Functional thiol ionic liquids as novel interfacial modifiers in SBR/HNTs composites

Two kinds of thiol ionic liquids (ILs), 1-methylimidazolium mercaptopropionate (MimMP) and bis (1-methylimidazolium) mercaptosuccinate (BMimMS), were investigated as novel interfacial modifiers for styrene butadiene rubber/halloysite nanotubes (SBR/HNTs) composites. According to model compounds, it was found that their affinities toward HNTs were originated from hydrogen bonding and that they could be grafted onto SBR chains via thiol-ene reactions. The ILs addition could promote vulcanization and effectively facilitate HNTs dispersion in rubber matrix. The interfacial interaction, quantitatively evaluated by a proposed equation based on rubber elasticity and reinforcement theory, was consistently increased. Mechanical properties of SBR/HNTs vulcanizates were largely improved and better than those of the 3-mercaptopropyl trimethoxysilane modified system. The BMimMS’s efficiency on modifying SBR/HNTs vulcanizates was higher than the other for its Gemini structure. Significantly mechanical improvements and lowered mechanical loss in the range of 50-80 °C were correlated to the improved HNTs dispersion and strengthened interfacial interactions.     

Polymer electrolytes based on poly(ethylene glycol) dimethyl ether and the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate: Preparation, physico-chemical characterization, and theoretical study

Polymer electrolytes based on poly(ethylene glycol) dimethyl ether (PEGdME) and the ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF₆) have been prepared and characterized by different techniques. Coordination of the IL by the polymer occurs mainly in the amorphous phase. This finding was correlated with previous theoretical investigations of a similar model for polymer electrolytes based on poly(ethylene oxide), PEO, and IL. It has been obtained ionic conductivity σ ∼ 10⁻³ S cm⁻¹ for the polymer electrolyte with 35 wt% of IL at 100 °C. The same order of magnitude for σ was obtained by molecular dynamics simulation of PEO/IL. This work demonstrates consistency between experimental and theoretical results for polymer electrolytes containing ionic liquids.     

分子模拟评价离子液体作为萃取精馏中萃取剂

探索性地使用分子模拟软件Material Studio计算二元物系中溶剂分子(离子液体)与溶质分子间的混合能,并以两者的混合能差值评价萃取剂的优劣。计算了离子液体与溶质的二元物系的混合能差,并用文献中的无限稀释活度系数,得到选择性Ss以验证模拟计算结果。结果表明选择性与混合能差值之间有一定规律可循,为进一步深入研究打下基础。     

Selective Separation of Toluene/n‐Heptane by Supported Ionic Liquid Membranes with [Bmim][BF4]

Room‐temperature ionic liquids serve as alternative solvents for volatile organic compounds in liquid‐liquid extraction and liquid membrane separation. 1‐Butyl‐3‐methylimidazolium tetrafluoroborate ([Bmim][BF₄]) was applied for extraction and supported ionic liquid membranes (SILMs) to separate toluene and n‐heptane. A high separation factor of toluene was achieved due to the strong interaction between ionic liquid cations and toluene. The mass transfer performance of the SILM process was enhanced by higher operating temperature. With the increase of initial toluene concentration in the feed phase, the mass transfer flux and removal efficiency of the SILM process were improved, while the separation factor decreased. The mass transfer flux was growing with the increase of flow rate at both sides. The SILM process was stable over a long time period due to the high viscosity and low volatility of [Bmim][BF₄].     

Shape of Long Chain Alkyl Sulfonate Micelle upon Salt Addition: a Molecular Dynamics Study

Here we report a molecular dynamics simulation on the state of long chain alkyl sulfonate micelle which occurs in the presence of salt. We tracked the formation of a large micelle with a dumbbell‐like shape, which has hemispherical end caps with a large radius rather than the middle cylindrical body, where the shape bending angle was around 160^o. The data from chain analysis indicate that the micelle hydrocarbon layer is covered with disordered tails. We also report micelle fission controlled by changes in salt concentration. Overall, the parameters obtained are compared with existing experimental findings.     

离聚体的结构及其影响因素

离聚体中的离子对具有一定的配位结构,由于离子对的聚集作用能形成多重离子对或离子簇结构;离子对含量、离子对的特性、聚合物基质的性质、增塑剂、吸收的水份及热作用等都将影响离聚体的结构.本文对这些内容进行了综述.     

