Poly(1-vinyl-1,2,4-triazolium) poly(ionic liquid)s: synthesis and the unique behavior in loading metal ions

Herein we report the synthesis of a series of poly(4-alkyl-1-vinyl-1,2,4-triazolium) poly(ionic liquid)s either via straightforward free radical polymerization of their corresponding ionic liquid monomers, or via anion metathesis of the polymer precursors bearing halide as counter anion. The ionic liquid monomers were first prepared via N-alkylation reaction of commercially available 1-vinyl-1,2,4-triazole with alkyl iodides, followed by anion metathesis with targeted fluorinated anions. The thermal properties and solubilities of these poly(ionic liquid)s have been systematically investigated. Interestingly, it was found that the poly(4-ethyl-1-vinyl-1,2,4-triazolium) poly(ionic liquid) exhibited an improved loading capacity of transition metal ions in comparison with its imidazolium counterpart.Comment: 18 pages, 9 figure

Liquid - liquid flows in microchannels

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.In this work the flow patterns are investigated during the flow of an ionic liquid and deionized water mixture in a glass microchannel (0.2mm I.D) for two different inlet configurations (T- and Yjunction). The density, viscosity and surface tension of the ionic liquid [C4mim][NTf2] are 1420kg/m3 , 0.029Pa·s and 31.92mN/m respectively. The water phase has a density of 1000kg/m3, a viscosity of 0.001Pa·s and a surface tension of 73,69mN/m. In most of the patterns observed water was the continuous phase with the ionic liquid forming plugs or a mixture of plugs and drops within it. With the Y-junction and at high mixture velocities a separated pattern was observed with the two fluids flowing in parallel along the channel for the middle range of ionic liquid fractions, while water dispersed as drops was found at high ionic liquid fractions. Pressure drop was measured during regular plug flow which revealed that for the same ionic liquid superficial velocity the pressure drop was lower when it flowed in a mixture with water than when it was on its own in the channel. For a xonstant ionic liquid flow rate, pressure drop decreased as the ionic liquid fraction increased.The project is funded by the Engineering and Physical Sciences Research Council (EPSRC) and the Energy Institute at UCL

High-performance nn-type organic field-effect transistors with ionic liquid gates

High-performance $n$-type organic field-effect transistors were developed with ionic-liquid gates and N,N$^"$-bis(n-alkyl)-(1,7 and 1,6)-dicyanoperylene-3,4:9,10-bis(dicarboximide)s single-crystals. Transport measurements show that these devices reproducibly operate in ambient atmosphere with negligible gate threshold voltage and mobility values as high as 5.0 cm$^2$/Vs. These mobility values are essentially identical to those measured in the same devices without the ionic liquid, using vacuum or air as the gate dielectric. Our results indicate that the ionic-liquid and $n$-type organic semiconductor interfaces are suitable to realize high-quality $n$-type organic transistors operating at small gate voltage, without sacrificing electron mobility

Triphilic ionic-liquid mixtures: fluorinated and non-fluorinated aprotic ionic-liquid mixtures

We present here the possibility of forming triphilic mixtures from alkyl- and fluoroalkylimidazolium ionic liquids, thus, macroscopically homogeneous mixtures for which instead of the often observed two domainspolar and nonpolarthree stable microphases are present: polar, lipophilic, and fluorous ones. The fluorinated side chains of the cations indeed self-associate and form domains that are segregated from those of the polar and alkyl domains. To enable miscibility, despite the generally preferred macroscopic separation between fluorous and alkyl moieties, the importance of strong hydrogen bonding is shown. As the long-range structure in the alkyl and fluoroalkyl domains is dependent on the composition of the liquid, we propose that the heterogeneous, triphilic structure can be easily tuned by the molar ratio of the components. We believe that further development may allow the design of switchable, smart liquids that change their properties in a predictable way according to their composition or even their environment

Ambipolar transport in bulk crystals of a topological insulator by gating with ionic liquid

We report that the ionic-liquid gating of bulk single crystals of a topological insulator can control the type of the surface carriers and even results in ambipolar transport. This was made possible by the use of a highly bulk-insulating BiSbTeSe2 system where the chemical potential is located close to both the surface Dirac point and the middle of the bulk band gap. Thanks to the use of ionic liquid, the control of the surface chemical potential by gating was possible on the whole surface of a bulk three-dimensional sample, opening new experimental opportunities for topological insulators. In addition, our data suggest the existence of a nearly reversible electrochemical reaction that causes bulk carrier doping into the crystal during the ionic-liquid gating process.Comment: 7 pages, 6 figures, 2 tables; significantly expanded version to fully discuss the gating process and its side effects; published in PR

Phosphonium based poly(ionic liquid)/ ionic liquid membranes for high temperature ion conductance: Influence of ionic liquid structure and loading on membrane stability and performance

Ionic liquids are novel materials for use in catalysis, electrochemistry, and energy storage due to their high thermal and chemical stability as well as high ion conductivity. Development of ionic liquid monomers allows the production of polymeric ionic liquid materials which combine the versatility of ionic liquid materials with the mechanical stability of traditional polymeric membranes. Previous research has shown that inclusion of non-polymerizable free-ionic liquid in polymer and ionic liquid monomer formulations allows an increase in mechanical stability and ionic liquid properties. Further, free-ionic liquid loading improves the flexibility of membrane materials through hybridization of material properties. This research focused on the influence of ionic liquid structure and loading in poly(ionic liquid)/ionic liquid materials with regards to ion conductivity and mechanical stability. This material complex has been successful at the development of free-standing membranes with thicknesses down to 10 μm. Reduction of ionic liquid alkyl chain length resulted in increased thermal stability of membrane materials with negligible changes in ion conductivity performance at high temperatures. Further, an increase of free-ionic liquid loading resulted in an increase in overall ion conductivity and membrane mechanical stability. However, at ionic liquid loadings greater than 40 wt%, mechanical stability diminishes due to ionic liquid leakage. Through the use of poly(ionic liquid)/ionic liquid composite materials, novel membranes can be developed for a multitude of applications with greater flexibility, tunability, and performance. Please click Additional Files below to see the full abstract