Лако-красочные материалы — производство

Electrochromic dyes, as the name implies, are dyes which undergo a colour change as a result of the application of electrical energy. These dyes are of obvious interest because of their potential for application in displays. One approach to the production of electrochromic displays involves the chemistry illustrated in Scheme 10.5. This approach makes use of colourless biscationic materials, such as the paraquat derivatives 249. As illustrated in the scheme, these compounds are reduced elec­trochemically to a coloured radical cation 250, which is deposited at an electrode. One of the principal difficulties which remains to be overcome commercially for displays using this chemistry is the ageing process which causes the deposited material, eventually, to crystallise, thus inhibiting the reverse oxidation process.

Scheme 10.5 The reversible electrochromism of paraquat derivatives

An alternative approach to the production of electroluminescent dis­plays has emerged from the discovery that poly(p-phenylenevinylene) (PPV), 251, produces a greenish glow when a thin film of the polymer is subjected to a high voltage. Since this discovery, a large number of light emitting polymers, mostly based on highly conjugated materials of the PPV type, have been prepared and investigated in the search for poly­mers with improved electroluminescence efficiency and which emit at a range of different wavelengths. There is no doubt that this research paves the way for significant future developments in flat-screen display technol­ogy.