Synthesis and properties of regioregular polyethers and polyesters with (eta(4)-cyclobutadiene)cobalt moieties in the main chain

Regioregular organocobalt polyethers (3 and 3) and polyesters (5-8) have be en prepared by the polycondensation of regioisomerically pure (eta(4)-tetra arylcyclobutadiene)cobalt-containing bis-phenols (9 and 10) with aliphatic or aromatic comonomers. The diols (9) offered rigid-rod p-terphenyl-like st ructural units, while their isomers (10) led to 90 degrees kinks in polymer ic backbones. The polymers (3, 5 and 7 = 'odd' series) were derived from th e bis-phenols (9), while their isomers (4, 6 and 8 = 'even' series) resulte d from 10. Most of the polymers (3-8) exhibited good solubilities in common organic solvents. In the case of the isomeric polyesters with aromatic bac kbones (7 and 8), the latter were more soluble, indicative of their higher configuration entropies. Glass transition temperatures of the 'odd' and 'ev en' isomers were similar, irrelative to the kinks in their backbones, but t hey showed good correlation with aliphatic-to-aromatic mass ratios and rigi dities of the main chains. The polymers of the 'odd' series exhibited cryst alline and liquid crystalline (polyesters, 7) phases, while their 'even' is omers remained amorphous. Correlations between mesomorphic properties and t he structure of the repeating units have been discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.