Interfacial Behavior of Thin Ionic Liquid Films on Mica

Deyko, Alexey; Cremer, Till; Rietzler, F.; Perkin, Susan; Crowhurst, Lorna; Welton, Tom; Steinrück, Hans‐Peter; Maier, Florian

doi:10.1021/jp3115397

Cited by 60 publications

(113 citation statements)

References 52 publications

Supporting

Mentioning

105

Contrasting

Order By: Relevance

“…[31][32][33][34][35][36][37][38][39] More recent Angle-Resolved X-ray Photoelectron Spectroscopy (ARXPS) studies on ultrathin imidazolium-based ionic liquid films give information on the molecular arrangement of the ions on the surface at low loadings. [40][41][42] For example, a bilayered structure for the first [C 2 mim][NTf 2 ] layer on glass is reported, with the cation in direct substrate contact, and the anion arranged above the cation, which agrees well with molecular dynamics simulations. 40,43 At higher loadings, three-dimensional island growth on top of the first layer is observed.…”

Section: Introductionsupporting

confidence: 64%

Solid–ionic liquid interfaces: pore filling revisited

Heinze

Zill

Matysik

et al. 2014

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

The properties of ionic liquids on ordered and non-ordered mesoporous silicas (silica gel, MCM-41, SBA-15) were studied by nitrogen sorption, mercury intrusion and thermogravimetric analyses, as well as (129)Xe-NMR spectroscopy. The ionic liquids investigated are based on the 1-hexyl-3-methylimidazolium cation, which was combined with anions of low (bis(trifluoromethanesulfonyl)imide; [NTf2](-)), medium (trifluoromethylsulfonate; [CF3SO3](-)) to high (acetate; [OAc](-)) basicity. The surface coverage depends on both the type of ionic liquid and support used. This results not only in layer or droplet formation, but also in different physico-chemical properties of the ionic liquid when compared to the bulk, depending mainly on the strength of interaction at the interface. Furthermore, the mercury intrusion analysis of mesopores is shown not to be suitable for supported ionic liquids.

show abstract

Section: Introductionsupporting

confidence: 64%

Solid–ionic liquid interfaces: pore filling revisited

Heinze

Zill

Matysik

et al. 2014

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

show abstract

“…The growth mode of [C 1 C 1 Im][Tf 2 N] on the checkerboard-type sandwich structure on Ni(111) [156] and also for [C 2 C 1 Im][Tf 2 N] on glass [150] occurs in threedimensional islands. Finally, ARXPS measurements of the growth of [C 1 C 1 Im][Tf 2 N] on freshly air-cleaved mica surfaces showed a pronounced dependence of the initial IL adsorption behaviour on carbon precoverages: On clean mica, 3D growth (complete dewetting) occurs, whereas on a fully carbon-covered surface, initially a complete 2D wetting layer forms, followed by 3D growth [163].…”

Section: Ionic Liquids In Catalysis 391mentioning

confidence: 99%

Ionic Liquids in Catalysis

2014

Self Cite

View full text Add to dashboard Cite

Ionic liquids (ILs), salts with melting points below 100°C, represent a fascinating class of liquid materials typically characterized by an extremely low vapor pressure. Besides their application as new solvents or as electrolytes for electrochemical purposes, there are two important concepts of using ILs in catalysis: Liquid-liquid biphasic catalysis and IL thin film catalysis. Liquid-liquid biphasic catalysis enables either a very efficient manner to apply catalytic ILs, e.g. in Friedel-Crafts reactions, or to apply ionic transition metal catalyst solutions. In both cases, phase separation after reaction allows an easy separation of reaction products and catalyst re-use. One problem of liquidliquid biphasic catalysis is mass transfer limitation. If the chemical reaction is much faster than the liquid-liquid mass transfer the latter limits the overall reaction rate. This problem is overcome in IL thin film catalysis where diffusion pathways and thus the characteristic time of diffusion are short. Here, Supported Ionic Liquid Phase (SILP) and Solid Catalyst with Ionic Liquid Layer (SCILL) are the two most important concepts. In both, a high surface area solid substrate is covered with a thin IL film, which contains either a homogeneously dissolved transition metal complex for SILP, or which modifies catalytically active surface sites at the support for SCILL. In each concept, interface phenomena play a very important role: These may concern the interface of an IL phase with an organic phase in the case of liquidliquid biphasic catalysis. For IL thin film catalysis, the interfaces of the IL with the gas phase and with catalytic nanoparticles and/or support materials are of critical importance. It has recently been demonstrated that these interfaces and also the bulk of ILs can be investigated in great detail using surface science studies, which greatly contributed to the fundamental understanding of the catalytic properties of ILs and supported IL materials. Exemplary results concerning the IL/vacuum or IL/gas interface, the solubility and surface enrichment of dissolved metal complexes, the IL/support interface and the in situ monitoring of chemical reactions in ILs are presented.

