Self-assembly of the imidazolium surfactant in aprotic ionic liquids. The anion effect of aprotic ionic liquids.

The structure of ionic liquids (ILs) has an influence on their physiochemical properties, determining their performance as self-assembly media. In this study, we focus on the anion effect of aprotic ionic liquids (AILs). The aggregation behaviours of the cationic surfactant 1-hexadecyl-3-methylimidazolium bromide (CmimBr) have been investigated in the imidazolium AILs with the 1-ethyl-3-methyl imidazolium cation and different anions, including nitrate, ethylsulfate, bis(trifluoromethylsulfonyl) imide and tetrafluoroborate.

Gelation behavior and supramolecular chirality of a BTA derivative in a deep eutectic solvent.

As novel solvents, deep eutectic solvents (DESs) are non-toxic, easily producible and biocompatible, which is attractive for eutectogel fabrication. In this work, a benzene 1,3,5-tricarboxamide (BTA) derivative (substituted by three hexanoic acid) was selected to prepare a supramolecular gel in a suitable DES composed of choline chloride and phenylacetic acid molecules. The obtained eutectogel exhibited higher stability than that produced in conventional solvents.

Self-assembly of an imidazolium surfactant in aprotic ionic liquids. 2. More than solvents.

As tailorable solvents, the physiochemical properties of ionic liquids can be tuned by the structure of ions. Herein, we investigate the structural effects of ILs on the self-assembly of surfactants. It has been confirmed that the cationic surfactant 1-hexadecyl-3-methylimidazolium bromide (CmimBr) can self-assemble into micellar and lamellar lyotropic liquid crystal phases in the aprotic ionic liquid (AIL) 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim]BF).

Self-assembled luminescent cholate gels induced by a europium ion in deep eutectic solvents.

Deep eutectic solvents (DESs) with excellent physicochemical properties similar to ionic liquids and biocompatibility are potential solvent candidates for designing novel lanthanide luminescent soft materials. In this paper, the fabrication and characterization of such luminescent gels in three choline chloride (ChCl)-based DESs through self-assembly of the sodium cholate and europium nitrate are presented. The microstructure and gel-like nature of the obtained eutectogels were explored and confirmed by scanning electron microscopy and rheology measurements.

The self-assembly of an imidazolium surfactant in an aprotic ionic liquid. 1. Comparison in aprotic and protic ionic liquids.

The aggregation behaviour of a cationic surfactant in an aprotic ionic liquid has been explored. Prolate micelles are formed at low surfactant concentrations, while a lamellar lyotropic liquid crystal phase is formed at high surfactant concentrations.

Structural Study of Polystyrene--poly(acrylic acid) Micelles Complexed with Uranyl: A SAXS Core-Shell Model Analysis.

The interactions between natural colloidal organic matter and actinides in solutions are complex and not fully understood. In this work, a crew-cut polystyrene--poly(acry1ic acid) (PS--PAA) micelle is proposed as a model particle for humic acid (HA) colloid with the aim to better understand the sequestration, aggregation, and mobility of HA colloids in the presence of uranyl ions. The effects of uranyl ions on the structure of PS--PAA micelles in aqueous solution were mainly investigated by synchrotron small-angle X-ray scattering.

Investigation of Cu doped flake-NiO as an anode material for lithium ion batteries.

Cu foil is widely used in commercial lithium ion batteries as the current collector of anode materials with excellent conductivity and stability. In this research, commercial Cu foil was chosen as the current collector and substrate for the synthesis of Cu doped flake-NiO a traditional hydrothermal method. The effect of the ratio of Cu and the calcination temperature on the electrochemical performance of NiO was investigated.

Luminescent Sodium Deoxycholate Ionogel Induced by Eu in Ethylammonium Nitrate.

Hydrogels based on bile salts and lanthanide ions have been reported for their easy gelation. However, the weak mechanical properties and water quenching to luminescence of lanthanide ions limit their applications in practice. Hence, a supramolecular ionogel has been prepared here through simply mixing of sodium deoxycholate and europium nitrate in a protic ionic liquid, ethylammonium nitrate (EAN).

Molecular packing of surface active ionic liquids in a deep eutectic solvent: a small angle X-ray scattering (SAXS) study.

During the past decade, deep eutectic solvents (DESs) have shown promising application in the self-assembly of surfactants. Various aggregates such as micelles, vesicles, lyotropic liquid crystals, microemulsions and gels have been reported. In this research, the phase behaviours of imidazolium surface active ionic liquids (SAILs) CnmimBr (n = 12, 14, 16) were investigated in ChG.

