Fused state/sup 13/C-NMR study on liquid crystalline polyacutylene derivatives - magnetically forced alignment and orientational behavior

Summary form only given. Magnetically forced alignments and orientational behaviors of a series of side-chain liquid crystalline polymers, poly(mono-substituted acetylenes), as well as a liquid crystalline mononux, have been investigated through the fused-state/sup 13/C NMR measurements with proton dipolar decoupling. Upon a phase transition from isotropic to nematic or smectic phase, aromatic carbon signals notably shifted to the lower magnetic field, whereas aliphatic carbon signals slightly shifted to the higher magnetic field. This indicates that in the nematic or smectic phase, the side chain liquid crystal group is preferentially aligned along the direction of magnetic field. Analyses of chemical shift tensors are also carried out to evaluate an order parameter and shieldbig anisotropy in liquid crystalline phase, As a result, we have demonstrated that the liquid crystalline conjugated polymers are uniaxially aligned due to the magnetically forced alignment of the liquid crystalline side-chain, giving rise to a mono-domain structure.