Hydrodynamic, optical and conformational properties of molecules of aromatic polyesters containing 3,3′-biphenylene fragments in the main chains

The hydrodynamic, optical and conformational properties of molecules of fractions of two aromatic polyesters (APE) containing 3,3′-biphenylene fragments in their chains have been investigated by sedimentation-diffusion analysis and flow birefringence in dilute solutions. The experimental data on the translational mobility and dynamo-optical characteristics of molecules of these polymers are compared with those for previously investigated APE with similar structures but containing no biphenylene fragments. As a result of this analysis, the geometric parameters of the repeating chain unit were characterized, and the equilibrium rigidities of the molecule of the APE were estimated. It was shown that the flexibility of these molecules is determined by the character of intramolecular rotation about the biphenylene bond and that this rotation is virtually unhindered.