Polymeric materials electrochromic devices

Other materials being investigated include ferrocene with a bipyridinium salt,234 niobium oxide,235 nickel oxo-hydroxide,236 and cobalt oxohydroxide.237 The last is pale yellow in the reduced state and dark gray in the oxidized state. A typical electrolyte is lithium perchlorate in propylene carbonate. Solid electrolytes, such as a lithium salt (perchlorate, tetrafluoroborate, or triflate), in a polyepoxide238 or in a polyvinyl chloride gel in ethylene carbonate-propylene carbonate,239 lithium iodide in polyvinyl bu-tyral,240 and Naflon H (a polymeric perfluorocarbon-sulfonic acid),241 have also been tested. Some other systems use suspended particles between two panes of glass.242 When the particles are aligned by an electric field, the window becomes transparent. Combination photo-voltaic-electrochromic devices are under study.243... 

Fused azole systems with three heteroatoms can be represented by ben-zothiadiazole (BT), benzoselenodiazole (BSe), benzotriazole (BTA)." Among them the heterocycle BT is most widely used in conjugated co-polymers. Derivatives of BT have been widely used in organic electronic devices, especially in terms of electrochromic applications. While incorporated into the conjugated backbone these BT moieties bring to the polymeric material such properties as strong ICT transition dipole, multicolored electrochromism and efficient photoluminescence. 

Ethylenedioxythiophene (EDOT) (34) is now commercially available. Hey-wang and Jonas [234-236] first polymerized EDOT and found that the relevant polymer could be useful for antistatic coatings. Heinze and co-workers [237] subsequently studied the spectroscopic and electrochemical properties of poly(EDOT) the optical band gap of the polymer is about 16 eV (760-780 nm). Inganas and colleagues [238] showed the usefulness of poly(EDOT) as a potential material for electrochromic devices because of its ability to cycle between an opaque blue-black in the reduced (undoped) state and a transparent sky blue in the oxidized (doped) state. Recently, poly(EDOT) has been used for the construction of rapidly switching solid-state electrochromic devices based on complementary conducting polymer films [239]. 

Two active species such as a free radical and a hydrated electron generated during y-irradiation were used in preparing polymer nanocomposites. Various polymer-clay nanocomposites using y-ray polymerization of the desired monomers can be prepared in a one-step process at room temperature and ambient pressure. The polymer-clay nanocomposites have enhanced moduK, decreased thermal expansion coefficients, reduced gas permeabiUty and increased ionic conductivity. Precious metals have been studied most extensively among polymer-metal nanocomposites and used as catalysts in sensors, photochromic and electrochromic devices and recording materials. Various functional groups can be introduced on the CNT surface by y-irradiation polymerization as a one-step process. The polymer-CNT nanocomposites can be used as supports to immobilize biomolecules in biosensors. 

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