Electro-thermal switchable bistable reverse mode polymer stabilized cholesteric texture light shutter

We studied the effects of different UV curing intensities and monomer concentrations on the distortion of polymer network of reverse mode polymer stabilized cholesteric texture (PSCT) after the application of a high voltage pulse perpendicular to the cell substrates. SEM observations indicated that lower intensities of UV irradiation resulted in the formation of more compact polymer networks with smaller voids. The majority of cholesteric liquid crystal was heavily affected by the distorted polymer network, meaning that the stabilized focal conic texture was unable to revert to the planar texture via the annealing treatment. Additionally, as the monomer concentrations increased, the resistance of the polymer network toward a high voltage pulse applied perpendicularly to the cell substrates increased, resulting in less pronounced distortion. With the use of a higher UV curing intensity and a lower monomer concentration, we created an optimized polymer network that could stabilize the scattering focal conic texture after distortion, and revert to the transparent planar texture via the annealing treatment, thereby giving rise to an electro-thermal switchable bistable reverse mode PSCT light shutter. It exhibited excellent gray scale performance, and the ability to maintain the bright and dark states without the need to apply an electric field, and thereby holds tremendous promise for use in energy efficient and thermally insulating switchable window. (C) 2011 Elsevier B.V. All rights reserved.