Search results for "liquid"

ChemInform Abstract: Liquid-Crystalline Ordering as a Concept in Materials Science: From Semiconductors to Stimuli-Responsive Devices

2013

While the unique optical properties of liquid crystals (LCs) are already well exploited for flat-panel displays, their intrinsic ability to self-organize into ordered mesophases, which are intermediate states between crystal and liquid, gives rise to a broad variety of additional applications. The high degree of molecular order, the possibility for large scale orientation, and the structural motif of the aromatic subunits recommend liquid-crystalline materials as organic semiconductors, which are solvent-processable and can easily be deposited on a substrate. The anisotropy of liquid crystals can further cause a stimuli-responsive macroscopic shape change of cross-linked polymer networks, w…

1978

Phase behavior of discotic liquid crystalline polymers and related model compounds

1990

Dielectric Relaxation Measurements and X-Ray Investigations of Liquid Crystalline Side-Chain Polymers

1985

In the last few years several liquid crystalline side-chain polymers have been synthesized,1 – 4 which combine the properties of low molecular weight liquid crystals with those of polymers.5 – 9

1987

X-ray scattering experiments on oriented polysiloxanes with paired mesogens and different distances between these swallow-tailed side groups show a remarkable dependence of the smectic monolayer thickness on the degree of dilution, whereas the interplanar distance of the side groups remain nearly constant. Due to the dominating interaction of the mesogenic moieties, the flexible main chain is forced to take part in the layer formation. A packing model is proposed to explain the results of the X-ray studies. For polymers with five or more dimethylsiloxane copolymer segments, a diffuse scattering appears in the smectic as well as in the isotropic phase. This scattering is independent of the o…

Liquid crystalline polymers and elastomers

2002

The results of experiments and theory correlate increasingly well in the investigation of liquid crystalline polymers. Current work focuses on rheology and the behavior of blends of thermotropic LC polymers, due to reemerging economic interest in these materials. Research on liquid crystalline elastomers concentrates on potential applications such as artificial muscles and lasing.

Liquid crystal polymers from swallow-tailed mesogens

1990

Abstract Swallow-tailed compounds containing an acetylenic unit have been synthesized. Only those compounds with a three ring structure exhibited liquid-crystalline phases. The platinum catalysed addition of these monomers to compounds containing Si-H groups was used to synthesize polymeric materials. Only those polymers with the tetramethyldisiloxane unit showed mesophases. The synthesis, characterization, and phase behaviour are described.

No-flow temperature and solidification in injection molding simulation

2011

The no‐flow temperature (NFT) is a parameter representing the rheological solidification temperature of a polymer. A polymer, during injection molding filling stage, can stop its flow because of its high viscosity, although it is not yet fully solidified by means of glass transition or crystallization. The NFT is used in most of injection molding simulation packages: with this simple parameter it is possible to reduce the errors deriving from viscosity extrapolation at relatively low temperatures. The viscosity measurements for polymers are usually carried out at high temperatures, and the viscosity models can fail in prediction at temperatures close to the glass transition or crystallizati…

1,3-Dimethylimidazolium-2-carboxylate: the unexpected synthesis of an ionic liquid precursor and carbene-CO2 adductElectronic supplementary informati…

2002

1,3-Dimethylimidazolium-2-carboxylate is formed in good yield, rather than the anticipated organic salt, 1,3-dimethylimidazolium methyl carbonate, as the reaction product resulting from both N-alkylation and C-carboxylation of 1-methylimidazole with dimethyl carbonate; the crystal structure of the zwitterion exhibits π-stacked rings and two-dimensional sheets constructed by hydrogen-bonds from imidazolium-ring hydrogens to the carboxylate group.

Determining sulfur-containing amino acids by capillary electrophoresis: A fast novel method for total homocyst(e)ine human plasma

1999

A high-performance capillary electrophoresis (HPCE) method based on laser-induced fluorescence detection is presented here. It enables the determination of sulfur-containing amino acids within 15 min. Fluorescence of sulfur-containing amino acids in plasma is linear over a range of 50-150 micromol/L for L-methionine, 5-100 micromol/L for L-homocysteine, and 50-200 micromol/L for L-cysteine. For homocysteine, we were able to detect 1 fmol injected, equivalent to a plasma concentration of 10 nmol/L. A similar sensitivity is present for cysteine, an even lower one being found for methionine. The intra- and interassay relative standard deviations are < 1%. High-performance liquid chromatography…