Cubosomes from hierarchical self-assembly of poly(ionic liquid) block copolymers

Cubosomes are micro- and nanoparticles with a bicontinuous cubic two-phase structure, reported for the self-assembly of low molecular weight surfactants, for example, lipids, but rarely formed by polymers. These objects are characterized by a maximum continuous interface and high interface to volume ratio, which makes them promising candidates for efficient adsorbents and host-guest applications. Here we demonstrate self-assembly to nanoscale cuboidal particles with a bicontinuous cubic structure by amphiphilic poly(ionic liquid) diblock copolymers, poly(acrylic acid)-block-poly(4-vinylbenzyl)-3-butyl imidazolium bis(trifluoromethylsulfonyl)imide, in a mixture of tetrahydrofuran and water under optimized conditions. Structure determining parameters include polymer composition and concentration, temperature, and the variation of the solvent mixture. The formation of the cubosomes can be explained by the hierarchical interactions of the constituent components. The lattice structure of the block copolymers can be transferred to the shape of the particle as it is common for atomic and molecular faceted crystals

Study of an ammonia-based wet scrubbing process in a continuous flow system

A continuous gas and liquid flow, regenerative scrubbing process for CO{sub 2} capture was demonstrated at the bench-scale level. An aqueous ammonia-based solution captures CO{sub 2} from simulated flue gas in an absorber and releases a nearly pure stream of CO{sub 2} in the regenerator. After the regeneration, the solution of ammonium compounds is recycled to the absorber. The design of a continuous flow unit was based on earlier exploratory results from a semi-batch reactor, where a CO{sub 2} and N{sub 2} simulated flue gas mixture flowed through a well-mixed batch of ammonia-based solution. During the semi-batch tests, the solution was cycled between absorption and regeneration steps to measure the carrying capacity of the solution at various initial ammonia concentrations and temperatures. Consequentially, a series of tests were conducted on the continuous unit to observe the effect of various parameters on CO{sub 2} removal efficiency and regenerator effectiveness within the flow system. The parameters that were studied included absorber temperature, regenerator temperature, initial NH{sub 3} concentration, simulated flue gas flow rate, liquid solvent inventory in the flow system, and height of the packed-bed absorber. From this testing and subsequent testing, ammonia losses from both the absorption and regeneration steps were quantified, and attempts were made to maintain steady state during operations. Implications of experimental results with respect to process design are discussed

Understanding the effect of side groups in ionic liquids on carbon-capture properties: a combined experimental and theoretical effort

Ionic liquids are an emerging class of materials with applications in a variety of fields. Steady progress has been made in the creation of ionic liquids tailored to specific applications. However, the understanding of the underlying structure-property relationships has been slower to develop. As a step in the effort to alleviate this deficiency, the influence of side groups on ionic liquid properties has been studied through an integrated approach utilizing synthesis, experimental determination of properties, and simulation techniques. To achieve this goal, a classical force field in the framework of OPLS/Amber force fields has been developed to predict ionic liquid properties accurately. Cu(i)-catalyzed click chemistry was employed to synthesize triazolium-based ionic liquids with diverse side groups. Values of densities were predicted within 3% of experimental values, whereas self-diffusion coefficients were underestimated by about an order of magnitude though the trends were in excellent agreement, the activation energy calculated in simulation correlates well with experimental values. The predicted Henry coefficient for CO2 solubility reproduced the experimentally observed trends. This study highlights the importance of integrating experimental and computational approaches in property prediction and materials development, which is not only useful in the development of ionic liquids for CO2 capture but has application in many technological fields

Molecular Simulation and Experimental Study of CO₂ Absorption in Ionic Liquid Reverse Micelle

