화학공학소재연구정보센터
Langmuir, Vol.11, No.12, 4838-4843, 1995
Chiral Director Field in the Nematic Liquid-Crystal Phase Induced by a Poly(Gamma-Benzyl Glutamate) Chemical-Reaction Alignment Film
Poly(gamma-benzyl glutamate) (PEG) 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(gamma-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 alpha-helical structure of PEG 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 were responsive at voltage frequencies in the MHz region, we conclude from our investigations by time-resolved infrared spectroscopy that the PEG 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 PEG molecules and the interfacial liquid crystal molecules.