiconductive polymer. The neutral (unoxidized) polythiophene is red in color, whereas the semiconductive polythiophene (oxidized) is blue. In their neutral... 

Polythioether polymer, 22 40-41 Polythioethers, 23 704 Polythionic acids, 23 641 Polythiophene(s), 22 207t 23 708 conducting, 7 517-520 7 523, 527 electrochromic material, 6 572t, 575, 581t... 

All inorganic electrochromes exist in the solid state in both the colourless and coloured states, e.g. Prussian Blue and tungsten trioxide. Conducting polymers such as polyanilines, polypyrroles and polythiophenes also fall into this class of electrochromes (see 1.5.3.5). 

The other important electrochromic polymers are the polypyrroles and polythiophenes, obtained by polymerisation of the parent pyrrole and thiophene or, more importantly, their 3,4-substituted derivatives. The most widely studied of these two classes of polymers in electrochromic outlets are the poly thiophenes, which are readily synthesised by the reaction of the substituted monomer with FeClj in chloroform solution. The colour change properties of a variety of poly thiophenes in the presence of a counter-ion are shown in Table 1.14. ... 

Table 1.14 Electrochromic colour change properties of polythiophenes (Reproduced with permission of Wiley-UCH)...

Thiophene polymers, in particular, alkyl-substituted polythiophenes (PTH), are some of the conducting polymers being most actively investigated at present. This fact is attributable to their high degree of processability, environmental stability [49, 50] and, in some cases, ability to exhibit reversible electrochrom-ism [51] and thermochromism [52]. Another important family of sulfur-... 

The rationale for preparing this hybrid copolymer was to combine the desirable properties of polyaniline with those of polythiophene. For example, polythiophene has demonstrated thermo- and electrochromism, solvatochromism, luminescence, and photoconductivity while polyaniline has demonstrated reversible protonic dupability, excellent redox re-cyclability, and chemical stability. 

Another interesting application that uses the dynamic properties of conducting polymers is electrochromic devices.44,45 46 47 An electrochromic device based on polypyrrole is shown in Figure 1.8. The polypyrrole changes from colorless to black when it is oxidized by the application of positive potentials. Similarly, polythiophene and polyaniline undergo distinct color changes when an electrical potential is applied. 

Conducting polymers such as polyacetylene, polypyrrole, polyaniline, polythiophene, etc. have been actively studied for use in various fields due to their interesting properties batteries,46 electrochromic displays,47 materials for supercapacitors,48 corrosion protection,49 protecting layers for static electricity,50 materials for organic electroluminescence displays,51 sensing materials,52 etc. Polypyrrole is reported to be extremely rigid, with a semi-crystalline structure. 

A polythiophene anode in an aqueous electrolytic system, showed irreversible changes at a potential beyond 0.9 V on repeated reduction, suggesting that the breakdown into lower oligomers occurs, as evident from its Raman spectra [268]. However, the loss of electroactivity, electrical conductivity, electrochromic properties, mechanical properties, compact morphology... 

An electrochromic display (BCD) is a thin solid state device that changes color reversibly when subjected to a small electrical potential. Since the doping processes of certain conducting polymers are accompanied by changes in the color, this effect has been conveniently exploited in the realization of BCD devices. Thin films of a conducting polymer polythiophene, for example, are red in the doped state and deep blue in the undoped state. 

Gadgil, B., Damlin, R, Aaritalo, T, and Kvarnstrom, C. [2014], Electrosynthesis of viologen cross-linked polythiophene in ionic liquid and its electrochromic properties, Electrochim. Acta, 133, pp. 268-274. 

Polythiophenes for Electrochemical and Optical Sensors Metal-containing Polythiophenes Polythiophenes for Electrochromic Devices Polythiophenes for Electronic Devices... 

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