The structure and dynamics for CO₂ absorption in ionic liquid reverse micelle (ILRM) were studied using molecular simulations. The ILRM consisted of 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]­[BF₄]) ionic liquid (IL) as the micelle core, the benzylhexadecyldimethylammonium ([BHD]⁺) chloride ([Cl]⁻) was the cationic surfactant, and benzene was used as the continuous solvent phase in this study. The diffusivity values of this ILRM system were also experimentally determined. Simulations indicate that there is ion exchange between the IL anion ([BF₄]⁻) and the surfactant anion ([Cl]⁻). It was also found that the [bmim]­[BF₄] IL exhibits small local density at the interface region between the IL core and the [BHD]⁺ surfactant cation layer, which leads to a smaller density for the [bmim]­[BF₄] IL inside the reverse micelle (RM) compared with the neat IL. These simulation findings are consistent with experimental results. Both our simulations and experimental results show that [bmim]­[BF₄] inside the RM diffuses 5–26 times faster than the neat IL, which is partly due to the fast <i>particle</i> diffusion for the ILRM nanodroplet (IL and surfactant) as a whole in benzene solvent compared with neat [bmim]­[BF₄] diffusion. Additionally, it was found that [bmim]­[BF₄] IL solved in benzene diffuses 2 orders of magnitude faster than the neat IL. Lastly, simulations show that CO₂ molecules are absorbed in four different regions of the ILRM system, that is, (I) in the IL inner core, (II) in the [BHD]⁺ surfactant cation layer, (III) at the interface between the [BHD]⁺ surfactant cation layer and benzene solvent, and (IV) in the benzene solvent. The CO₂ solubility was found to decrease in the order II > III ∼ IV > I, while the CO₂ diffusivity and permeability decrease in the following order: IV > III > II > I

Toward a Materials Genome Approach for Ionic Liquids: Synthesis Guided by Ab Initio Property Maps

The Materials Genome Approach (MGA) aims to accelerate development of new materials by incorporating computational and data-driven approaches to reduce the cost of identification of optimal structures for a given application. Here, we use the MGA to guide the synthesis of triazolium-based ionic liquids (ILs). Our approach involves an IL property-mapping tool, which merges combinatorial structure enumeration, descriptor-based structure representation and sampling, and property prediction using molecular simulations. The simulated properties such as density, diffusivity, and gas solubility obtained for a selected set of representative ILs were used to build neural network models and map properties for all enumerated species. Herein, a family of ILs based on ca. 200 000 triazolium-based cations paired with the bis(trifluoromethanesulfonyl)amide anion was investigated using our MGA. Fourteen representative ILs spreading the entire range of predicted properties were subsequently synthesized and then characterized confirming the predicted density, diffusivity, and CO2 Henrys Law coefficient. Moreover, the property (CO2, CH4, and N-2 solubility) trends associated with exchange of the bis(trifluoromethanesulfonyl)amide anion with one of 32 other anions were explored and quantified

Highly cross-linked polyether-based 1,2,3-triazolium ion conducting membranes with enhanced gas separation properties

International audienceA series of cross-linked polyether-based 1,2,3-triazolium ion conducting membranes are prepared via the combination of thermally promoted Huisgen 1,3-dipolar cycloaddition of a dialkyne and a diazide poly(trimethylene ether glycol) monomers with in-situ N-alkylation of the resulting poly(1,2,3-triazole)s with varying contents of 1,10-diiododecane as cross-linking agent. The resulting free-standing membranes have T(g)s below -60 degrees C, T(d)s up to 230 degrees C, and Young's modulus up to 4.2 MPa. The overall combined reaction kinetics were studied by DSC yielding an activation energy of 76 kJ/mol by the Kissinger method. These ion conducting membranes have conductivities up to 10(-6) S/cm at 30 degrees C under anhydrous conditions. They have potential to be used in CO2 separation applications as they exhibit CO2 permeability of 59-110 Barrer and CO2/N-2 selectivity of 25-48

Toward a Materials Genome Approach for Ionic Liquids: Synthesis Guided by <i>Ab Initio</i> Property Maps

The Materials Genome Approach (MGA) aims to accelerate development of new materials by incorporating computational and data-driven approaches to reduce the cost of identification of optimal structures for a given application. Here, we use the MGA to guide the synthesis of triazolium-based ionic liquids (ILs). Our approach involves an IL property-mapping tool, which merges combinatorial structure enumeration, descriptor-based structure representation and sampling, and property prediction using molecular simulations. The simulated properties such as density, diffusivity, and gas solubility obtained for a selected set of representative ILs were used to build neural network models and map properties for all enumerated species. Herein, a family of ILs based on ca. 200 000 triazolium-based cations paired with the bis­(trifluoromethanesulfonyl)­amide anion was investigated using our MGA. Fourteen representative ILs spreading the entire range of predicted properties were subsequently synthesized and then characterized confirming the predicted density, diffusivity, and CO₂ Henry’s Law coefficient. Moreover, the property (CO₂, CH₄, and N₂ solubility) trends associated with exchange of the bis­(trifluoromethanesulfonyl)­amide anion with one of 32 other anions were explored and quantified