Mesomorphic studies

Caffrey, M. Structural, Mesomorphic and Time-Resolved Studies of Biological Liquid Crystals and Lipid Membranes Using Synchrotron X-Radiation. 151, 75-109 (1989). 

The synthesis of well defined block copolymers exhibiting controlled molecular weight, low compositional heterogeneity and narrow molecular weight distribution is a major success of anionic polymerization techniques 6,7,14-111,112,113). Blocks of unlike chemical nature have a general tendency to undergo microphase separation, thereby producing mesomorphic phases. Block copolymers therefore exhibit unique properties, that prompted numerous studies and applications (e.g. thermoplastic elastomers). 

Lateral monofluorination of the p-alkoxyphenyl isocyanide system [XAu (CNC6H40C H2 +i)] (X = C1, Br, I), in ortho-(3-F) (6a) and meta-(2-F) (6b) positions relative to the alkoxy chain was also studied [18]. None of the free fluorinated ligands is a LC, but their gold complexes display mesomorphic properties. This is a typical case of a promesogenic ligand which yields a mesogen upon coordination to a metal. 

As indicated above in chiral mesophases, the introduction of a functional group in mesogenic stmctures offers the opportunity to achieve functional LCs. With this aim, mesomorphic crown-ether-isocyanide-gold(I) complexes (26) have been prepared recently [38]. The derivatives with one alkoxy chain show monotropic SmC mesophases at or close to room temperature. In contrast, the complexes with three alkoxy chains behave as monotropic (n = 4) or enantiotropic (n > 4) LCs. The structure of the mesophases could not be fully eluddated because X-ray diffraction studies in the mesophase were unsuccessful and mesophase characterization was made only on the basis of polarized optical microscopy. These complexes are luminescent not only in the solid state and in solution, but also in the mesophase and in the isotropic liquid state at moderate temperatures. The emission spectra of 26a with n=12 were... 

For example, Marder and co-workers [10] (among others) have studied liquid crystal mesophases induced by the presence of quadrupolar interactions between non-mesomorphic phenyl- and perfluorophenyl-containing moieties (e.g. 1). 

Mesomorphic dendrimers containing electroactive units have potential for construction of dendrimer based molecular switches. Deschenaux et al. reported [154] the synthesis and liquid-crystalline properties of a novel dendrimer containing six mesomorphic ferrocene units. Apart from exhibiting a broad enantiotropic smectic A phase as determined by polarized optical microscopy, DSC, and XRD studies, thermogravimetry revealed the excellent thermal stability of the macromolecule. 

This is the first reported study of the spinning of mesomorphic cellulose solutions, but no fiber properties were given. Quenin et al. (14) used a d -jet, wet spinning system to spin cellulose/MMNO-H20 solutions. Fiber properties equiv dent to the best viscose rayon fiber were obtained. 

Formation of band textures in HPC liquid crystalline solutions was studied by Navard (86) and Takaheshi et al. (94). Upon shearing, some polymeric liquid crystals develop a particular texture which is called "band texture" consisting of fine equidistant lines when viewed under crossed polars. In HPC-H2O mesomorphic solutions these bands are exhibited when the solution is allowed to freely relax after shearing. 

Burton DJ,Lu L (1997) Fluorinated Organometallic Compounds. 193 45 - 89 Caffrey M (1989) Structural, Mesomorphic and Time-Resolved Studies of Biological Liquid Crystals and Lipid Membranes Using Synchrotron X-Radiation. 151 75 -109 Canceill J, see Collet A (1993) 165 103 -129 Carbd R, see Besalu E (1995) 173 31-62... 

There has been an increasing interest in liquid crystals containing fluorine atoms because fluorination produces important changes in the melting temperatures, viscosity, birefringence, dielectric anisotropy and mesophase stability. This why structure-mesomorphism relationship studies were carried out in mono- and... 

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