Tunable Command Layers for Liquid Crystal Alignment

Abstract

A simple method for the construction of a stable, tunable, self-assembled command layer for liquid crystal display purposes is described. A pyridine-functionalized oligosiloxane spontaneously forms an anisotropic, grooved surface on indium-tin-oxide, enabling it to align liquid crystalline molecules. The pyridine functions act as seeds for the epitaxial growth of stacks of highly ordered zinc phthalocyanines, the height of which can be controlled. These stacks increase the interaction between the surface and the liquid crystalline matrix by amplifying the surface ordering into the liquid crystal bulk. By varying the height of the stacks, direct control over the properties of the liquid crystal domains is achieved. These properties can be further tuned by adding to the liquid crystal, micro-and nanomolar concentrations of nitrogencontaining compounds, which are capable of interacting with and dissolving the stacks. The procedures we describe offer possibilities to use such tunable systems in LCD-based sensor devices as well as in solar-cell applications.

Self‐Organization and Nanoscale Electronic Properties of Azatriphenylene‐Based Architectures: A Scanning Probe Microscopy Study

“…[5] Columnar nanostructures made up through p-p stacking of alkylated discotic building blocks are interesting, both as nanowires [5][6][7] , and as molecular systems forming (uniform) films with a high degree of molecular orientation. [8,9] The increasing size of the disk leads, on one hand, to a moderate enhancement of the electronic function because of a greater delocalization of the p states, but on the other hand, it is accompanied by a drastic limitation in processability, both from solution and from vacuum sublimation. [5] In this context, medium-sized disks, such as triphenylene derivatives, represent very interesting discotic molecules, because the ease of substitution in the peripheral positions allows solution processability (and hence a high level of purification) and self-organization into columnar nanostructures possessing relatively high charge-carrier mobilities.…”

Beam coupling in hybrid photorefractive inorganic-cholesteric liquid crystal cells: Impact of optical rotation

“…35 By utilizing this type of aligning, one could check how the beam coupling is sensitive to the anchoring. Finally, we raise the possibility of using an inhomogeneous cholesteric, in which there exists a pitch gradient.…”

“…(33), (36), and (37). We obtain expressions for propagating (left polarized) waves omitting in formulas (35) and (36) …”

Pyridine-Functionalized TiO2 Nanoparticles as a Sorbent for Preconcentration and Determination of Ultra-Trace Palladium Ion

“…Pyridine functionalizing agent was synthesized according to earlier report 12 and characterized by 1 H NMR. Briefly, 1.0 g of 4-pyridine carboxylic acid was suspended in 100 mL of dried CH 2 Cl 2 under nitrogen atmosphere and 10 mL of oxalyl chloride was slowly added to the mixture and was stirred for 12 h. Then CH 2 Cl 2 was removed under reduced pressure, and the residue was suspended again in 100 mL of dried CH 2 Cl 2 .…”

“…5 Since the key point in SPE is choosing adsorbent, several SPE methods based on sorbents such as different polymers 7 , silica 8 and Fe 3 O 4 9 have been developed. Compared to the other sorbents TiO 2 has attracted more attention due to its high surface area [10][11][12] .…”