[13] Flow birefringence

Publisher Summary Theoretical considerations indicate that if the solute macromolecules are geometrically and therefore optically asymmetric, the double refraction of the system appears as a result of the equilibrium between the orienting effect of the applied field and the disordering effect of the Brownian motion. The flow-birefringence apparatus is simple, and it can be easily constructed in the laboratory. The method of measurements is also simple. The measurement of the extinction angle in a certain range of the velocity gradient can give quantitative information on the size and shape of rigid solute particles by the determination of the rotary diffusion constant. In some cases, the change of the shape with environmental conditions can be detected by the extinction angle change. On the other hand, information on the optical anisotropy of solute particles obtained by flow birefringence is mostly qualitative. However, the theoretical foundation is not sufficient for quantitative analyses.