Synthesis and physical properties of new surfactants based on ionic liquids: Improvement of thermal stability and mechanical behaviour of high density polyethylene nanocomposites

Ionic liquids based on alkyltriphenyl phosphonium and dialkyl imidazolium cations with long alkyl chains have been synthesized and used as new surfactants for cationic exchange of layered silicates. The influence of the alkyl chain length and the chemical nature of the conteranion or of the cation on the thermal stability of these new intercalating agents and on imidazolium- (MMT-I) or phosphonium- (MMT-P) modified montmorillonites have been analyzed by thermogravimetric analysis (TGA). Thermoplastic nanocomposites based on these modified montmorillonites with a very low amount of nanofillers (1wt.%) have been processed by melt mixing using a twin screw extruder. The distribution of the clay layers in a high density polyethylene (HDPE) matrix was characterized and finally the mechanical and thermal properties of the corresponding nanocomposites were determined.     

Surface properties of Gemini surfactants with pyrrolidinium head groups

This work is focused on the tailoring of dispersions of layered silicates, such as MICA SOMASIF (ME-100) within a fluoride matrix (polytetrafluoroethylene) through two strategies: the physicochemical interactions between filler and matrix and the processing of materials. The interactions in these complex systems are modified by new environmentally friendly thermally stable surfactants. The ionic liquids used are based on alkyltriphenyl phosphonium and perfluorinated alkylpyridinium cations. The influences of the cation-anion combination and functionalization were investigated. The use of the supercritical carbon dioxide (ScCO(2)) as a solvent is relevant to generate structuring within the material based on ionic liquid phase separation. The tunability of ionic liquids and their combination with the supercritical carbon dioxide enables to design materials with optimized thermal and mechanical properties.     

Anion effects on gas solubility in ionic liquids

This work presents the results of solubility measurements for a series of gases in 1-n-butyl-3-methyl imidazolium tetrafluoroborate and 1-n-butyl-3-methyl imidazolium bis(trifluoromethylsulfonyl) imide. The gases considered include benzene, carbon dioxide, nitrous oxide, ethylene, ethane, oxygen, and carbon monoxide. Carbon dioxide and oxygen solubilities are also reported in methyl-tributylammonium bis(trifluoromethylsulfonyl) imide, butyl-methyl pyrrolidinium bis(trifluoromethylsulfonyl) imide, and tri-isobutyl-methyl phosphonium p-toluenesulfonate. We report the associated Henry's constants and enthalpies and entropies of absorption. In general, benzene, followed by carbon dioxide and nitrous oxide, have the highest solubilities and strongest interactions with the ionic liquids, followed by ethylene and ethane. Oxygen had very low solubilities and weak interactions. Carbon monoxide had a solubility below the detection limit of our apparatus. Ionic liquids with the bis(trifluoromethylsulfonyl) imide anion had the largest affinity for CO(2), regardless of whether the cation was imidazolium, pyrrolidinium, or tetraalkylammonium. These results suggest that the nature of the anion has the most significant influence on the gas solubilities.     

New solid extractants for preconcentrating noble metals

New solid extractants are synthesized with the use of imidazolium and phosphonium ionic liquids for preconcentrating noble metals. Ionic liquids are selected and conditions for their immobilization on various solid matrices are found. The adsorption properties of the synthesized solid extractants for platinum(IV) in hydrochloric acid solutions are studied. The solid extractants obtained by binding 1-hexadecyl-3-methylimidazolium bromide and trihexyltetradecylphosphonium chloride to polymeric matrices and multiwall carbon nanotubes possess good kinetic properties and selectivity in 1 M HCl, and can be used to preconcentrate Pt(IV), Pd(II), and Au(III) in combined methods of their determination.     

Exploration of 4,5-dimethyl-1H-imidazole N-oxide derivatives in the synthesis of new achiral and chiral ionic liquids

New 1-alkoxy-3-alkyl-4,5-dimethylimidazolium bromides were synthesized by alkylation of the corresponding 1-alkylimidazole 3-oxides, which were conveniently prepared via condensation of α-(hydroxyimino)ketones, primary aliphatic amines, and formaldehyde. By using enantiomerically pure chiral amines, optically active imidazolium salts were obtained. Treatment with sodium tetrafluoroborate in acetone yielded the corresponding imidazolium tetrafluoroborates. All these compounds, with only one exception, were obtained as oils, which are considered as potential ionic liquids and ‘chiral ionic liquids’. The reduction of the chiral or non-chiral 1-alkylimidazole 3-oxides with Raney-Ni, followed by alkylation with alkyl bromides and subsequent ion exchange to tetrafluoroborates, gave the corresponding 1,3-dialkylimidazolium salts, most of them showing properties of ionic liquids. The alkylation of 1-butyl-4,5-dimethylimidazole 3-oxide and the corresponding imidazole, respectively, with 1,3-dibromopropane led to the first bis-imidazolium dibromides and bis-tetrafluoroborates.     

