Striped pattern formation in polymer dispersed liquid crystal films

Abstract

Composite films of polymer and liquid crystal (LC) have been prepared by a simple solution casting technique. The films obtained exhibit a polymer dispersed liquid crystal structure where LC droplets are dispersed in the polymer matrix. Casting the mixture of polymer solution and LC on a tilted substrate results in a specific texture in which arrays of LC droplets align parallel to each other, i.e. a striped pattern can be formed. The size of the droplets and the spacing between the lines are dependent on the substrate tilt angle and the preparation temperature. By using a dip-coating technique, a similar striped texture appears at a fast dipping velocity. From in situ observation of the stripe development, it is seen that the translation of the phase-separating region, accompanying the flow, plays a more important role in the formation of the striped patterns than the flow of the solution itself.