Hydrodynamic, optical, and electrooptical properties of an aromatic polyester containing azobiphenyl fragments in the backbone

Translational and rotational friction, as well as optical and electrooptical properties, of aromatic polyester molecules bearing azobiphenyl fragments in the backbone were studied. The molecular masses of the tested fractions and the original polymer ranged from 6800 to 73000. The length of the Kuhn segment was found to be A = 24.4 x 10(-8) cm. Based on dynamic birefringence data, the optical anisotropy of the Kuhn segment alpha(1)-alpha(2) and the unit length of a macromolecule beta were measured to be 225 x 10(-25) cm(3) and 6.9 x 10(-17) cm(2), respectively. These values are typical of alkylenearomatic polyesters. It was substantiated that the model comprising two conformers (trans and cis) of biphenylene groups can be applied to the analysis of the conformational properties of polymers containing biphenylene fragments. In solutions of the polymer under consideration, the positive sign of the equilibrium electrical birefringence was discovered and ascribed to the existence of mesogenic nuclei of this polymer occurring in bent conformations.