Polymer electrochromic materials polythiophene

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... 

The alteration of the optical properties for an electrochromic material involves the insertion or extraction of charge. These polymers can be classified into three types, depending on their specific optical states (1) absorption/transmission-type materials made of metal oxides, viologens or polymers such as PEDOT, including at least one colored and one bleached state for smart windows, (2) display-type materials made of polythiophenes without a transmissive state and (3) materials composed of blends, laminates and copolymers including more than two colored states [7],... 

Thiophene-based polymers exhibit high conductivities in their doped states, offering good processability and interesting optical and electronic properties. Due to their exhibition of diverse color variations and their high contrast ratios, functionalized polythiophenes have become popular as electrochromic materials. 

The bandgap of PEDOT ( g = 1.6-1.7 eV)itselfis 0.5 eV lower than polythiophene, which results in an absorbance maximiun in the NIR region. Compared to other substituted polythiophenes, these materials exhibit excellent stability in the doped state which is associated with high conductivity. Doped PEDOT is almost transparent in the visible region (with a sky-blue tint) and the neutral polymer is deep blue. Because PEDOT and its alkyl derivatives are cathodically-coloring electrochromic materials, they are suitable for use with anodically-coloring conducting polymers in the construction of dual polymer ECDs (63). 

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. 

Electrochromism describes a color change as a result of an applied potential, typically via an electrochemical mechanism. Many electrochemically switchable materials such as polythiophenes and polyaniline have this capability. Table 4.1 shows a very few of the materials and colors available today. Other nonpolymeric materials such as viologens [10] offer a higher contrast, but are not themselves conducting and therefore must be combined with a conducting polymer or another conducting... 

K-Conjugated polymers and oligomers are organic materials with many interesting and useful properties [1, 2], Examples of this class of materials include polyacetylene, polythiophene, polypyrrole, poly(phenylenevinylene) and their derivatives. Electronic conductivity, luminescence and nonlinear optical behavior are all observed in these materials and these properties have been exploited in applications such as electroluminescent devices (polymer light-emitting devices or PLEDs), electrostatic coatings, electrochromic windows, chemical sensors and memory devices [3-9]. 

Poly (thiophene)s are of particular interest as electfochromic materials owing to their chemical stability, ease of synthesis and processability. For the most part, current research has been focused on composites, blends and copolymer formations of several conjugated polyheterocyclics, polythiophene and its derivatives, especially PEIX)T. In one example, poly(3,4-ethylenedioxythiophene) (PEDOT)/poly(2-acrylamido-2-methyl-l-propanesulfonate) (PAMPS) composite films were prepared by Sonmez et al. for alternative electrochromic applications [50]. Thin composite films comprised of PEDOT/PAMPS were reported to switch rapidly between oxidized and neufial states, in less than 0.4 s, with an initial optical contrast of 76% at A.max. 615 nm. Nanostructured blends of electrochromic polymers such as polypyrrole and poly(3,4-ethylenedioxythiophene) were developed via self-assembly by Inganas etal. for application as an electrochromic window [26]. Uniir etal. developed a graft-type electrochromic copolymer of polythiophene and polytetrahydrofuran for use in elecfiochromic devices [51]. Two EDOT-based copolymers, poly[(3,4-ethylenedioxythiophene)-aZ/-(2,5-dioctyloxyphenylene)] and poly[(3,4-ethylenedioxythiophene)-aft-(9,9 -dioctylfluorene)] were developed by Aubert et al. as other candidates for electrochromic device development [52],... 

Polythiophenes with P-alkyl substituents including more than three carbon atoms are commonly soluble in organic solvents. Recently, electrochromic polymers such as poly(thiophene-3-acetic acid) and its copolymer with polythiophene were prepared. The electrochromic properties of these materials were studied by observing a color change from red to black during the potential sweep with a stability for 264 cycles, establishing a high electrochromic efficiency of up to 242 cm C at 750 nm [65],... 

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