Characterization of polymer dispersed liquid crystal systems

Polymer dispersed liquid crystal systems have received much attention because of their potential for display applications. The electro-optic properties of these films are dependent on the final morphology of the system which in turn is governed by the phase separation processes used to form these materials. In order to be cost effective, the amount of LC used in the PDLC films must be minimized, which requires the LC phase droplets be maximized. It is essential to understand the kinetics of phase separation to optimize the amount of LC used in these films.; An overview of the importance of PDLCs for display applications, ramifications of the technology and then the different phase separation techniques that affect the final structure is presented. The phase behavior of thermoplastic polymer-dispersed liquid crystal system is studied with particular emphasis on the various transitions that occur within the system. The extent of plasticization of the polymer(polymethyl methacrylate) by the low molecular weight liquid crystal(E7) along with the several transitions of the LC (Liquid Crystal) are determined by modulated DSC (Differential Scanning Calorimetry). Optical microscopy was used to construct the temperature versus composition phase diagram.; The phenomenon of coalescence and Ostwald ripening of the liquid crystal(E7) droplets dispersed in poly(n-butyl methacrylate) (PBMA) is studied. Infrared microspectroscopy is used to generate functional group images of the spatial compositional fluctuations that occur within the system as a function of time.; A novel experimental technique is introduced to conduct in situ diffusion and miscibility studies of PDLC systems. Quantitative phase diagrams are constructed for the PBMA and E7 mixture by the combination of IR microspectroscopy with the contact method.; In situ diffusion experiments of photocured polymer dispersed liquid crystals are conducted by spatially resolved infrared microspectroscopy. The solubility limits of a UV curable PDLC system comprising low molecular weight liquid crystal(E7) and a photocurable monomer (NOA65) are determined.; In essence, IR microspectroscopy is proven to be a powerful tool for the quantitative characterization of the solubility limits of PDLC systems.