Effect of alkyl chain on micellisation properties of dodecylsulphate based surface active ionic liquids in aqueous solutions using conductance and surface tension techniques (original) (raw)
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Journal of Dispersion Science and Technology, 2019
Two surface active ionic liquids (ILs) having 1-alkyl-3-methylimidazolium cationic moiety and dodecylbenzenesulfonate based anionic moiety i.e. [C 5 mim][DBS] and [C 7 mim][DBS], have been synthesized. 1 H-NMR, thin layer chromatography were done for their characterization. These DBS-ILs have lower critical micelle concentration (CMC) in comparison with their conventional sodium dodecylbenzenesulfonate [Na][DBS] surfactants and hence are highly surface active. The conductance, surface tension, absorption (UV-visible) and emission (Fluorescence) techniques were used to determine the CMC values. DBS-ILs showed a remarkable absorption and emission spectra where intensity changes with variation in concentration of IL. Micelle self-assembly formation was also predicted by dynamic light scattering (DLS) technique. Conductance and surface tension techniques were employed to study the aggregation behavior in aqueous conditions. Various surface active parameters were evaluated at 298.15 K employing surface tension techniques. Conductance measurements were performed at three rising temperatures (288.15, 298.15, and 308.15) K and their thermodynamic parameters were calculated. From the above studies, the present synthesized ionic liquids found to have remarkable surface activity.
Journal of Molecular Liquids, 2018
In this work the influence of cationic structure of surface active ionic liquids (SAILs) on their micellization process in water is investigated by isothermal titration calorimetry (ITC) at temperatures between 278.15 and 318.15 K. First, 1-dodecylimidazolium bromide ([C12im]Br) was studied, and then the length of alkyl chain on the N3 position is varied from methyl-(1dodecyl-3-methylimidazolium bromide ([C12mim]Br)), ethyl-(1-dodecyl-3-ethylimidazolium bromide , [C12eim]Br), to butyl-(1-dodecyl-3-butylimidazolium bromide, [C12bim]Br). In next step, the N3 was replaced by S atom in 3-dodecylthiazolium bromide ([C12thiaz]Br) as an analogue of [C12im]Br. Due to problems at synthesis and low solubility of other thiazolium analogues no further experiments on these systems were possible. ITC experimental data were analyzed by the help of an improved model, yielding simultaneously the values of critical micelle concentration, cmc and enthalpy, ∆MH θ by the fitting procedure together with the degree of counter ion binding, , aggregation number, n, standard heat capacity, ∆M and Gibbs free energy, ∆MG θ of micellization. It was found that the investigated systems behave mainly like common ionic surfactants and already investigated SAILs: the micellization process of investigated systems was detected as endothermic at low temperatures and exothermic at high temperatures; the values of cmc are decreasing with the increasing length of alkyl chain on N3 position. Between [C12thiaz] + and Brweaker interactions were found in comparison to those between [C12im] + and Brwhat can be ascribed to more expressed aromaticity of thiazolium ring. ∆M values were further discussed, regarding the removal of water molecules from contact with nonpolar surface area upon micelle formation. It can be concluded, that the ethyl-and butylchain on N3 position are folded during the micellization process and thus they are (at least) partially removed from contact with water.
Journal of Colloid and Interface Science, 2010
The complex formation between anionic polyelectrolyte poly(acrylic acid sodium salt) [NaPAA] and surface active ionic liquid (SAIL) lauryl isoquinolinium bromide [C 12 iQuin][Br] in aqueous media has been investigated by surface tension, isothermal titration calorimetry (ITC), and conductance. The self-assembled structures have been characterized using dynamic light scattering (DLS) and turbidity measurements. A range of surface parameters have been calculated from tensiometric measurements including critical micelle concentration (CMC), surface excess concentration (Γ cmc), surface pressure at the interface (Π cmc), minimum area occupied at air-solvent interface (A min), adsorption efficiency (pC 20), and surface tension at the CMC (γ cmc). The thermodynamic parameters, i.e., standard enthalpy of micellization ΔH m À Á , standard free energy of micellization (ΔG m), and standard entropy of micellization (ΔS m) have also been evaluated. Four different stages of transitions, corresponding to the progressive formation of NaPAA-[C 12 iQuin][Br] complex (C 1) , critical aggregation concentration (CAC), critical saturation concentration (C 3) and CMC have been observed owing to strong electrostatic and hydrophobic interactions. The results obtained from DLS and turbidity measurements show that size of the aggregates first decreases and then increases in the presence of polyelectrolyte. The binding isotherms obtained using isothermal titration calorimetry (ITC) show the concentration dependence as well as the highly cooperative nature of interactions corresponding to formation of polyelectrolyte-SAIL complexes.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2017
A systematic investigation of influence of the length of the side alkyl chain and the counter ions on the thermodynamic of the micellization process at imidazolium based surface active ionic liquids (SAILs) in aqueous solution was carried out by isothermal titration calorimetry (ITC) in a broad temperature range. The effect of alkyl chain length on the micellization process in water has been investigated on 1decyl-3-methylimidazolium ([C 10 mim]Cl) 1-dodecyl-3-methylimidazolium ([C 12 mim]Cl), 1tetradecyl-3-methylimidazolium ([C 14 mim]Cl) and 1-hexadecyl-3-methylimidazolium ([C 16 mim]Cl) chlorides, whereas the influence of counterion was studied at the micellization of 1-dodecyl-3-methylimidazolium chloride ([C 12 mim]Cl), bromide ([C 12 mim]Br), iodide ([C 12 mim]I), acetate ([C 12 mim]OAc), methanesulfonate ([C 12 mim]OMs), toluensulfonate (([C 12 mim]OTs), trifluromethane sulfonate ([C 12 mim]OTf), trifluoro acetate (([C 12 mim]TFA) and salicylate ([C 12 mim]Sal) in water.
