SANS Study of a Semiflexible Main Chain Liquid Crystalline Polyether

A main-chain semiflexible polyether (TPB-10) has been studied in the nematic phase by small angle neutron scattering (SANS) and by neutron and X-ray diffraction. Principally, we have determined the polymer chain conformation by SANS for mixtures of deuterated and hydrogenous polymers, aligned using a strong magnetic field (4.2 T). In good agreement with previously reported results on nematic polyesters, our data are well fitted to a model of a cylinder in which the main chain forms one hairpin defect including two very confined and extended wires. Moreover, the X-ray diffraction patterns show that smectic C fluctuations occur in the low-temperature nematic range. Referring to the layer normal of the local SC arrangement, the mesogens are tilted with respect to the field. Strikingly, the whole chains are also tilted with the same angle as the mesogenic units. © 1995, American Chemical Society. All rights reserved.