Optical quality, polymer film

On the other hand, solution spectra are difficult to record at very low temperatures, due to the difficulty of having glasses of optical quality. Polymer films have been used in some cases to overcome these problems. 

Optical quality polymer film preparation. The H, CN, NO2, and CH3O substituted azophenol polymers were soluble in most polar organic solvents. 

Optical quality thin films of metallic polymers are useful, therefore, as transparent electrodes [68]. For example, polyaniline [69], polypyrrole [70] and PEDOT [71] have been used as transparent hole-injecting electrodes in polymer LEDs (the initial demonstration of mechanically flexible polymer LEDs utilized PANl as the anode [69]). Transparent conducting films can be used for a variety of purposes for example, as antistatic coatings on CRT screens, as electrodes in liquid crystal display cells, or for fabricating electrochromic windows. 

In last years one observes a fast progress in synthesis and elaboration of non-centrosymmetric functionalized polymers for applications primarily in electrooptic modulation and frequency conversion. These materials possess large second order nonlinear optical susceptibility x and can be easily processed into good optical quality thin films for travelling wave applications. Essentially four types of polymeric structures have been developed, as shown in Fig. 1 ... 

Good optical quality thin films of PAV have been prepared through a new precursor polymer that is soluble in organic solvents [16]. For example, PTV thin film can be fabricated as follows. Polymerisation of a sulfonium monomer, 2,5-thienylene bis(methylene-dimethyl-sulfonium chloride), is carried out in a methanol-water mixture... 

This enzymatically synthesized azophenol polymer has an extremely high dye content (nearly 100%) and is soluble in most polar organic solvents. It forms good optical quality thin films. Polymer solutions show reversible trans to cis photoisomerizations of the azobenzene groups with long relaxation time. The poly(azophenol) films also exhibit photoinduced absorption dichroism and large photoinduced birefringence with unusual relaxation behavior. 

In Figure 8-1 we show the chemical structure of m-LPPP. The increase in conjugation and the reduction of geometrical defects was the main motivation to incorporate a poly(/ -phenylene)(PPP) backbone into a ladder polymer structure [21]. Due to the side groups attached to the PPP main chain excellent solubility in nonpolar solvents is achieved. This is the prerequisite for producing polymer films of high optical quality. A detailed presentation of the synthesis, sample preparation,... 

The important item is that this coating can be applied at room temperature and cured at 90 °C and gives a clear film with optical quality. Typical properties of inorganic polymers (hardness) and organic polymers (coating as a lacquer and low temperature processing) could be combined in one and the same polymer. 

Polyarylenevinylene (PAV) expressed by the chemical formula of [-Ar-CH=CH-]n, where Ar is an arylene ring, is an attractive n-conjugated polymer family because of the following features (i) by the thermal conversion from polyelectrolyte or organic-solvent-soluble precursors, one can obtain the PAV films which have large third-order susceptibility and excellent optical quality, and (ii) the band gap can be adjusted by suitable selection of the arylene rings. 

Three kinds of PAV films was prepared using methoxy pendant precursors. The chemical structures and synthetic route of the PAV films used in this study are shown in Fig. 19. The details of synthesis of the methoxy pendant precursors have been described in refs. 29 and 30. The precursors were soluble in conventional organic solvents, for example, chloroform, dichloromethane, benzene and so on. The precursor polymer thin films were spin-coated on fused quartz substrates from the chloroform solutions. The precursor films were converted to PAV films by the heat-treatment at 250 0 under a nitrogen flow with a slight amount of HC1 as a catalyst. This method provided high performance PAV films with excellent optical quality. 

Indeed these qualities have been developed since the mid-Century so that in a particular segment of the information industry such as telephones and communications, our volume of synthetic polymers used annually exceeds that of any other class of materials, although the actual tonnage of metallic and inorganic matter still leads. For the world of tomorrow, we find microelectronics, thin film circuitry and systems and, especially now photonics, with lasers and light guides, to be dominant components. All of these strongly use polymers, for their special physical-chemical as well as familiar mechanical and electro-optical qualities. 

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