STATISTICAL THERMODYNAMICS OF POLYMER LIQUID-CRYSTALS - VARIATION OF CONCENTRATION OF THE MESOGENIC COMPONENT

Polymer liquid crystal (PLC) macromolecules consisting of LC and flexible sequences with varying composition theta of LC segments are considered using the lattice approach of Flory,5,6 with the orientational distribution function developed by Flory and Ronca.8,9 We obtain a partition function dependent on THETA, on the average length of rigid sequence etaBAR, on the order parameter s, and on temperature T. For THETA = 1 the equations reduce to the case of fully rigid rods treated before by Flory and collaborators. A drastic change in the slope of s vs etaBAR curve is observed around THETA = 0.2, indicating a large increase in the chain alignment. A prediction of T(LC-i) in function of theta for a given etaBAR value is shown. LC-rich phase are formed for THETA > THETA(LC limit); that limit is discussed in relation to earlier work by Flory and Matheson, experimental evidence, and the present results.