Dynamics and phase behavior of a supermacromolecular suspension under a magnetic field studied by time-resolved x-ray scattering

Dynamics and phase behavior of biological supermacromolecular (tobacco-mosaic virus) suspensions under magnetic field were investigated using a synchrotron-radiation time-resolved x-ray-scattering method. By increasing the molecular concentration, a nematic-to-smectic phase transition appeared and a transverse correlation within layers became evident at the highest concentration. A phase diagram depending on both magnetic-field strength and molecular concentration was presented. A dependence of the orientational relaxation time on magnetic-field strength in a nematic phase was also measured, which is explained as a magnetically induced collective rotational motion of the constituents within the nematic liquid crystal microdomains with an identical rotational correlation length. The application of magnetic field to a nematic phase suspension enhanced an evident nearest-neighbor correlation in short range which is different from a transverse ordering within layers in a smectic phase, suggesting a mesophase with a partially ordered radial density fluctuations. In a contrast, the application of a magnetic field in the smectic phase did not affect the macromolecular arrangement.