EFFECTIVE MEDIUM THEORY OF POLYMER DISPERSED LIQUID CRYSTAL DROPLET SYSTEMS - II - PARTIALLY ORIENTED BIPOLAR DROPLETS

摘要

We construct a theory of the dielectric properties of a polymer dispersed liquid crystal droplet film containing bipolar droplets whose principal axes respond to an electric field. The theory involves a balance of an elastic energy term favouring an initial zero-field distribution of droplet axes and a dielectric energy term favouring droplet orientation parallel to an imposed field. We discuss (i) droplets initially orientationally ordered by an in-plane strain field and (ii) an initially random distribution of droplets. In case (i) we find a weakly droplet concentration dependent sharp threshold field at which droplet reorientation occurs. In case (ii) we find more gradual droplet reorientation. In the latter case the droplet axis distribution exhibits an unexpectedly rich structure. [References: 15]