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Full-Text Articles in Physics

Effect Of Trans-Cis Photoisomerization On Phase Equilibria And Phase Transition Of Liquid-Crystalline Azobenzene Chromophore And Its Blends With Reactive Mesogenic Diacrylate, Namil Kim, Quan Li, Thein Kyu Apr 2014

Effect Of Trans-Cis Photoisomerization On Phase Equilibria And Phase Transition Of Liquid-Crystalline Azobenzene Chromophore And Its Blends With Reactive Mesogenic Diacrylate, Namil Kim, Quan Li, Thein Kyu

Thein Kyu

Photoisomerization-induced phase transition of neat liquid-crystalline azobenzene chromophore (LCAC) and its effect on phase diagrams of its mixtures with reactive mesogenic diacrylate monomer (RM257) have been investigated experimentally and theoretically. Upon irradiation with ultraviolet light, the nematic phase of LCAC transformed to isotropic, while the crystal phase showed corrugated textures on the surface (i.e., ripples). The phase-transition temperatures and corresponding morphologies of the blends have been investigated by means of differential scanning calorimetry and optical microscopy. A theoretical phase diagram of a binary nematic and crystalline system was constructed by self-consistently solving the combined free energies of Flory-Huggins, Maier-Saupe, and …


Spatio-Temporal Growth Of Nematic Domains In Liquid Crystal Polymer Mixtures, Hao-Wen Chiu, Thein Kyu Apr 2014

Spatio-Temporal Growth Of Nematic Domains In Liquid Crystal Polymer Mixtures, Hao-Wen Chiu, Thein Kyu

Thein Kyu

Dynamics of phase separation and morphology development in mixtures of a low molar mass liquid crystal (LC) and a polymer have been investigated theoretically in comparison with experimental results. In the theoretical model, the combined free-energy densities of Flory-Huggins theory for isotropic mixing and Maier-Saupe theory for nematic ordering have been incorporated into the time-dependent Ginzburg-Landau equation (type C). The temporal evolution of the structure factor and the emergence of phase-separated liquid crystal domains have been simulated on the basis of an explicit central difference method based on a square lattice (128 x 128) with a periodic boundary condition. Of …


Observation Of Novel Liquid-Crystalline Phase Above The Bulk-Melting Temperature, Keshav Gautam, Satyendra Kumar, Didier Wermeille, Doug Robinson, Ali Dhinojwala Apr 2014

Observation Of Novel Liquid-Crystalline Phase Above The Bulk-Melting Temperature, Keshav Gautam, Satyendra Kumar, Didier Wermeille, Doug Robinson, Ali Dhinojwala

Ali Dhinojwala

In this paper, we show that a noncrystalline but ordered smectic-like phase exists above the bulk-melting temperature (T-m) at poly(n-alkyl acrylates)-air interface. The surface ordered phase is one monolayer thick and undergoes a sharp transition from order to disorder 10degreesC above T-m for n=22. The presence of a surface phase that does not exist in the bulk has important implications in the design of thermally responsive adhesives.


Statistical Mechanics Of Wormlike Polymers From A New Generating Function. Ii. The Force-Elongation Relationship, Gustavo Carri Apr 2014

Statistical Mechanics Of Wormlike Polymers From A New Generating Function. Ii. The Force-Elongation Relationship, Gustavo Carri

Gustavo A. Carri

No abstract provided.