Fast switching films of nematic side chain copolymers
Liquid-crystalline side chain polymers may open interesting application possibilities in the area of display and optical data storage if the response times of these materials can be made sufficiently fast. Thin, well aligned films of nematic homopolymers and copolymers, containing covalently bonded dyes, have been prepared and the optical switching times for the Freedericksz deformation depending on relevant polymer material and cell properties have been measured. It turns out that the switching times can be essentially shortened by raising the clearing temperature T sub IN. This is due to the exponential dependence of the rotational viscosity y sub 1 from the absolute temperature. We succeeded in lowering the switching time by nearly three orders of magnitude only by enhancement of T sub IN by 50 degree C, achieving the fast response of 2 ms with a nematic polymer.