Synergistic ordering of side-group liquid crystal polymer and small molecule liquid crystal: Order and phase Behavior of nematic polymer solutions

摘要

Addition of a small-molecule liquid crystal (5CB) to a cyanobiphenyl-based side-group liquid crystal polymer (SGLCP) stabilizes nematic order, increasing the isotropization temperature (T-NI) more than 15 degrees C. Despite synergistic ordering at high concentration, small amounts of polymer destabilize nematic order. Even though T-NI(SGLCP) is 27 degrees C greater than T-NI(5CB), H-2 NMR shows that the order parameter of the SGLCP is less than that of 5CB at concentrations for which monodomains were accessible (<= 10 wt,-%). The results imply that nematic order is frustrated in the bulk polymer and addition of small LC relaxes this fustration by allowing greater configurational freedom. Conversely, adding small amounts of polymer to the bulk 5CB introduces frustration, resulting in the strong asymmetry of the phase diagram.