A DEUTERON NMR-STUDY ON ORDER AND PHASE-BEHAVIOR OF LIQUID-CRYSTALLINE COPOLYMERS

Liquid-crystalline (LC) block copolymers of lamellar morphology were p repared via anionic polymerization of polystyrene-block-1,2-polybutadi ene and subsequent introduction of a deuterated mesogen by polymer ana logous reaction. Deuteron NMR measurements show that the first-order n ematic/isotropic transition in the block copolymer is changed to a cri tical behaviour under the influence of shear. In the nematic phase the order parameter is reduced with respect to the homopolymer, and there is no evidence of an isotropic boundary layer of the LC-block at the nematic/isotropic interface.