| The ability to manipulate, control, and capture the liquid crystalline molecular order in thin polymer films is of significant practical interest. One way to accomplish this task is to use reactive mesogen compounds, which are photo-polymerizable liquid crystal monomers. All of the known techniques employed to align low-molecular-weight liquid crystals, such as electric and magnetic fields, surfaces, shear forces, etc., can be applied to reactive mesogen systems prior to photo-polymerization. The unique feature of reactive mesogens is that this alignment imposed by external forces can be captured indefinitely by photo-polymerization, enabling the creation of sophisticated molecular architectures. Tailored planar films created from reactive mesogens have recently become an inconspicuous passive optical element in liquid crystal displays to resolve their long-standing viewing angle problem. When reactive mesogens are polymerized in non-reactive liquid crystals, many other exciting applications are possible, including bistable displays, switchable mirrors, and diffraction gratings.; The outline of this thesis is the following. After the introduction to the physics of low-molecular-weight liquid crystals (Chapter 1) and polymer systems (Chapter 2), we discuss composite systems of liquid crystal polymers and low-molecular-weight liquid crystals in Chapter 3 and Chapter 4. In particular, the Fréedericksz transition and the switching dynamics in polymer stabilized liquid crystals (PSLCs) and holographic-PSLCs are discussed. Holographic-PSLCs are proposed for strongly polarization-sensitive diffraction device applications. In Chapter 5, the dynamics of diffraction grating formation in a single component reactive mesogen system is studied. Finally, in Chapter 6, we discuss the novel polymer microstructures from reactive mesogens. Appendix A and Appendix B give explanations of grating (hologram) formation and reconstruction mechanisms. |
