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Control of Tilt Angle in the Nematic Liquid Crystal on the Homeotropic Polyimide Surface as a Function of the Baking Condition

소성 조건 변화에 따른 수직 폴리이미드 표면에서 이용한 네마틱 액정의 틸트 제어

  • 황정연 (연세대학교 전기전자공학과) ;
  • 이경준 (연세대학교 전기전자공학) ;
  • 김강우 (연세대학교 전기전자공학) ;
  • 서대식 (연세대학교 전기전자공학과)
  • Published : 2004.06.01

Abstract

The control of tilt angle for nematic liquid crystal (NLC) with negative and positive dielectric anisotropy on the rubbed homeotropic polyimide (PI) using baking method by hot plate equipment was investigated. LC tilt angle decreased with increasing baking temperature and time. Especially, the low LC tilt angle of positive type NLC (Δ$\varepsilon$>0) on the rubbed homeotropic PI surface by increasing temperature and time was measured. The tilt angle of positive type NLC(Δ$\varepsilon$>0) is smaller than that of the negative type (Δ$\varepsilon$>0) on rubbed PI with increasing baking temperature and time. We consider that the tilt angle of NLC is decreased due to increasing the steric interaction between horizon component of permittivity $\varepsilon$ = of NLC and the stress of polymer side chain by high temperature. As the increase of baking temperature, we obtain that AFM (atomic force microscope) image of rubbed PI surface using Hot-plate method has formed better solid micro-groove structure than oven method.

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