Soluble aromatic polyesters derived from 2′,5′-dialkoxy-p-terphenyl-4,4′-diols or 2′′,5′′didodecyloxy-p-quinquephenyl-4,4′′′′-diol and terephthaloyl or 2,5-dialkoxy-terephthaloyl dichlorides were prepared. The polymers were characterized by viscosimetry, thermal analysis, and X-ray diffraction. The polyesters show two or more endothermic transitions. The high-temperature transitions to an isotropic melt moved to lower temperatures as the side chain length increased. Structural information was obtained from the temperature-dependent X-ray data. Various structures were observed depending on the type of the phenylene segment in the backbone, the length of alkoxy side chains, and the number of side chains per backbone repeat unit.

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A series of rigid aromatic polyesters containiig substituted oligophenyls wasprepared. Aliphatic and aromatic side groups were used to increase the solubility. New oligophenyldiols were synthesized by coupling aromatic Grignard reagenta with aromatic halides, using palladium complexes as catalysta. The polyesters were prepared by melt polycondensation and characterized by viscosimetry, thermal analysis, and dynamic mechanical analysis. The temperature dependence of the intrinsic viscosity, in the range 30-85 O C , was sensitive to the type and position of the side groups. Polyesters with aromatic substituents were stable up to 400 "C. The glass transition temperatures of the polyesters with aromatic side groups were in the range 150-250 "C. Dynamic mechanical analysis showed that in the cases where aromatic Substituents were used to increase solubility, the obtained polymers appear to have useful mechanical properties at high temperatures. The glass transitions appeared in the range 160-220 "C, while a plateau modulus in the range of 108 Pa was obtained at high temperatures (up to 350 O C ) .

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