Rotational Viscosities of Polymer Solutions in a Low Molecular Weight NematicLiquid Crystal

摘要

The behavior of dilute solutions of flexible polymer chains in a nematic solventhave been studied by different physical methods: neutron scattering, NMR and viscosity measurements. We are primarily concerned with the rotational viscosity gamma which characterizes the friction connected with the rotation of the director field, n, while the liquid is at rest. In many practical applications, it is necessary to gamma to suit a particular situation, for instance; reducing the switching time in liquid crystal displays, or in controlling the drawing of high-strength fibers from liquid crystalline polymer solutions. In the latter case, gamma is a major factor in determining the relaxation of the director field after the fluid leaves the spinneret. Furthermore, the time scale for the development of periodic or banded textures in polymeric nematics, subjected to flow or magnetic fields, is essentially set by the magnitude of gamma.