A Chiral Director Field in the Nematic Liquid Crystal Phase Induced by a Poly(.gamma.-benzyl glutamate) Chemical Reaction Alignment Film

Poly(y-benzyl glutamate) (PBG) bonded covalently to a flat substrate at a terminal position of the main chain and formed an aligned dipole layer because of its rigidity. The authors call this a poly(y-benzyl glutamate) chemical reaction alignment (PBG-CRA) film. Using the PBG-CRA film as an orienting film for nematic liquid crystals, liquid crystal molecules were oriented spirally to generate a novel chiral director field in the liquid crystal phase despite the absence of chirality in the liquid crystal molecule, the sense of which depended on that of the α-helical structure of PBG on the surface, resulting in the observation of a spiral texture. Since the liquid crystal molecules in the vicinity of the PBG-CRA film were able to respond more rapidly to an applied electric field than those for a rubbed polyimide film and werq responsive at voltage frequencies in the MHz region, we conclude from our investigations by time-resolved infrared spectroscopy that the PBG molecules are reversibly responsive to an external stimulation due to their rigidity and large dipole moments and that the dipole-dipole interaction takes place between the PBG molecules and the interfacial liquid crystal molecules.