Ionothermal synthesis of gallophosphate molecular sieves in 1-alkyl-3-methyl imidazolium bromide ionic liquids

Gallophosphate (GaPO₄) molecular sieves were ionothermally prepared in 1-alkyl-3-methyl imidazolium bromide ionic liquids (ILs) with alkyl chain length varying from 2 to 6 carbons for the first time. Three kinds of GaPO₄ materials such as GaPO₄-a, cloverite (denoted as CLO below) and GaPO₄-LTA were obtained, and their structures and morphologies were characterized by powder and single crystal XRD, SEM and multi-nuclear NMR. In the case of 1-ethyl-3-methyl imidazolium bromide ionic liquid, large single crystals of GaPO₄-LTA with well-defined octahedral morphology was obtained in both sealed (ca. 400 μm in size) and open vessels (ca. 300 μm in size). Ionothermal synthesis is an effective method for the preparation of large single crystal of molecular sieves. With the alkyl chain length of the ionic liquids increasing from 2 carbons to 6 carbons, the size of GaPO₄-LTA decreased sharply. The organic template cations in the as-synthesized GaPO₄-LTA crystals may have two different kinds of conformational structures. Fluorine plays a role of co-template along with organic cations of ILs in the synthesis of GaPO₄-LTA and CLO, while only GaPO₄-a was obtained in the absence of fluorine. The reaction temperature can also affect the structure of the final structure. In the reaction medium of 1-ethyl-3-methyl imidazolium bromide IL, GaPO₄-LTA was obtained at 180 °C, while CLO was obtained at 150 °C.     

Improved ionic conductivity of nitrile rubber/ionic liquid composites

Polymer electrolytes with high ionic conductivity and good elasticity were prepared by mixing nitrile rubber (poly(acrylonitrile-co-butadiene) rubber; NBR) with ionic liquid, N-ethylimidazolium bis(trifluoromethanesulfonyl)imide (EImTFSI). The NBR/EImTFSI composites were obtained as homogeneous and transparent films when the ionic liquid content was less than 60 wt%. Raman spectroscopy suggested the interaction between nitrile group of NBR and TFSI anion. Sample with ionic liquid content of 50 wt% showed the ionic conductivity of 1.2×10⁻⁵ S cm⁻¹ at 30 °C. Addition of lithium salt to this NBR/EImTFSI composite further enhanced the ionic conductivity to about 10⁻⁴ S cm⁻¹ without spoiling mechanical properties. DSC studies showed two glass transition temperatures for composites indicating microphase separation.     

固载化离子液体制备方法的研究进展

近年来,集均相和非均相材料的优点于一身的固载化离子液体一直是化学家们研究的重点之一.本文概述了固载化离子液体制备方法的研究进展.     

Ionic conductivity of polymer gels deriving from alkali metal ionic liquids and negatively charged polyelectrolytes

We have prepared polymer gel electrolytes with alkali metal ionic liquids (AMILs) that inherently contain alkali metal ions. The AMIL consisted of sulfate anion, imidazolium cation, and alkali metal cation. AMILs were mixed directly with poly(3-sulfopropyl acrylate) lithium salt or poly(2-acrylamido-2-methylpropanesulfonic acid) lithium salt to form polymer gels. The ionic conductivity of these gels decreased with increasing polymer fraction, as in general ionic liquid/polymer mixed systems. At low polymer concentrations, these gels displayed excellent ionic conductivity of 10⁻⁴ to 10⁻³ S cm⁻¹ at room temperature. Gelation was found to cause little change in the diffusion coefficient of the ionic liquid, as measured by pulse-field-gradient NMR. These data strongly suggest that the lithium cation migrates in successive pathways provided by the ionic liquids.     

Molecular modeling studies of polymer electrolytes for power sources

Density functional theory and classical molecular dynamics simulations permit us to elucidate details of ionic and molecular transport useful for the design of polymer electrolyte membranes. We consider two systems of current interest: (a) ionic transport in polyethylene-oxide compared to that in a polyphosphazene membrane targeted to be a good ionic carrier but a bad water carrier and (b) transport of oxygen and protons through hydrated nafion in the vicinity of a catalyst phase.It is shown that in polyphosphazene membranes, nitrogen atoms interact more strongly with lithium ions than ether oxygens do. As a result of the different complexation of Li⁺ with the polymer sites, Li⁺ has a much higher diffusion coefficient in polyphosphazene than in polyethylene oxide electrolyte membranes, with the consequent relevance to lithium-water battery technology.For the hydrated membrane/catalyst interface, our simulations show that the Nafion membrane used in low-temperature fuel cells interacts strongly with the catalytic metal nanoparticles directing the side chain towards the catalyst surface. Results at various degrees of hydration of the membrane illustrate the formation of water clusters surrounding the polymer hydrophilic sites, and reveal how the connectivity of these clusters may determine the transport mechanism of protons and molecular species.     

SO2／离子液体体系热力学性质的分子动力学模拟

为研究SO2对咪唑类普通离子液体输运特性、体积的影响,本文通过分子动力学方法模拟了293．15K时,常压下[bmim][PFs]和[bmim][BF4]与soz的？昆合物。结果表明,咪唑类普通离子液体的扩散系数随气体溶质摩尔分数的增加而增大,粘度则相应减小。吸收SO2对离子液体体积的影响极小。混合物摩尔体积随SO2摩尔分数增加呈直线下降。     

Molecular dynamics simulations of CO2 permeation through ionic liquids confined in γ-alumina nanopores