Enhanced full color tunable luminescent lyotropic liquid crystals from P123 and ionic liquid by doping lanthanide complexes and AIEgen.

Hypothesis: The soft materials from ionic liquid mediated lyotropic liquid crystals (LLCs) containing europium complexes have exhibited enhanced luminescence efficiencies and photo-stabilities. The combination with aggregation-induced emissive compounds (AIEgens), however, may produce multicolor and even white emitting LLCs.

Experiments: Here, we have fabricated highly luminescent hexagonal (H) LLC containing a red-emitting trisdipicolinate lanthanide complex [choline][Eu(DPA)] (Eu-DPA) from Pluronic 123 and 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF).

Phase behaviours of a cationic surfactant in deep eutectic solvents: from micelles to lyotropic liquid crystals.

In recent years, aggregates formed in deep eutectic solvents (DESs), especially micelles, have attracted much attention. In this study, the phase behaviours of a cationic surfactant, cetylpyridinium bromide (CPBr), in two DESs, choline chloride + glycerol (ChG) and choline chloride + ethylene glycol (ChEG), were investigated in wide concentration and temperature ranges. With the help of small angle X-ray scattering, polarized optical microscopy and rheological measurements, the structures and properties of various aggregates were characterized.

(Ce-Al)-oxide pillared bentonite: A high affinity sorbent for plutonium.

The ability of bentonite and montmorillonite pillared by Al-oxide and mixed (Ln-Al)-oxides (Ln = La, Ce) to remove plutonium solution species from water is comparatively investigated at pH 7 and pH 4. Small-angle scattering and neutron contrast variation with HO/DO mixtures is used to verify the ingress of water in the calcined products after hydrophilicity was introduced by an NH-HO vapor treatment. The size and shape of the (La/Ce)-Al oxo-hydroxy pillaring cations (2 nm spheres) is determined by small-angle x-ray scattering from the pillaring solutions.

Unusual Aggregation Arrangement of Eu-Containing Polyoxometalate Hybrid in a Protic Ionic Liquid with Improved Luminescence Property.

Hybridization of polyoxometalates (POMs) with cationic surfactants offers the opportunity to greatly improve their functionalities as well as processabilities. Here, a surfactant-encapsulated Eu-containing POM complex (SEP) was formed via electrostatic interaction between 1-octadecyl-3-methylimidazolium bromide (OB) and Na(EuWO)·32HO (EuW). SEP was first self-assembled in a protic ionic liquid to prepare the soft aggregates to fundamentally avoid the fluorescence quenching by water molecules.

Visible-light/temperature dual-responsive hydrogel constructed by α-cyclodextrin and an azobenzene linked surfactant.

A novel photo-responsive anionic surfactant with a dimethylamino-substituted azobenzene located at the end of the hydrophobic chain, 6-(4-dimethylaminoazobenzene-4'-oxy)hexanoate sodium (DAH), has been designed. Through the host-guest interaction in aqueous solution, the trans-DAH could be spontaneously included by using two native α-cyclodextrin (α-CD) molecules. The formed hydrophilic inclusion complex (DAH@2α-CD), however, could act as a gelator to induce the formation of a supramolecular hydrogel, which is driven mainly by hydrogen bonds between neighboring α-CDs and also between the carboxylate in DAH and water.

Effects of a Spacer on the Phase Behavior of Gemini Surfactants in Ethanolammonium Nitrate.

The aggregation behavior of quaternary ammonium gemini surfactants (12-s-12) in a protic ionic liquid, ethanolammonium nitrate (EOAN), was investigated by small-angle X-ray scattering, freeze-fracture transmission electron microscopy, polarized optical microscopy, and rheological measurements. The rarely reported nonaqueous two phases in the ionic liquid were observed at lower 12-s-12 concentrations. The upper phase was composed of micelles, whereas only the surfactant unimers or multimers were detected in the low phase.

β-Cyclodextrin induced hierarchical self-assembly of a cationic surfactant bearing an adamantane end group in aqueous solution.

A cationic surfactant with adamantane as the end group, 1-[11-((adamantane-1-carbonyl)oxy)-undecyl]pyridinium bromide (AP), has been synthesized. Its β-cyclodextrin (β-CD) induced hierarchical self-assembling behaviors in aqueous solution were investigated using transmission or scanning electron microscopy methods and small-angle X-ray scattering measurements. Like conventional single chain surfactants, micelles could be formed by AP itself in dilute solutions.

Unique Phase Behaviors in the Gemini Surfactant/EAN Binary System: The Role of the Hydroxyl Group.