Cationic polymerization of styrene involving ionization of the C?Cl bond in ionic liquid/SO2 mixture

There has been a recent upsurge in interest in use of ionic liquids as reaction media for various chemical processes. Until recently, ionic liquids were considered as highly polar solvents. Our earlier investigation indicated that cationic polymerization of styrene initiated by aryl (alkyl) chlorides in ionic liquids may proceed even in the absence of coinitiator (Lewis acid). Polymerization, however, did not conform to controlled polymerization scheme. More recently, it has been claimed that ionic liquids are not as polar as it was previously assumed. Independently, high solubility of sulfur dioxide in ionic liquids was noticed. As sulfur dioxide displays a high ionizing power toward organic halides, we applied ionic liquid/sulfur dioxide mixture as a solvent in cationic polymerization of styrene initiated by aryl (alkyl) chlorides. Results show that in this reaction medium ionization of the C? Cl bond is facilitated, and the contribution of chain transfer reaction can be reduced as compared with polymerization in ionic liquid alone. Ionization of the C? Cl bond, however, is still not sufficiently fast to ensure conditions of controlled polymerization. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5251–5257, 2009     

烷基咪唑螯合硼离子液体的合成及摩擦学性能

以1种环境友好的双水杨酸螯合硼为阴离子中心,以咪唑环为阳离子骨架,合成了7种新的具有不同烷基直链的螯合硼离子液体D-C_nImBScB(n=4,6,8,10)和C_nImC8BScB(n=4,6,10).利用核磁共振波谱(~1H NMR)、热重分析(TGA)和差示扫描热量(DSC)等技术对7种双咪唑螯合硼离子液体进行了结构和热稳定性分析.以聚乙二醇(PEG200)作为基础油,双边咪唑螯合硼离子液体D-C_nImBScB(n=4,6,8,10)和C_nImC8BScB(n=4,6,10)作为添加剂,采用四球摩擦磨损试验机、扫描电子显微镜(SEM)和能量色散X射线光谱仪(EDX)分别对油样的抗磨减摩性能、磨斑形貌和磨斑表面元素分布进行了分析表征.结果表明,D-C_nImBScB(n=4,6,8,10)和C_nImC_8BScB(n=4,6,10)可用作在较宽温度范围使用的润滑油添加剂,添加C_6ImC_8BScB的PEG200油样抗磨效果最佳,其磨斑直径为0.712 mm,与PEG200相比降低了27.49%,通过适当调节阳离子咪唑环骨架上的双边烷基链长度可以调控离子液体的摩擦学性能.     

季膦-磷钨酸室温离子液体的合成及光催化降解罗丹明B

以不同摩尔比的磷钨酸与烷基取代季膦盐为原料合成了一系列磷钨酸类离子液体,并使用DSC和IR对系列离子液体进行了表征。 结果表明,[P(C14H29)(C6H13)3]-磷钨酸系列离子液体为室温离子液体,磷钨酸根保留了Keggin结构。 进一步研究了在可见光照射下,以所制备的磷钨酸季膦盐离子液体为催化剂催化降解罗丹明B染液。 以脱色率和COD来表征染料的降解效果,分别探讨了离子液体中阳离子碳链长度、催化剂用量、光照时间和罗丹明B的初始浓度等因素对光降解罗丹明B的影响。 结果表明,其中[P(C14H29)(C6H13)3]3-PW12O40离子液体的催化效果最好,在催化剂用量为0.3 g时,3 h内50 mL 8.35×10-5 mol/L罗丹明B的降解率可达到95%以上,催化剂重复使用5次后,脱色率仍可达到97%以上。     

Design of ionic liquids as a medium for the Grignard reaction

Design of novel phosphonium ionic liquids that are compatible with Grignard reagents have been investigated; several types of phosphonium salts that have an alkyl ether moiety have been synthesized and their capability evaluated as solvents for Grignard reagents. It has been established that even basic aliphatic Grignard reagent-mediated reactions are possible when methoxyethyl(tri-n-butyl)phosphonium bis(trifluoromethanesulfonyl)imide is used as the solvent.     

咪唑基离子液体固定分离CO2的研究进展

以咪唑基离子液体为代表,综述了近期普通咪唑基离子液体、功能咪唑基离子液体、支撑咪唑基离子液体和聚合咪唑基离子液体在分离固定CO2方面的研究进展,说明了各类咪唑基离子液体分离固定CO2的可行性及优缺点,并总结了离子液体固定CO2的影响因素和分离机制.     

