Isotropic-to-nematic transition in liquid-crystalline heteropolymers: II. Side-chainliquid-crystalline polymers

Abstract

We apply a density functional approach for arbitrary branched liquid-crystalline (LC)heteropolymers consisting of elongated rigid rods coupled through elastic joints developedin a companion paper (Wessels and Mulder 2006 J. Phys. Condens. Matter. 18 9335) to amodel for side-chain liquid-crystalline polymers. In this model mesogenic units are coupledthrough finite-length spacers to a linear backbone polymer. The stereochemical constraintsimposed at the connection between spacer and backbone are explicitly modelled. Using abifurcation analysis, analytical results are obtained for the spinodal density of the I–Ntransition and the variation of the degree of ordering over the various molecular parts atthe instability as a function of the model parameters. We also determine the location of thecrossover between oblate and prolate backbone conformations in the nematic phase.