show abstract

“…[27,[30][31][32][33] Due to their low vapor pressure, ILs are candidates for precursor film studies and the first study of precursor films spreading ahead of macroscopic droplets of imidazolium-based ILs (on smooth mica surfaces) was carriedo ut by Beattie et al [34] Additionally,i nr ecent literature reports there are several publications dedicated to interfacial tension studies, including the measuremento fc ontact anglesf ormed by various ILs on different solid substrates. [27,[30][31][32][33] Due to their low vapor pressure, ILs are candidates for precursor film studies and the first study of precursor films spreading ahead of macroscopic droplets of imidazolium-based ILs (on smooth mica surfaces) was carriedo ut by Beattie et al [34] Additionally,i nr ecent literature reports there are several publications dedicated to interfacial tension studies, including the measuremento fc ontact anglesf ormed by various ILs on different solid substrates.…”

mentioning

confidence: 99%

“…[42,43] To enable ac omparison between all results, Figure 3A presents as chematic representation of the number of droplets formed per mm 2 of surface area and Figure 3B presents the surfaceoccupation (surfacec overage) percentage as af unction of each IL of the [C n C 1 im][Ntf 2 ]s eries. [33] As ap ossible explanation for the dropletm orphology changes with chain length, the whole ITO-coated glass substrate is first wettedb y one strongly adsorbed monolayer of ionic liquid and further IL is deposited onto as upport with the interface, which exhibits as urface free energy that depends on the nature of this monolayer.P resumably,t his interfacial free energyd ecreases with increasing alkyl chain lengthsu pton = 6-8. According to Figure 3, for ad epositiont ime of 30 min, the number of droplets formed increases linearly between [C 1 C 1 im] [Ntf 2 ]a nd [C 6 C 1 im][Ntf 2 ]( r 2 = 0.9993).…”

mentioning

confidence: 99%

Morphology of Imidazolium‐Based Ionic Liquids as Deposited by Vapor Deposition: Micro‐/Nanodroplets and Thin Films

2016

View full text Add to dashboard Cite

The morphology of micro-and nanodroplets and thin films of ionic liquids (ILs) prepared through physical vapor deposition is presented. The morphology of droplets deposited on indium-tin-oxide-coated glass is presented for the extended 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([CnC1im][Ntf2]; n= 1-8) series, and the results show the nano-structuration of ILs. The use of in-vacuum energetic particles enhances/increases the nanodroplets mobility/coalescence mechanisms and can be a pathway to the fabrication of thin IL films. Ionic liquids (ILs) are a family of materials that offer a range of properties that can be adjusted to optimize their performance in a diversity of technological applications. [1-3] ILs share common characteristics, such as ionic conductivity, good thermal stability, and extremely low vapor pressure at room temperature. [4-6] In recent years, extensive studies of the thermo-physical properties of ILs have shown that almost none of these properties are shared across the IL range due to structural/nanostructural modifications. [7-9] ILs are becoming particularly attractive for many applications, such as solvents for electro-chemistry (electrically conducting fluids, electrolytes), sealants, chemical industry, gas handling, pharmaceuticals, cellulose processing, dye-sensitized solar cells, waste recycling, batteries, dispersion of nanomaterials, and electrode-electrolyte interfaces in high-vacuum systems. [10-15] Recently, the liquid/vacuum and liquid/solid interfaces of ILs have been of great relevance for most of the above-mentioned applications, and model surface studies and molecular orientation/ordering investigations of ILs have been performed on surfaces with different chemical properties: Au, Ni, silica, graphene, alumina, glass, and mica. [16-20] In some cases, thin films of ILs have been prepared by using impregnation techniques with solutions of ILs in volatile solvents, followed by solvent removal by evaporation. Thus, nanostructures of ILs can be prepared by spin/dip-coating methods and the films have low thicknesses and exceptional lubrication characteristics. [20] In recent years, the focus has been on physical vapor deposition (PVD) of ILs on different surfaces [16, 18, 19]

show abstract

Interfacial Behavior of Thin Ionic Liquid Films on Mica

Cited by 60 publications

References 52 publications

Solid–ionic liquid interfaces: pore filling revisited

Solid–ionic liquid interfaces: pore filling revisited

Ionic Liquids in Catalysis

Morphology of Imidazolium‐Based Ionic Liquids as Deposited by Vapor Deposition: Micro‐/Nanodroplets and Thin Films

Contact Info

Product

Resources

About