Electrochromic polymers characteristics

Electrolytic oxidation of acetonitrile solutions of monomer mixtures of dithioenopyrrole 23 and dithienothiophene 15a using tetrabutylammonium perchlorate as an electrolyte can produce poly(dithienopyrrole-dithienothiophene) copolymer which shows good electrochromic <1994EAC2159> characteristics. Similarly, films of poly(dithienopyrrole-thionapthene indole) and poly(dithienopyrrole-thionapthene indole) co-polymers can be obtained from DTT and DTP with thionapthene indole 85 (TNI) <1996SM(82)11>. 

In a more recent approach, polyelectrolyte multilayers of poly(butanyl viologen) dibromide (PBV) and poly(styrene sulfonate) sodium salt (PSS) have been prepared (52) using an alternating polyion solution deposition technique. In this technique, the ITO substrate is alternatively exposed to positive and negative polyelectrolytes, with spontaneous polymer deposition via coulombic interactions between surface and polyion of opposite charge. In this layer-by-layer deposition technique, all redox material is electrochemically addressable, with good electrochromic performance characteristics. 

Cells with two electrochromic polymers with complementary dyeing characteristics, dual polymer cells, like cells in which FEDOTFSS was combined with polypyrrole gained significant attraction as early as 1997 since besides flexibility they offer potentially high optical contrasts (>50% transparency) as well as multicolor capabilities and gave rise to an optimistic view of the future of such systems. ... 

The conformational mobility of a chromophoric main-chain polymer is often connected to its electronic structure. Therefore, changes in the UV-visible absorption spectra and/or chiroptical properties are spectroscopically observable as thermo-, solvato-, piezo-, or electrochromisms. It is widely reported that o-conjugating polysilanes exhibit these phenomena remarkably clearly.34 However, their structural origins were controversial until recently, since limited information was available on the correlation between the conformational properties of the main chain, electronic state, and (chir)optical characteristics. In 1996, we reported that in various polysilanes in tetrahydrofuran (THF) at 30°C, the main-chain peak intensity per silicon repeat unit, e (Si repeat unit)-1 dm3 cm-1, increases exponentially as the viscosity index, a, increases.41 Although conventional viscometric measurements often requires a wide range of low-dispersity molecular-weight polymer samples, a size exclusion chromatography (SEC) machine equipped with a viscometric detector can afford... 

However, ultra-thin films of unsubstituted polyaniline deposited on ITO glass electrode produced by dip coating, spin coating and the LB technique showed the most informative voltammetric characteristics. The single-layer LB films of polymer showed much better and reversible electrochromic activity on repeated scanning within up to 0,9 V in 1,0 M HCl solution than in electrochemically prepared materials [287],... 

PEDOT, one of the most popular jr-conjugated polymers, has been intensively studied for developing nanoscale materials as well as for application to various nanodevices such as biosensors and electrochromic devices, and for drug delivery [82-84]. However, studies on PEDOT nanomaterials and bulk films have mainly focused on their electrical and structural properties and on the various applications of the conducting form of the material (i.e., doped PEDOT systems). The light-emitting characteristics of doped and de-doped PEDOT nanomaterials were first reported by Park et al. in 2008 [43]. 

The poly(amine-hydrazide)s can be prepared from the polycondensation of 9-[MA -di(4-carboxyphenyl)amino]anthracene with terephthalic dihydrazide and isophthaUc dihydrazide by the Yamazaki phosphorylation reaction. The poly(amine-hydrazide)s are readily soluble in many common organic solvents and can he solution cast into transparent films [48]. The materials can be thermally cyclodehydrated into the corresponding oxadiazole polymers in the range of 300-400 °C. An anthrylamine-based poly(amine-1,3,4-oxadiazole)s shows electrochromic characteristics with changing color from the pale yellow neutral form to the red in the range of 0.00 to -2.20 V. 

TABLE 7 Characteristics of Electrochromic Cells Made from Conducting Polymers... 

An early reported example of an electrochromic conducting polymer is polypyrrole (56), which in the imdoped (reduced) insulating state is yellow/green, with a peak maximum characteristic of a jt-jt interband transition. The interband transition energy decreases upon doping to yield the blue/violet doped (oxidized) conductive state (Fig. 7). 

Subsequent to isolation of the polymer, the metallization could be conducted in a similar manner as that of the complexes reported elsewhere for DCH-Ru complexes (27-28). The ruthenium complex polymers, shown in Figure 2, thus made would be expected to exhibit similar electrochromic properties as the dinuclear ruthenium complexes while possessing the film forming characteristics of the parent polymer. We report herein the synthesis and characterization of these polymers. 

Volume 7 summarizes new trends on liquid crystals, display, and laser materials. The topics include liquid crystals for electro-optic applications, switchable holographic polymer-dispersed liquid crystals, electrochromism and electrochromic materials for displays, materials for solid-state dye lasers, photophysical properties of laser orientational relaxation processes in luminescence, and lasing of dyes and photosensitive materials for holographic recording. 

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