1,10-Phenanthrolinium ionic liquid crystals

An experimental and computational study on the material dispersion of 1-alkyl-3-methylimidazolium tetrafluoroborate ionic liquids

The material dispersion of the [Ckmim][BF4] (k = 2, 3, 4, 6, 7, 8, 10) family of ionic liquids is measured at several temperatures over a broad spectral range from 300 nm to 1550 nm. The experimental curves are fitted to a modified three-resonance Sellmeier model to understand the effects of temperature and alkyl chain length on the dispersion behaviour. From the parameters of the fitting, we analyze the influence that the different constituents of these ionic liquids have on the dispersion behaviour. In addition, a semi-empirical approach combining simulated electronic polarizabilities and experimental densities for predicting the material dispersion is successfully tested by using a direct comparison with the experimental results. The limitations of this method are analyzed in terms of the molecular structure of the ionic liquids. The results of this work aim to increase our knowledge about how the molecular structure of an ionic liquid influences its material dispersion. Understanding this influence is fundamental to producing ionic liquids with tailored optical properties.

Dielectric properties of a bisimidazolium salt with dodecyl sulfate anion doped with carbon nanotubes

A new bisimidazolium salt with dodecyl sulfate as counterion has been designed and prepared. This salt shows a SmA phase that is stable at room temperature. The new ionic liquid crystal (ILC) was characterized by ¹H NMR, ¹³C NMR and IR spectroscopy. Its liquid crystalline properties were analyzed by polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and powder X-ray diffraction (XRD) studies. The dielectric spectra of the ILC doped with different concentrations of carbon nanotubes (CNT) were recorded over a wide frequency and temperature range of 10^-1 to 10⁷ Hz and 293-338 K, respectively. The values of the activation energy were found in the range of 0.46-0.61 eV; the characteristic time was obtained by fitting the spectra of the dielectric loss with the Havriliak-Negami functions. As a result of doping the ILC with CNT, the electric conductivity increases significantly. Ionic conductivity is dominant and it was indirectly observed through the electrode polarization (EP) effect. The very high dielectric permittivity values and the decrease of the electric conductivity at low frequencies confirm the presence of EP.

Bis-imidazolium salts with alkyl sulfates as counterions: synthesis and liquid crystalline properties

A series of flexibly linked bis-imidazolium salts with alkyl sulfate anions having different chain lengths (10, 12, 14) was investigated for their thermotropic behavior.

Ionic Liquid Crystals: Versatile Materials

This Review covers the recent developments (2005-2015) in the design, synthesis, characterization, and application of thermotropic ionic liquid crystals. It was designed to give a comprehensive overview of the "state-of-the-art" in the field. The discussion is focused on low molar mass and dendrimeric thermotropic ionic mesogens, as well as selected metal-containing compounds (metallomesogens), but some references to polymeric and/or lyotropic ionic liquid crystals and particularly to ionic liquids will also be provided. Although zwitterionic and mesoionic mesogens are also treated to some extent, emphasis will be directed toward liquid-crystalline materials consisting of organic cations and organic/inorganic anions that are not covalently bound but interact via electrostatic and other noncovalent interactions.

Laxative inspired ionic liquid lubricants with good detergency and no corrosion

1-Alkyl-3-methylimidazolium bis(2-ethylhexyl)sulfosuccinate (L-DOSS10n, n = 2, 4, 8) ionic liquids (ILs) were synthesized from dioctyl sodium sulfosuccinate (NaDOSS), which is a cheap, bulk available laxative medicine used for the treatment of constipation. The ILs showed lower corrosion levels and higher hydrolysis stabilities than conventional ILs such as 1-butyl-3-methyl imidazolium tetrafluoroborate (L-B104) and 1-butyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide (L-F104) due to their halogen-free characteristic. The tribological properties of the ILs were also better than those of L-B104 and L-F104 for various contacts. Thus, they can be used as replacements for conventional IL lubricants, which may solve the problems of corrosion and high cost to put conventional IL lubricants into industrial application. Coking test results indicated that the synthesized ILs have high deterging ability. Thus, these ILs may be used as lubricants that restrain carbonaceous deposition as well as oil sludge and varnish formation on the metal contacts during the sliding process. Moreover, the synthesized ILs can disperse, loosen, and remove the already formed harmful substances and keep the metal contacts clean.