Steady-state shear experiments on a side-chain liquid-crystal polymer: Determination of the polymer conformation and liquid-crystal structure

We consider the effect of shear on the structure and the conformation of the main chain of a side-chain liquid-crystal polymer. The liquid-crystalline polymer is sheared using a cone and plate device, and the effect of this shear is determined in situ by small angle neutron scattering. We find that, in the isotropic and the nematic phases, the main-chain extensions in the shear plane are invariant within the shear range studied. In the smectic phase, however, the main-chain is elongated in the direction of the shear flow. This elongation is superposed to a confinement of these main chains between the mesogen layers. The mesogen layers exist in a well oriented mesophase parallel to the shear plane.