Search results for "Liquid Crystal"
showing 10 items of 492 documents
Improving the mesomorphic behaviour of supramolecular liquid crystals by resonance-assisted hydrogen bonding
2019
A systematic structure-property relationship study on hydrogen-bonded liquid crystals was performed, revealing the impact of resonance-assisted hydrogen bonds (RAHBs) on the self-assembling behavior of the supramolecular architecture. The creation of a six-membered intramolecular hydrogen-bonded ring acts as a counterpart to the self-organization between hydrogen bond donators and acceptors and determines thus the suprastructure. Variation of the hydrogen-bonding pattern allowed us to significantly improve the temperature range of the reported liquid crystalline assemblies.
Accurate color predictability based on a spectral retardance model of a twisted-nematic liquid-crystal display
2011
Abstract In this work we present the application of a simple physical model to accurately predict the broadband spectral transmittance and colorimetric properties of a twisted-nematic liquid crystal display (TNLCD). We spectroscopically calibrate the retardance parameters to evaluate the spectrum of the light transmitted by a TNLCD sandwiched between two linear polarizers. When the TNLCD is illuminated with a broadband light source, the full spectrum can be predicted as a function of the addressed gray level for any arbitrary orientation of the polarizers. Thus, the color of the transmitted light can be also be estimated with very good accuracy. As an example, a polarizers' configuration is…
Helix Inversion Controlled by Molecular Motors in Multistate Liquid Crystals.
2020
Unravelling the rules of molecular motion is a contemporary challenge that promises to support the development of responsive materials and is likely to enhance the understanding of functional motion. Advances in integrating light‐driven molecular motors in soft matter have led to the design and realization of chiral nematic (cholesteric) liquid crystals that can respond to light with modification of their helical pitch, and also with helix inversion. Under illumination, these chiral liquid crystals convert from one helical geometry to another. Here, a series of light‐driven molecular motors that feature a rich configurational landscape is presented, specifically which involves three stable …
Nanostructuring with a crosslinkable discotic material.
2007
A high-yielding synthesis afforded a hexa-peri-hexabenzocoronene carrying acrylate units at the end of six attached alkyl spacers. The polymerization of these acrylate moieties could be initiated with thermal energy and through direct photoactivation without the addition of a photoinitiator. This allowed the organization of the liquid-crystalline material to be fixed in either the crystalline state or the mesophase, which preserved the organization in the respective phase. The use of a focused synchrotron beam permitted selected regions of a thin film to be rendered insoluble. After "developing" the film in this lithographic process by dissolving the soluble, unpolymerized material, defined…
Programmable Supercontinuum Laser Spectrum Generator Based on a Liquid-Crystal on Silicon Spatial Light Modulator
2021
Supercontinuum (SC) lasers combine a broadband light spectrum with the unique properties of single-mode lasers. In this work we present an optical system to spectrally filter a SC laser source using liquid-crystal on silicon (LCoS) spatial light modulators (SLM). The proposed optical system disperses the input laser and the spectrally separated components are projected onto the LCoS-SLM, where the state of polarization of each wavelength is separately modulated. Finally, recombining the modulated spectral components results in an output laser source where the spectrum can be controlled dynamically from a computer. The system incorporates two branches to independently control the visible (VI…
The supramolecular self-organization of an amphotropic cholesterol derivative Micelles, liposomes and liquid-crystalline phases
1993
Abstract The cholesterol derivative tetraethoxycholesteryl semisuccinate is both a mesogen and an amphiphile. This combination of both molecular prerequisites permits two types of supramolecular self-organization: the formation of a thermotropic liquid-crystalline phase and of various forms of aggregates in contact with water or other solvents. Depending on the pH of the aqueous medium the compound self organizes in micelles or liposomes. At high concentrations lyotropic liquid-crystalline phases are obtained. The formation of liposomes and lyotropic phases is not restricted to water as a solvent but can also be induced in pure organic media such as water-free diethyleneglycol. Due to the b…
Functional liquid crystalline particles and beyond
2019
ABSTRACTRecently the preparation and handling of liquid crystalline (LC) particles, which cover the size from some 100 nano-meters to micro- and millimetres found more interest. This review describ...
Preparation of cholesteric particles from cellulose derivatives in a microfluidic setup
2011
A microfluidic setup was used to process lyotropic cholesteric liquid crystalline mixtures of cellulose derivatives into spherical particles in the micrometre scale. By the method of co-flowing injection, monodisperse droplets of the liquid crystal, dispersed in an aqueous carrier fluid, were prepared. Polymerization of the acrylic solvent with UV-light fixed the orientation obtained by the flowing motion. The resulting particles were characterized by polarizing optical microscopy.
Interfacial Self-Assembly of Amphiphilic Dual Temperature Responsive Actuating Janus Particles
2018
Synthesis and physico-chemical characterization of gold nanoparticles softly coated by AOT
2006
Size-controlled gold nanoparticles/surfactant stable systems were prepared by the combined action of the solvated metal atom dispersion (SMAD) technique and confinement in anhydrous sodium bis(2-ethylhexyl)sulfosuccinate (AOT) micellar solution. From liquid samples, by evaporation of the organic solvent, solid gold nanoparticle-surfactant liquid crystals composites were obtained. Sample characterization was performed by X-ray diffraction (SAXS and WAXS), XPS spectroscopy and UV-vis-NIR spectroscopy. All experimental data consistently revealed the coexistence of two gold nanoparticle size populations: bigger nanoparticles (size 20-50 angstrom) and smaller ones (size of few angstrom). The two…