Internal orientations in externally deformed nematic polymer liquid crystals.

The system of linear polymer liquid crystal (PLC) macromolecules, each modeled by semiflexible chain of alternate connected flexible and stiff rodlike sequences, is externally deformed. As a result, two orientation phases for hard rods are generated. One of them is nematic N+ with orientation parameter s>0; this has the place in monomer liquid crystal (MLC) systems and in PLCs. The nematic N- phase with s>0 appears in deformed PLCs only. This causes the fact that orientation of PLC chains, as a whole, is generated also by the system deformation. A discussion of that effect is the main goal of this article. The change of orientation is also discussed dependent on changes of the system temperature and parameters of the chain structure, such as the liquid crystal component concentration, contour lengths of stiff and flexible parts, and internal interactions parameters. Average shape of PLC chain and the shape anisotropy are calculated and discussed.