Molecular structure in the crystalline phase of a segmented liquid crystalline polyester

Molecular structure refinement of a liquid crystalline segmented polymer us ing X-ray diffraction methods is reported. The investigated polymer contain s the 3-allylbiphenyl unit as nematogenic unit. The space group is P2(1)/a, with cell parameters a = 12.82 Angstrom, b = 8.44 Angstrom, c = 19.72 Angs trom, and beta = 153.2 degrees, with two chains per unit cell. The main fea ture of this molecular packing is the layered organization of chains with a transversal intercalation of the flexible and the rigid units in the layer . Repetition of layers in space leads to an herringbone packing of biphenyl units along [001]. Transversal register between chains is such that the tw o phenyl rings of biphenyl unit are involved in "edge to face" contact.