Structure and properties of aromatic poly(1,3,4-oxadiazole)s

Summary form only given. Aromatic poly(1,3,4-oxadiazole)s are known to have a combination of valuable properties, such as thermal and hydrolytic stability, strength, stiffness, fatigue resistance, and a relative low density. Also their electrical or optoelectrical properties and their electroluminescence behaviour are of practical interest. Therefore, a short review is given about recent results of electrochemical properties and their relation to the molecular as well as supramolecular structure of aromatic poly(1,3,4-oxadiazole)s. Like other heterocyclic polymers the film forming, rigid rod poly(p-phenylene-1,3.4 oxadiazole), (p-POD), exhibits small but distinct and perceptible electronic conduction. P-POD can easily be n-doped electrochemically and the resulting electronic structure supports a facile charge transport. The doping process as well as the diffusion of the counter-ions in thin polymer films determined by cyclic voltammetry and impedance spectroscopy are described in dependence on the chemical structure. p-POD forms two modifications, /spl alpha/- and /spl beta/-form, as can be evidend by IR-spectroscopy and by wide-angle X-ray scattering (WAXS). Whereas the /spl beta/-modification is less ordered the /spl alpha/-modification has a higher degree of order. The experimental conditions to realize the /spl alpha/-structure in a direct way are illustrated. Moreover, the relationship between the configuration of the macromolecular chain and the typ of modification is discussed.