Molecular orientation gradients in thermotropic liquid crystalline fiber

The degree of molecular alignment averaged over mesolength scale areas within thermotropic liquid crystalline polymer (LCP) fibers has been intensely studied over recent years. In this work, the degree of molecular orientation is found from spatially-resolved electron diffraction of areas as small as 100 nm in diameter to relieve structural averaging of lower resolution techniques. This investigation reveals that the maximum degree of molecular alignment across a fiber 18 μm in diameter is approximately 1 μm from the fiber surface. Dark-field imaging shows region with little crystallinity adjacent to the fiber surface. The banded structure, typical of TLCP fibers, is also less apparent in the surface region.