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Chemical Physics Publications

Molecules

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Full-Text Articles in Physics

Pattern-Stabilized Decorated Polar Liquid-Crystal Fibers, Alexey Eremin, Ulrike Kornek, Stephan Stern, Ralf Stannarius, Fumito Araoka, Hideo Takezoe, Hajnalka Nadasi, Wolfgang Weissflog, Antal Jakli Jul 2012

Pattern-Stabilized Decorated Polar Liquid-Crystal Fibers, Alexey Eremin, Ulrike Kornek, Stephan Stern, Ralf Stannarius, Fumito Araoka, Hideo Takezoe, Hajnalka Nadasi, Wolfgang Weissflog, Antal Jakli

Chemical Physics Publications

Geometric frustration gives rise to new fundamental phenomena and is known to yield the formation of exotic states of matter, such as incommensurate crystals, modulated liquid-crystalline phases, and phases stabilized by defects. In this Letter, we present a detailed study of polar structure of freely suspended fluid filaments in a polarization modulated liquid-crystal phase. We show that a periodic pattern of polarization-splay stripes separated by defect boundaries and decorating smectic layers can stabilize the structure of fluid fibers against the Rayleigh-Plateau instability. The instability is suppressed by the resistance of the defect structure to a radial compression of the cylindrical ...


Second-Harmonic Generation In A Bent-Core Nematic Liquid Crystal, Seung Ho Hong, J. C. Williams, Robert J. Twieg, Antal Jakli, Jim T. Gleeson, Samuel N. Sprunt, Brett Ellman Oct 2010

Second-Harmonic Generation In A Bent-Core Nematic Liquid Crystal, Seung Ho Hong, J. C. Williams, Robert J. Twieg, Antal Jakli, Jim T. Gleeson, Samuel N. Sprunt, Brett Ellman

Chemical Physics Publications

Second-Second-harmonic generation (SHG) is studied in the magnetically aligned nematic phase of a bent-core liquid crystal (BCN) and compared to similar measurements made on a conventional rodlike (calamitic) nematic compound. The second-harmonic (SH) light detected from both materials is predominantly due to scattering and therefore incoherent. Results on the calamitic are consistent with a polarization induced by ordinary director fluctuations in the nematic phase. However, the SH scattering collected in the BCN exhibits a different temperature and angular dependence. We discuss how these differences could arise from the effects of short-range correlated, smectic-C-type molecular clusters, which have been detected in ...


Dielectric Properties Of Mixtures Of A Bent-Core And A Calamitic Liquid Crystal, Peter Salamon, Nandor Éber, Agnes Buka, Jim T. Gleeson, Samuel N. Sprunt, Antal Jakli Mar 2010

Dielectric Properties Of Mixtures Of A Bent-Core And A Calamitic Liquid Crystal, Peter Salamon, Nandor Éber, Agnes Buka, Jim T. Gleeson, Samuel N. Sprunt, Antal Jakli

Chemical Physics Publications

Dielectric spectroscopy measurements have been performed on a bent-core nematic liquid crystal and on its binary mixtures with a calamitic nematic. We have detected more dispersions in the bent-core compound than in the calamitic one, including one at an unusually low frequency of a few kilohertz. The dispersions detected in the mixtures have been identified and the spectra have been split into contributions of the constituents. In order to connect the dielectric increment with the molecular dipole moment we have applied a sophisticated conformational calculation not performed before for a large, flexible mesogen molecule with numerous polar groups.


Structure And Dynamics Of Liquid Crystalline Pattern Formation In Drying Droplets Of Dna, Ivan I. Smalyukh, O. V. Zribi, Jc Butler, Oleg Lavrentovich, G.C.L. Wong May 2006

Structure And Dynamics Of Liquid Crystalline Pattern Formation In Drying Droplets Of Dna, Ivan I. Smalyukh, O. V. Zribi, Jc Butler, Oleg Lavrentovich, G.C.L. Wong

Chemical Physics Publications

We investigate the formation of ringlike deposits in drying drops of DNA. In analogy with the colloidal "coffee rings," DNA is transported to the perimeter by the capillary flow. At the droplet edge, however, DNA forms a lyotropic liquid crystal (LC) with concentric chain orientations to minimize the LC elastic energy. During the final stages of drying, the contact line retracts, and the radial stress causes undulations at the rim that propagate inward through the LC and form a periodic zigzag structure. We examine the phenomenon in terms of a simple model based on LC elasticity.


Pretransitional Nematic Ordering In Liquid Crystals With Dispersed Polymer Networks, Y. K. Fung, A. Borstnik, S. Zumer, Deng-Ke Yang, J. William Doane Feb 1997

Pretransitional Nematic Ordering In Liquid Crystals With Dispersed Polymer Networks, Y. K. Fung, A. Borstnik, S. Zumer, Deng-Ke Yang, J. William Doane

Chemical Physics Publications

The birefringence induced by partially ordered polymer networks dispersed in an isotropic phase of liquid crystals is studied. Polymer networks were formed by the polymerization of 1-4 % mixtures of prepolymer in the nematic phase of liquid crystals. The partial nematic (paranematic) ordering is analyzed in terms of the Landau-de Gennes approach using a simple model of an array of thin fibrils, which can, on a large scale, form bundles of polymer-rich material. The comparison of the theory and birefringence data clearly shows that the main building bloc of the network is a few nanometers thick fibril. The average thickness of ...