The hydroxyl group in the spacer of a cationic Gemini surfactant (12-3OH-12) caused dramatic changes of the phase behaviors in a protic ionic liquid (EAN). Here, the effects of the hydroxyl group on micellization and lyotropic liquid crystal formation were investigated through the surface tension, small-angle X-ray scattering, polarized optical microscopy, and rheological measurements. With the hydroxyl group in the spacer, the critical micellization concentration of 12-3OH-12 was found to be lower than that of the homologue without hydroxyl (12-3-12) and the 12-3OH-12 molecules packed more densely at the air/EAN interface.

Reverse lyotropic liquid crystals from europium nitrate and P123 with enhanced luminescence efficiency.

Fabrication of lyotropic aggregates containing the lanthanide ions is becoming a preferable way to prepare novel functional materials. Here, the lyotropic liquid crystals (LLCs) of reverse hexagonal, reverse bicontinuous cubic, and lamellar phases have been constructed in sequence directly from the mixtures of Eu(NO3)3·6H2O and Pluronic P123 amphiphilc block copolymer with increasing the salt proportion. Their phase types and structural characteristics were analyzed using polarized optical microscopy (POM) and small-angle X-ray scattering (SAXS) measurements.

Phase transition of a quaternary ammonium Gemini surfactant induced by minor structural changes of protic ionic liquids.

The aggregation behaviors of a Gemini surfactant [C12H25(CH3)2N(+)(CH2)2N(+)(CH3)2C12H25]Br2(-) (12-2-12) in two protic ionic liquids (PILs), propylammonium nitrate (PAN) and butylammonium nitrate (BAN), were investigated by means of several experimental techniques including small and wide-angle X-ray scattering, the polarized optical microscopy and the rheological measurement. Compared to those in ethylammonium nitrate (EAN), the minor structural changes with only one or two methylene units (-CH2-) increase in cationic chain length of PIL, result in a dramatic phase transition of formed aggregates. The critical micellization concentration was increased in PAN, while no micelle formation was detected in BAN.

Wormlike micelles formed using Gemini surfactants with quaternary hydroxyethyl methylammonium headgroups.

The aggregation behavior of Gemini surfactants with hydroxyl groups in their headgroups, butane-1,4-bis(hydroxyethyl methylalkylammonium) bromides hereafter abbreviated as m-4-m MEA (m = 12, 14, 16), has been investigated in aqueous solution. Each formed a viscous fluid in water at low concentration in the absence of a salt. In solutions of 14-4-14 MEA, the formation of highly viscoelastic wormlike micelles could be detected using steady and dynamic rheological measurements.

Lyotropic liquid crystalline phases of a phytosterol ethoxylate in amide solvents.

Materials exhibiting unique aggregation behavior in nonaqueous solvents have attracted attention due to their wide applications. Motivated by this recent interest, the aggregation properties of a phytosterol ethoxylate surfactant, BPS-10, in three organic amide compounds, formamide (FA), N-methylformamide (NMF), and N,N-dimethyl- formamide (DMF), have been studied. Polarized optical microscopy and small-angle X-ray scattering techniques were used to investigate the lyotropic liquid crystalline (LLC) phases formed in these binary systems.

Effects of structure dissymmetry on aggregation behaviors of quaternary ammonium Gemini surfactants in a protic ionic liquid EAN.

The aggregation behaviors of a series of dissymmetric cationic Gemini surfactants, [C(m)H(2m+1)(CH(3))(2)N(CH(2))(2)N(CH(3))(2)C(n)H(2n+1)]Br(2), designated as m-2-n (with a fixed m + n = 24, m = 16, 14, 12) have been investigated in a protic ionic liquid, ethylammonium nitrate (EAN). Surface tension, polarized optical microscopy (POM), small-angle X-ray scattering (SAXS), and rheological measurements are adopted to investigate the micellization and lyotropic liquid crystal (LLC) formation. The obtained results indicate that the structure dissymmetry plays an important role in aggregation process of m-2-n.

Comparison of aggregation behaviors of a phytosterol ethoxylate surfactant in protic and aprotic ionic liquids.

Two different room-temperature ionic liquids (ILs), the protic ethylammonium nitrate (EAN) and the aprotic 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF(4)), have been employed to investigate the solvent protonation effect on aggregation behaviors of a phytosterol ethoxylate surfactant (BPS-10). The calculated thermodynamic parameters based on surface tension measurements present a stronger solvophobic interaction in EAN than that in [Bmim]BF(4) and disclose different driving forces for micelle formation. In addition, the polarized optical microscopy and small-angle X-ray scattering techniques are used to characterize the phase structures formed in both systems at 25 °C.