Carbon-centered strong bases in phosphonium ionic liquids

Phosphonium ionic liquids (PhosILs), most notably tetradecyl(trihexyl)phosphonium decanoate (PhosIL-C(9)H(1)9COO), are solvents for bases such as Grignard reagents, isocyanides, Wittig reagents (phosphoranes), and N-heterocyclic carbenes (NHCs). The stability of the organometallic species in PhosIL solution is anion dependent. Small bases, such as hydroxide, react with the phosphonium ions and promote C-H exchange as suggested by deuterium-labeling studies. A method to dry and purify the ionic liquids is described and this step is important for the successful use of basic reagents in PhosIL. NHCs have been generated in PhosIL, and these persistent solutions catalyze organic transformations such as the benzoin condensation and the Kumada-Corriu cross-coupling reaction. Phosphoranes were generated in PhosIL, and their reactivity with various organic reagents was also tested. Inter-ion contacts involving tetraalkylphosphonium ions have been assessed, and the crystal structure of [(n-C(4)H(90)(4)P][CH(3)CO(2).CH(3)CO(2)H] has been determined to aid the discussion. Decomposition of organometallic compounds may also proceed through electron-transfer processes that, inter alia, may lead to decomposition of the IL, and hence the electrochemistry of some representative phosphonium and imidazolium ions has been studied. A radical derived from the electrochemical reduction of an imidazolium ion has been characterized by electron paramagnetic resonance spectroscopy.     

Molecularly imprinted SPE coupled with HPLC for the selective separation and enrichment of alkyl imidazolium ionic liquids in environmental water samples

A novel 1‐butyl‐3‐methylimidazolium chloride ionic liquid surface imprinted solid‐phase sorbent was synthesized. The as‐prepared material was characterized by SEM, Brunauer–Emmett–Teller surface area analysis and Fourier Transform IR measurements. Then its adsorption properties for alkyl imidazolium ionic liquids, including adsorption capacities, adsorption kinetics, and properties of selective separation and enrichment were studied in detail. It was shown that the ionic liquid surface imprinted polymer exhibited high selective recognition characteristics for the imidazolium chloride ionic liquids with short alkyl chains (C_nmimCl, n = 2, 4, 6, 8) and the adsorption equilibrium was achieved within 25 min. Various parameters were optimized for the 1‐butyl‐3‐methylimidazolium chloride ionic liquid surface imprinted polymer SPE column, such as flow rate, eluent solvent, selectivity, and reusability of the column. Then, the SPE column coupled with HPLC was used for the determination of alkyl imidazolium ionic liquids. Experimental results showed that the existence of their structural analogs and common concomitants in environmental matrices did not affect the enrichment of 1‐butyl‐3‐methyl imidazolium chloride ionic liquid. The average recoveries of 1‐butyl‐3‐methylimidazolium chloride ionic liquid in spiked water samples were in the range of 92.0–102.0% with the RSD lower than 5.8%.     

Synthesis of Low‐Viscosity Ionic Liquids for Application in Dye‐Sensitized Solar Cells

Two types of ionic liquids (ILs), 1‐(3‐hexenyl)‐3‐methyl imidazolium iodide and 1‐(3‐butenyl)‐3‐methyl imidazolium iodide, are synthesized by introducing an unsaturated bond into the side alkyl chain of the imidazolium cation. These new ionic liquids exhibit high thermal stability and low viscosity (104 cP and 80 cP, respectively). The molecular dynamics simulation shows that the double bond introduced in the alkane chain greatly changes the molecular system space arrangement and diminishes the packing efficiency, leading to low viscosity. The low viscosity of the synthesized ionic liquids would enhance the diffusion of redox couples. This enhancement is detected by fabricating dye‐sensitized solar cells (DSSCs) with electrolytes containing the two ILs and I₂. The highest efficiency of DSSCs is 6.85 % for 1‐(3‐hexenyl)‐3‐methyl imidazolium iodide and 5.93 % for 1‐(3‐butenyl)‐3‐methyl imidazolium iodide electrolyte, which is much higher than that of 5.17 % with the counterpart 1‐hexyl‐3‐methyl imidazolium iodide electrolyte.     

Synthesis and Physical Properties of Tunable Aryl Alkyl Ionic Liquids (TAAILs)

Tunable aryl alkyl ionic liquids (TAAILs) based on the imidazolium cation were first reported in 2009. Since then, a series of TAAILs with different properties due to the electron-donating or -withdrawing effect of the substituents at the aryl ring has been developed. Herein, a wide variety of those ionic liquids (ILs) is presented in terms of their cation structure. The authors synthesized ILs containing the bromide or bis(trifluoromethane)sulfonimide anion and 1-aryl-3-alkyl imidazolium cations with various substituents in the ortho and/ or para position of the phenyl ring and alkyl chains of different lengths varying from butyl to dodecyl. The differences of their physical properties (melting point, thermal decomposition, viscosity, electro-chemical window) of these ILs are reported according to their structure.     

