DMR-9730405 Lubensky Liquid crystals are materials that possess properties, such as the ability to flow, associated with liquids, and properties, such as optical anisotropy, associated with crystalline solids. New liquid crystalline materials, new realizations of familiar phases, and even entirely new liquid crystalline phases are continually being discovered. In this grant theoretical research will be carried out on two general aspects of the physics of liquid crystals: chirality and layered structures. Chirality of the mesogens is reflected in a rich variety of equilibrium phases that include the cholesteric phase, the blue phases, ferroelectric smectic-C* phase, and the A and C twisted grain boundary phases. This research seeks to elucidate the relationship between the structural chirality of these phases and chirality at a microscopic level. Other problems that will be studied that are related to chirality include: chiral structures in columnar phases, chiral pathways from the nematic to smectic-A phase, and phase transitions to the twisted grain boundary C phase. A major part of the reseach will be devoted to the study of 2D smectic lattices that form from DNA segments that are intercalated between lipid bilayers. Coulomb forces lead to interactions between lattices in adjacent layers. These structures are important in gene-therapy research. A major focus of the proposed research will be to study the statistical and structural properties of these complexes. Models for these phases that interpolate between one- dimensional smectic and two-dimensional columnar phases and show promise of predicting new equilibrium phases characterized by orientational but not positional correlations between 2D DNA lattices will be explored. Phases exhibited by free standing smectic films will also be studied. %%% Liquid crystals are materials that possess properties, such as the ability to flow, associated with liquids, and properties, such as optical anisotropy, as sociated with crystalline solids. New liquid crystalline materials, new realizations of familiar phases, and even entirely new liquid crystalline phases are continually being discovered. Lubensky will continue his theoretical inquiry, in close connection with experiments, into traditional and novel new liquid crystalline materials. A central theme of this research involves the investigation of many of the rich variety of phases that occur in these materials and how fundamental symmetries, such as whether or not a molecule can be superimposed on its mirror image, and properties at the molecular level, influence macroscopic properties of observed phases. Of particular interest are novel phases involving DNA segments that play a major role in gene- therapy research and how a phase responds to an externally applied electric field. This research will also contribute to the training of the next generation of experts in these technologically promising materials. ***