CO₂ permeation through imidazolium-based ionic liquids (ILs, [BMIM][Ac], [EMIM][Ac], [OMIM][Ac], [BMIM][BF₄], and [BMIM][PF₆]) confined in 1.0, 2.0, and 3.5?nm γ-alumina pores was investigated using molecular dynamics simulation. It was found that the nanopore confinement effect influenced the structure of confined ILs greatly, resulting in a layered structure and anisotropic orientation of ILs. In the center of 2.0-nm pore, the long alkyl chain of [BMIM]⁺ tended to be parallel to the wall, providing a straight diffusion path benefiting the CO₂ permeation. The CO₂ diffusion coefficients in confined [EMIM][Ac], [BMIM][Ac], and [OMIM][Ac] were 2.3–4.1, 2.4–6.4, and 14.4–21.7?×?10^?10?m²?s^?1, respectively. This order was opposite to that in the bulk ILs, because the longer alkyl chain led to a more ordered structure, facilitating CO₂ diffusion. In addition, the CO₂ solubilities were 445–722?mol?m^?3?MPa^?1 for the five ILs confined in 1.0?nm pore, which were larger than those in 2.0 and 3.5?nm pores (196–335?mol·m^?3?MPa^?1), due to the larger free volume. Both parallel orientation of alkyl chain and large free volume could increase the CO₂ permeability in confined ILs.     

影响火炸药吸湿性因素的研究

火炸药在国防军事和工业生产中有着较为广泛的使用范围,研究火炸药的吸湿性对于火炸药的生产、储存有着极大的军事经济价值。分析火炸药的物理化学性质,进而探索其吸湿的原因,分析影响火炸药吸湿性的各种因素,并以此改善火炸药的生产、存储环境。     

Influence of subphase on the orientation of helical peptides at interface

Boc-(l-Leu-Aib)_n-OBzl (n=8, 12, 16; OBzl represents benzyl ester) was spread on water or a mixture of water and methanol (1/1 v/v) and the orientation of the helical peptides on subphase was investigated by FTIR-reflection-absorption spectroscopy. When the peptides were spread at a liquid phase on subphase, the peptides took a vertical orientation, which was not attainable by compression of peptide monolayers initially spread at a gas phase on subphase. However, the peptide monolayers on water could not be transferred on gold with keeping the vertical orientation. On the other hand, when the peptides were spread on a mixture of water and methanol, the orientation of helical peptides was closer to vertical than that on water and the monolayers were transferred repeatedly on gold to form multilayers with a vertical orientation. The suppression of orientation change upon transfer of the peptide monolayer is considered to be due to reduction of electrostatic interaction between the peptide and the image dipole when the peptide is spread on a mixture of water and methanol.     

Effect of cation structure on the electrochemical and thermal properties of ion conductive polymers obtained from polymerizable ionic liquids

Several onium cations having vinyl group formed ionic liquids after coupling with bis(trifluoromethanesulfonyl)imide. These monomers were polymerized, and the relation between onium cation structure and properties of thus polymerized ionic liquids was investigated. The polymerized ionic liquid having ethylimiadzolium cation unit showed the highest ionic conductivity of around 10⁻⁴ S cm⁻¹ at 30 °C among the obtained polymers reflecting the lowest glass transition temperature of −59 °C. These polymers were thermally stable and their decomposition temperatures were about 350 °C. The ionic conductivity of the polymerized ionic liquids decreased by both the addition of lithium bis(trifluoromethanesulfonyl)imide and the polymerization in the presence of cross-linker. However, the polymerized ionic liquid having 1-methylpiperidinium cation structure showed good lithium ion transference number of 0.43 at room temperature.     

SOLVENT EXTRACTION STUDIES ON LANTHANIDE ACETYLACETONATES,Part I. Promethium complexes investigated by the AKUFVE-LISOL technique.

Beginning with this paper a series of studies on lanthanide acetylacetonates (LnAa_n) will be presented. The solvent extraction technique is used to determine the equilibrium constants β_n for the succesive complex formation, where 1 ≤ n ≤. 4, in 1 M NaClO₄ at 25°C, the self adduct constants K_add1 for the formation of LnAa₃(HAa)_i species in the organic (benzene) phase and the two-phase distribution constant P₃ for the uncharged LnAa₃ complexes.

This paper will be more detailed than the succeeding ones. The background and purpose of the investigation is outlined. For the experiments the semiautomatic AKUFVE solvent-extraction technique is used in connection with a recently developed highly sensitive detection technique named LISOL.

The equilibrium constants obtained for the formation of the promethium acetylacetonate complexes in the aqueous phase are log β₁ 5.35, log β₂ 9.20, log β₃ 12.22 and log β₄ 14.06. The constants for the adduct formation in the benzene phase

LnAa₃(org) + iHAa (org)<= = =>LnAa₃(HAa)_i(org) (la)

are K_add1 ≈ 7 and K_add2 ≈ 3. The distribution constant P₃ for PmAa₃ (hydrated) between the two phases is ≈0.008. These latter values are fairly uncertain, but the product P₃ · K_add1 ≤ 0.12 is quite reliable.