Synthesis and characterization of novel chiral imidazolium and pyridinium ionic liquids derived from tartaric acid and 2-oxazolidinone

Abstract

Novel chiral imidazolium and pyridinium ionic liquids based on tartaric acid and 2-oxazolidinone were designed. Symmetrical dicationic ionic liquids based on tartaric acid have been synthesized and characterized. These chiral ionic liquids were designed by employing very short and simple methods. Incorporation of alkyl halide over tartaric acid and 2-oxazolidinone is an important step. N-methyl imidazole and pyridine were used for preparation of quaternary salts. These ionic liquids have been evaluated for the asymmetric sulfide oxidation. Chiral ionic liquids based on tartaric acid showed superior chiral inducing property as compare to 2-oxazolidinone based chiral ionic liquids.     

Tailoring of interfacial properties by ionic liquids in a fluorinated matrix based nanocomposites

Different ionic liquids based on alkyltriphenylphosphonium and imidazolium-functionalized either with two alkyl chains or with a fluorinated chain have been synthesized and used as interfacial agents for the layered silicates. The effect of the chemical nature of the organic cation on the morphology and the physical properties of the polyvinylidene fluoride (PVDF) nanocomposites has been studied. The influence of ionic liquids on polymorphic crystalline forms, i.e. α and β phases of the polymer matrix was discussed.     

Thermal decomposition of various alkyl onium organoclays: Effect on polyethylene terephthalate nanocomposites' properties

The thermal stability of organically modified layered silicates is determinant for processing polymer nanocomposites and is believed to play a key role on their properties. In this work, alkyl phosphonium, alkyl pyridinium and dialkyl imidazolium surfactants were used as intercalating agents for the preparation of highly thermally stable organophilic montmorillonites. The thermal decomposition of the surfactants and of their organoclays was studied by combined thermogravimetric analysis (TGA) and mass spectroscopy (MS), which allowed the identification of specific volatile compounds issued from the degradation. In order to investigate the influence of the thermal decomposition of the intercalating agent during processing, the various organoclays were incorporated in a polyethylene terephthalate (PET) matrix. The color of the nanocomposites was significantly affected by the thermal decomposition of the intercalating agent. In the case of the alkyl pyridinium modified clay, the degradation of the intercalating agent during processing was found to alter the clay dispersion. Finally, the crystallization was analyzed by differential scanning calorimetric (DSC) analysis and polarized optical microscopy (POM): it was demonstrated that the kinetics of nucleation and growth is not only affected by the dispersion state of the clay, but also depends on the clay/polymer interface properties, and therefore on the nature of the intercalating agent.     

Synthesis of chiral ionic liquids from natural amino acids

For the first time, chiral imidazolium ionic liquids containing one chiral carbon (10a-c) were synthesized from the natural amino acids by a simple and straightforward procedure. The characteristics of the chiral ILs are very similar to the popular ionic liquids.     

Acrylate functionalized tetraalkylammonium salts with ionic liquid properties

Acrylate functionalized ionic liquids based on tetraalkylammonium salts with terminal acrylates- and methylacrylates were synthesized. Melting points and ionic conductivity of twenty compounds in six groups were determined. Within one group the effect of three different counterions was investigated and discussed. The groups differ in cationic structure elements because of their functional groups such as acrylate and methacrylate, alkyl residues at the nitrogen and number of quaternary ammonium atoms within the organic cation. The effect of these cationic structure elements has been examined concerning the compiled parameters with a view to qualifying them as components for solid state electrolytes. The newly synthesized ionic liquids were characterized by NMR and FTIR analysis. The exchange of halide ions like bromide as counter ions to weakly coordinating [PF?]?, [OTf]? or [TFSI]? reduces the melting points significantly and leads to an ion conductivity of about 10?? S/cm at room temperature. In the case of the dicationic ionic liquid, an ion conductivity of about 10?3 S/cm was observed.     

基于阳离子交换基团的阴离子交换膜研究进展

近年来,阴离子交换膜燃料电池的发展受到了广泛关注。 开发具有碱稳定性能优异、电导率高的阴离子交换膜材料成为了研究的热点。 阴离子交换膜(AEM)主要由聚合物骨架和阳离子基团组成,除了聚合物骨架结构,离子交换基团是影响膜碱稳定性和电导率的重要因素,因此,设计离子基团是提高膜性能的重要手段之一。 本文综述了近年来功能基团分别为季铵、胍基、咪唑鎓盐、季鏻、金属配合物、N-螺环季铵盐、哌啶和吡咯等阳离子交换基团的AEM的研究进展,其中包括不同种类阳离子交换基团的AEM的结构,碱稳定性能和OH^-电导率,同时对于含有阳离子交换基团的AEM的结构设计进行了分析和展望。