Templating and Phase Behaviour of the Long Chain Ionic Liquid C16mimCl
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Helena Kaper
In the light of recent studies about the favourable sol–gel templating behaviour of the long chain ionic liquids (ILs) 1-hexadecyl-3-methylimidazolium chloride and -bromide (C16mimCl and C16mimBr) the phase behaviour of these ILs is investigated in detail and compared to common surfactants such as hexadecyltrimethylammonium chloride and -bromide (CTAC and CTAB). Specially developed small angle X-ray scattering (SAXS) evaluation approaches confirm a lamellar double-layer structure for crystalline C16mimCl of the ABACAB type. Presumably, the orientation of the head groups repeats in every second head group layer. Therefore, the imidazolium head group exhibits long range interactions on packing and templating, in contrast to the ammonium head group. The lyotropic phase behaviour is investigated via SAXS, isothermal titration calorimetry (ITC) and surface tension measurements. Interestingly, the phase diagrams of C16mimCl and CTAC are quite different, especially at higher concentration of surfactant: instead of a gel phase in the phase diagram of CTAC, a lamellar-hexagonal two phase region as well as a pure lamellar phase is found in the phase diagram of C16mimCl. The critical micellar concentration (cmc) and enthalpy of micellization (ΔmicH) show that the cmc for imidazolium based surfactants is slightly lower and ΔmicH is more exothermic than for the ammonium type surfactants. These results are able to account for the specialties observed in the sol–gel templating behavior.
© Oldenbourg Wissenschaftsverlag
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Artikel in diesem Heft
- Preface: 92nd Bunsenkolloquium – Physical Chemistry in Ionic Liquids
- Relaxation Dynamics upon Ultrashort UV Photo-Excitation of an Iodide Doped Ionic Liquid and of a Pure Lithium Iodide Melt
- Electrochemistry in Room Temperature Ionic Liquids: A Review and Some Possible Applications
- Electrochemical Deposition of Nanostructured Metals and Alloys from Ionic Liquids
- Coating of Mild Steel by Aluminium in the Ionic Liquid [EMIm]Tf2N and its Corrosion Performance
- Microviscosity and Micropolarity Effects of Imidazolium Based Ionic Liquids Investigated by Spin Probes Their Diffusion and Spin Exchange
- Semi-Empirical Methods to Predict the Physical Properties of Ionic Liquids: An Overview of Recent Developments
- Water Vibrational Bands as a Polarity Indicator in Ionic Liquids
- Probing Lithium and Alumina Impurities in Air- and Water Stable Ionic Liquids by Cyclic Voltammetry and In Situ Scanning Tunneling Microscopy
- The Static Dielectric Constant of Ionic Liquids
- A Comparative Study on the Electronic Structure of the 1-Ethyl-3-Methylimidazolium Bis(trifluoromethylsulfonyl)amide RT-Ionic Liquid by Electron Spectroscopy and First Principles Calculations
- Phase Separation in Solutions of Room Temperature Ionic Liquids in Hydrocarbons
- Surface Studies on the Ionic Liquid 1-Ethyl-3-Methylimidazolium Ethylsulfate Using X-Ray Photoelectron Spectroscopy (XPS)
- Templating and Phase Behaviour of the Long Chain Ionic Liquid C16mimCl
- Preparation of CdSe Quantum Dots in Ionic Liquids
- Electrochemistry at Negative Potentials in Bis(trifluoromethanesulfonyl)amide Ionic Liquids
- Enthalpies of Solution of Organic Solutes in the Ionic Liquids [Me3BuN][NTf2] and [EMIM][EtSO4]
- Electrodeposition of Metals for Micro- and Nanostructuring at Interfaces between Solid, Liquid and Gaseous Conductors: Dendrites, Whiskers and Nanoparticles
