Accession Number : ADA296841

Title :   Investigations on Langmuir-Blodgett Films as Alignment Layers for Liquid Crystals,

Corporate Author : KENT STATE UNIV OH DEPT OF PHYSICS

Personal Author(s) : Chen, Jianmin ; Vithana, Hemasiri ; Johnson, David ; Albarici, Aparecido ; Lando, Jerome

PDF Url : ADA296841

Report Date : 1994

Pagination or Media Count : 35

Abstract : Multilayer polyimide(PI) films were successfully fabricated using the Langmuir-Blodgett(LB) technique. These films were studied in several ways relevant to their use as liquid crystal alignment layers. (1) The influence of dipping speed and creep time on the orientational order of PI-LB films was investigated by means of birefringence measurements. (2) For comparison, we measured the pretilt angles and polar anchoring strengths of liquid crystal(LC) cells assembled with PI-LB films and rubbed PI-LB films as alignment layers. (3)The anchoring direction of the liquid crystal was found to be solely determined by the dipping direction of uppermost PI-LB layer, regardless of the dipping direction of deeper layers. (4) Combining results of the above studies with measurements of pretransitional birefringence(above the isotropic to nematic(I-->N) transition) and observations of the growth of the alignment texture just below the nematic-isotropic transition, we draw the conclusion that the range of interaction between the PI-LB film and LC molecules is quite short(approx. 4.5A) and that the alignment mechanism is epitaxial. jg p.3

Descriptors :   *FILMS, *ALIGNMENT, *LIQUID CRYSTALS, *POLYIMIDE PLASTICS, VELOCITY, INTERACTIONS, LAYERS, MOLECULES, EPITAXIAL GROWTH, TIME, STRENGTH(GENERAL), CREEP, BIREFRINGENCE, TEXTURE.

Subject Categories : Polymer Chemistry
      Physical Chemistry
      Plastics
      Crystallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE