Alignment In Liquid-crystalline Phase Research Articles

Influence of liquid crystalline ordering on the properties of selected cured nematic epoxy materials

Properties of liquid crystalline polymer networks depend on the structure of the reagents as well as on the density of cross-linking bonds, which – in turn – is affected by the degree of ordering of the molecules during the reaction. Changing external conditions (including temperature, time of curing and various factors enforcing orientation of the monomers, such as preparation of cell surface or magnetic field) one can obtain different products. The influence of these external factors on the properties of cured epoxy monomers is studied in this paper. Liquid crystalline polymer networks were obtained as a result of curing three different epoxy compounds with 4,4′-diaminodiphenylmethane (DDM). All the three monomers have nematic phases in wide range of temperatures. The process of cross-linking, the final product of curing and the pure monomers were examined using polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and wide-angle X-ray scattering (WAXS). Chemical structure of the products was confirmed using spectroscopic methods. The study demonstrates that setting up specific conditions for curing (a temperature corresponding to liquid crystallinity range of pure monomer and an external factor enforcing molecular alignment in liquid crystalline phase) may result in cured products with somewhat better organisation at the molecular level.

Cuprite Nanowires by Electrodeposition from Lyotropic Reverse Hexagonal Liquid Crystalline Phase

Cuprite (Cu2O) nanowires with diameter of 25−100 nm were electrodeposited from anionic surfactant sodium bis(2-ethylhexyl) sulfosuccinate reverse hexagonal liquid crystalline phase. The nanowires can be grown to up to tens of micrometers in length by simply changing the electrodeposition time. Resistivity measurements suggest improved alignment of the reverse hexagonal liquid crystalline phase under electric field during electrodeposition. The enhanced alignment of the liquid crystalline phase appears essential for the growth of nanowires with high aspect ratio. This new synthesis approach is fast and simple, and a great variety of organized assemblies are potentially available by simply adjusting the liquid crystal type and composition.