This proposal combines experimental and theoretical investigations of the response of PDLC films to applied fields. The primary objective of this work is to obtain a comprehensive understanding of the major contributions to the switching mechanisms in these materials. This will enable systematic modification and control of the film characteristics to achieve optimum film performance for specific device applications. Experimental studies will include dielectric and transmission measurements of PDLC films in response to fields of sufficient strength to reorient the liquid crystal director. Electron microscopy will provide information on droplet geometry. These measurements will be used to correlate the response with important film properties: the electrical characteristics, liquid crystal elastic constants, droplet size and droplet shape. To achieve a comprehensive picture, the experimental investigations will be supplemented by theoretical studies of the response. In particular, the electric field in a birefringent (bipolar) ellipsoidal droplet will be examined in detail numerically. This will be coupled with calculations of the director configuration in the droplets to understand the role of the field strength, elastic constants and droplet geometry on the director realignment in a droplet. These calculations will be applied to recently developed models of the dielectric response and optical transmission for comparison with experimental response curves.
