By Topic

Full control of nematic pretilt angle using spatially homogeneous mixtures of two polyimide alignment materials

Sign In

Cookies must be enabled to login.After enabling cookies , please use refresh or reload or ctrl+f5 on the browser for the login options.

The purchase and pricing options are temporarily unavailable. Please try again later.
4 Author(s)
Lee, Ji-Hoon ; Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106, USA ; Kang, Daeseung ; Clarke, Christopher M. ; Rosenblatt, Charles

Your organization might have access to this article on the publisher's site. To check, click on this link: 

Two substrates were coated with a mixture containing two polyamic acids. One of the polyamic acids has an alkyl side chain and ordinarily is used for vertical liquid crystal alignment. The other polyamic acid does not have a side chain and ordinarily is used for planar liquid crystal alignment. The substrates were baked in order to promote imidization. It was observed that over a wide concentration range of mixtures the two polymer species comprising the alignment layer do not phase separate. A cell then was constructed and filled with the liquid crystal pentylcyanobiphenyl. It was found that the nematic pretilt angle θ0 is a function of the relative polymer concentration and can be controlled over the range from near 0° to ∼70° with respect to the vertical orientation. A model is proposed in which quartic terms in the surface energy are responsible for the variation of θ0 with concentration.

Published in:

Journal of Applied Physics  (Volume:105 ,  Issue: 2 )