Rod-like liquid crystals

A nematic liquid crystal cell, based on Merck Licrilite E202, was used in these experiments. The rod like liquid crystal molecules preferentially aligned themselves with each other and to an alignment surface in the liquid crystal device. Any birefringence. An, was given as the difference between the two orthogonal refractive indices. As a consequence, any resulting... 

Rodium complexes Rod-like liquid crystals Rod nulls Roelen reaction Rohypnol Roica... 

Rod-like liquid crystals - [LIQUID CRYSTALLINE MATERIALS] (Vol 15)... 

Rod-Like Liquid Crystals with Fluorinated Chains... 

Rod-Like Liquid Crystals with One (Semi)Perfluorinated Chain Double Layer Smectic Phases... 

Fig. 2 Left. The basic 2D structure in the rod-like liquid crystals made by strongly polar molecules (the dipole moment directions are represented by arrows). The asymmetric rod-like molecules tend to form double layer structures in order to compensate dipole moments. Since the thickness of a double layer is smaller than twice the thickness of a single layer the resulting stress in the system is relieved by the in-layer modulation. Right. 2D structures in polycatenar rod-like liquid crystals. The ribbon like structure is formed by the asymmetric polycatenar molecules. To accommodate the additional alkyl chains layers become slightly bent. Both structures possess the body centered crystallographic unit cell...

In 2003, Sugimoto and Kanie published what appears to be the first claim on the formation of nematic-like one-dimensional ordering in liquid crystal-nanoparticle hybrid materials. Different shapes of Ti02 nanoparticles were hybridized with two structurally different rod-like liquid crystal amines (one based on a cyanobiphenyl and a second with a fluorinated cyclohexylbiphenyl core), but only the combination of spindle-like Ti02 nanorods (with an aspect ratio greater than 10) with the... 

Figure 4.9 Elastic deformations of calamitic, rod-like liquid crystals in the nematic phase. The corresponding elastic elasticity constants are K, (splay), /<2 (twist), and Kj (bend). K, has the largest influence on the threshold voltage, of TN cells [23f].

These mesoporous molecular sieves are prepared using a liquid crystal templating mechanism in which micelles, which are assemblies of cationic alkyl trimethylammonium surfactants [CH3(CH2) N+(CH3)3] X , act as a template for the formation of the silicaceous material (Figure 6.2). In the silicate-rich aqueous solution, the hydrophobic tails of the surfactant cluster together, leaving the positively charged heads to form the outside of the rod-like liquid crystal micelles. The silicate anions are attracted to, and surround the micelles, aggregating into an open-framework amorphous solid, which precipitates. The solid is filtered off, and heated in air at up to 700 °C (calcination), which removes the surfactant and leaves the... 

New LCD technology from the US manufacturer Hewlett-Packard allows the low cost production of ultra-high resolution screens, which draw no power once an image is displayed. The company s engineers discovered that when liquid crystals are put in contact with polymer posts smaller than 1 pm across, the rod-like liquid crystals naturally align themselves around the posts either horizontally or tilted upward in a spiral around the post. Applying an electric field switches their position from horizontal (a dark pixel) to tilted (a lit pixel). Since both of these states are stable the liquid crystals stay where they are when the field is removed. 

Finally, phase biaxiality has been studied by dissolving deuterated solute molecules in discotic liquid crystals [3.32]. Since discotic liquid crystals have negative Ax, an aligned sample consisting of one type of deuteron will exhibit a planar powder pattern (Fig. 3.7) without the necessity of sample rotation as in the conventional rod-like liquid crystals. Two discotic phases, Drd and have been studied by spectral pattern simulation using nonzero [3.32]. 

As discussed in Sec. 2.1, the prototype of the rod-like liquid crystal molecule (1) consists of a rigid core substituted with terminal flexible substituents, and eventually small lateral substituents. In the last few years in particular many mesomorphic compounds that do not correspond to this formula have been synthesized. Such materials may be called unconventional liquid crystalline compounds [1,2]. 

Chapter II Phase Transitions in Rod-Like Liquid Crystals.23... 

Rod-like liquid crystals [1] have been known for more than a hundred years, the first one, cholesteryl benzoate, being discovered in 1888 by Reinitzer. In materials of this type, nematic N, cholesteric N and different lamellar mesophases such as SmA, SmC, SmF, and SmI are obtained. Beside these classical liquid crystals, thermotropic mesophases - consisting of two-dimensional aromatic flat molecules - that exhibit various columnar phases (e.g., Col, Coif, Colob) have been known since 1977 [2, 3], In these two types of systems, the lamellar and columnar phases are observed separately. So, it was interesting to examine the mesomorphic properties of the hybrid molecules, i.e., molecules with a long rodlike rigid core ending in two half-disc moieties (Fig. 1). In fact, the phasmids [4,5] fill... 

In addition to their lyotropic properties, Hpids can also behave as thermotropic liquid crystals in a similar fashion to the rod-like liquid crystal molecules described in Chapter 2. In aqueous solution, the primary organization of the lipid phase is lyotropic however, the internal structural organization of the bilayer will vary as a function of temperature. In thinking about these thermotropic Hpid phases, it is helpful to consider the lipid to be in the lamellar phase, then to vary the temperature of this phase and look at the effects of temperature on molecular ordering within the bilayer. Lyotropic organization itself is also dependent on temperature, but more weakly so. For the following discussion, assume that the Hpids are organized in a lamellar phase composed of stacked Hpid bilayers. 

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