Continuous control of liquid crystal pretilt angle from homeotropic to planar

A mixture of two polyamic acids, one having an alkyl side chain and ordinarily used for vertical liquid crystal alignment, and the other without a side chanin and ordinarily used for planar alignment, is deposited on two substrates and baked at high temperatures. When the resulting cell is filled with the liquid crystal pentyl cyanobiphenyl, it is found that the pretilt angle θ0 is a function of the baking temperature, and can be controlled continuously over the range 0◦ ≤ θ0 . 90◦. a. Present address: 3M Company, St. Paul, MN b. Permanent address: Dept. of Electrical Engineering, Soongsil University, Seoul, Korea