Electro-chromic property

We all had jobs to do and were enthusiastic. Other members of Coraor s group, who were involved in other research areas also contributed to our program, especially Dr. S. V. R. Mastrangelo, who became interested in the electro-chromic properties of our leuco dyes. 

Bithiophene can be simultaneously electro-chemically oxidized and polymerized to yield conducting films of composition [C I iKClO Q.iglx. The conductivity of the polymer varies from 0.04-1.0 (flcm)-1 depending on polymerization conditions. The polymer has interesting electro-chromic properties. Switching speeds of 500 ms are obtainable for an electrode of area 2.4 cm2. 

Danieli et al. [36] prepared a copolymer of thiophene and benzene by electrochemically homopolymerizing 1,4-di-(2-thienyl)benzene and, according to Mitsuhara and Tanaka [37], its films exhibit multicolor electro-chromic properties. 

A novel type of device configuration first apparently proposed by Inganas and Lundstrom [865], and developed to a considerable degree of refinement by Chandrasekhar et al. [866], is one which is based on interfacing a CP to an inorganic semiconductor (SC). This utilizes the well known electrochromic properties of the CP. The SC may be a material such as CdS or Ai-Si. In this context, it should be noted that the CP, in its doped form, is also a SC, but its semiconducting properties are not the primary focus of interest in such SC/CP interfaces- rather, its electro-chromic properties are. 

Applications of titania nanotube arrays have been focused up to now on (i) photoelectrochemical and water photolysis properties, (ii) dye-sensitized solar cells, (iii) photocatalysis, (iv) hydrogen sensing, self-cleaning sensors, and biosensors, (v) materials for photo- and/or electro-chromic effects, and (vi) materials for fabrication of Li-batteries and advanced membranes and/or electrodes for fuel cells. A large part of recent developments in these areas have been discussed in recent reviews.We focus here on the use of these materials as catalysts, even though results are still limited, apart from the use as photocatalysts for which more results are available. 

Chromic properties (- electrochromism, electro-chemically induced chemiluminescence). 

Titanium(II) oxide is manufactured by heating Ti02 and Ti in vacuo. It is a black solid and a metallic conductor which adopts an NaCl lattice with one-sixth of both anion and cation sites unoccupied. The oxide is a non-stoichio-metric compound with a composition typically in the range TiOo.82-TiOi 23. A commercial use of TiO is in electro-chromic systems (see Box 22.4). Conducting properties of the first row metal(II) oxides are compared in Section 27.3. 

Electrochromism is the reversible change in optical properties of a material caused by redox reactions. The redox reactions can be initiated when the material is placed on the surface of an electrode. When the electro-chromic material is capable of showing several colors, it is addressed as polyelectrochromic. 

Composites of conducting polymers, e.g., polyaniline and PEDOT, with polyacids, e.g., poly (2-acrylamido-2-methyl-l-methyl-l-propanosulfonic add) (PAMPS), have been shown to be electro-chromic. The polyadd acts as a dopant for the polymer film with the optical properties of the composite being contributed by the conducting polymer. The composites are formed by dther chemical or electrochemical polymerization of the electrochromic component monomer in the presence of the polyacid. Films of polyaniline-PAMPS switch from yellow to green and finally to blue on oxidation [228,229]. Composite films of PEDOT and PAMPS show similar electrochromic properties to PEDOT with the films switching from dark blue in the neutral state to Kght sky blue in the oxidized state [140,230,231]. 

In spite of the large number of recent papers and reviews describing the synthesis, spectroelectrochemical properties and applications of electro-chromic materials or fluorescent conjugated polymers, there are just a few reports in the literature that describe the preparation, characterisation and... 

Proton-conducting GPE suitable for ECD applications were prepared by the co-polymerisation AMPS and ethylene glycol methacrylate phosphate (EGMP) either with MMA, GMA or 2-hydroxyl ethyl methacrylate (HEMA) in polar aprotic solvents, such as PC, EC or DMF. Use of the copolymers instead of polyAMPSA allowed the preparation electrolytes with various polymer matrix contents and various concentration of AMPS or EGMP. Gels swollen with solvent mixtures containing more than 40 wt% PC were completely amorphous. This property is important for the electro-chromic applications serious crystallization problems which severely decrease ionic conductivity are avoided. 

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