Large Scale Textures in Nematic Polyethers: 2. New Aspects of Orientational Order and Structure Hierarchy

Abstract

The flow-induced large-scale textures arising in thermotropic nematic polymers presented in Part I of this study have been further explored. Optical and scanning electron microscopy and light diffraction are employed to interpret the nature of these textures. It was found that on a large-scale, molecular arrangement similar to vector fields around disclinations in ordinary nematics, is created due to superposition of radial flow fields. On a fine scale, there are several stages of relaxation of the internal nematic substructure from the highly oriented state; first, a banding appears due to periodic variations of the local director along the long-range orientation, subsequently relaxing gradually to a polydomain texture. It is shown that interaction of these two processes on the long and fine scales is responsible for the range of complex textures. Once recognized for what they are, these textures can be interpreted without misconceptions, which may otherwise arise due to actual simplification of the polarizing optical analysis.

Key Words:

• nematic polyethers
• optical textures
• scanning electron microscopy
• polarizing optical analysis