Polymers with terminally cyanobiphenyl-substituted side chains

Summary Two acrylate side chain polymers in which the mesogenic moiety is a 4-cyano-biphenyl-4-yl group have been synthesized and characterized by d.s.c., optical microscopy and X-ray diffraction. If the mesogenic moiety is linked to the polymer backbone by a -O-CO-(CH₂)-₅ group, the resultant polymer is nematic. For a -O-(CH₂)-₆ group, the unusual NS_AN_re sequence is observed. X-ray diffraction has shown that the S_A phase has a partially bilayer structure : the molecules are arranged in an antiparallel, overlapping interdigitated structure with a layer spacing of about 1.4 times the length of the side chains. Monolayer fluctuations are also observed in this S_A phase.