Physical chemistry chemical physics : PCCP, 2014
Amide-functionalized surface active ionic liquids (SAILs), 1-methyl-1-dodecyl piperidinium chloride, [C12APip][Cl]; 1-methyl-1-dodecyl pyrrolidinium chloride, [C12APyrr][Cl]; 1-methyl-3-dodecyl imidazolium chloride, [C12Amim][Cl], and 1-methyl-1-dodecyl morpholinium chloride, [C12AMorph][Cl], have been synthesized, characterized and investigated for thermal stability, and micellization behavior in aqueous medium. The introduction of an amide moiety in the alkyl chain decreased the thermal stability of the functionalized SAILs compared to non-functionalized SAILs bearing a simple alkyl chain. A variety of state of the art techniques, viz. tensiometry, conductometry, steady-state fluorescence, isothermal titration calorimetry (ITC), dynamic light scattering (DLS) and atomic force microscopy (AFM), have been employed to investigate the micellization behavior. Amide-functionalized SAILs have shown much lower critical micelle concentration, cmc, and better surface active properties as co...
Interfacial and Aggregation Behaviour of Sodium Dodecyl Sulphate Induced by Ionic Liquids
Journal of oleo science, 2021
Aggregation studies of anionic surfactant sodium dodecyl sulphate (SDS) was investigated in aqueous 1-butyl-3-methylimidazolium chloride [bmim]Cl and N-butyl-N-methyl pyrrolidinium tetrafluoroborate [bmp]BF4 ionic liquid (IL) solutions respectively. Systems were studied by surface tension, conductance, UV-vis absorption/emission spectroscopy and dynamic light scattering. Critical micelle concentration (CMC) values gradually decreased with increasing IL concentration which indicates synergistic interaction between ILs and SDS. Gibbs free energy change results demonstrated spontaneous micellization induced by ILs; however the effect of ILs were not similar to the corresponding regular salts (NaCl and NaBF4). Aggregation number (n) of micelles, determined by fluorescence quenching method, indicate that the 'n' values increase with increasing ILs concentration, induced by the oppositely charged IL cation. Size of the micelles, determined by dynamic light scattering studies, incr...
The journal of Physical Chemistry B , 2014
The effect of four cationic ionic liquids (ILs), 1-butyl-3-methylimidazolium chloride (BMImCl), 1-butyl-3-methylimidazolium bromide (BMImBr), 1-hexyl-3-methylimidazolium chloride (HMImCl), and 1-hexyl-3-methyl-imidazolium bromide (HMImBr) on surface activity and micellization of an anionic surfactant, sodium dodecyl sulfate (SDS), is studied. The thermodynamic data on micellization and surface adsorption are obtained from tensiometry and conductometry. The applicability of UV–visible spectroscopy to study of SDS/IL systems is also investigated using Crystal Violet as the probe. Cyclic voltammetry, dynamic light scattering, and TEM imaging are employed to investigate the size and morphology of aggregates. According to the findings, addition of butyl-chained ILs to aqueous SDS results in only a slight gradual increase in average aggregate size whereas the size of SDS assemblies are dramatically increased upon addition of hexyl-chained ILs. It is proposed that BMIm+ cations of the IL undergo Coulombic attractive interactions with anionic headgroups adsorbed at the micellar surface in aqueous SDS whereas HMIm+ interact through hydrophobic chain–chain attractions as well. Thus, mixed micellization results in formation of vesicles. A micellar phase change from vesicles to micelles takes place at higher [SDS]/[IL] ratios. All of these processes are successfully tracked by the employed techniques.
Journal of Molecular Liquids, 2020
Ionic liquid (IL)-modified surfactant systems have versatile applications in several technological areas. Therefore, it is utmost need to achieve full understanding of interactions existing in such systems before their further uses. Here, the effects of IL, 1-ethyl-3-methylimidazolium hexafluorophospahte, [emim][PF 6 ] on the physicochemical properties of aqueous sodium dodecyl sulfate (SDS) solutions has been studied using multi-technique approach. Various micellar parameters such as critical micelle concentration (cmc), degree of counter ion dissociation (α), aggregation number (Nagg) as well as some thermodynamic parameters such as standard free energy of micellization (G°m), standard enthalpy of micellization (H°m) and standard entropy of micellization (S°m) and surface properties from surface tension measurement have been evaluated. A significant decrease in cmc, and increase in degree of counter ion dissociation along with increase in N agg is observed. The aggregation behaviour of SDS is also studied in presence of ILs having different alkyl chain length in their imidazolium cations. A decrease in CMC of SDS observed, and trend of decrease in CMC is reported as [hmim][Cl] N [bmim][PF6] N [emim][PF6]. The micropolarity and microviscosity of micellar media are accessed with fluorescence probe studies. The effect of chain length of IL cation has been also explored on aggregation behaviour. The FTIR technique is employed to evaluate possible interactions between SDS and IL [emim][PF 6 ] molecules, the information regarding size of SDS micelle in presence of IL [emim][PF 6 ] has been explored by DLS technique.
Journal of Colloid and Interface Science, 2011
The impetus for the increasing interest in studying surface active ionic liquids (SAILs; ionic liquids with long-chain ''tails'') is the enormous potential for their applications, e.g., in nanotechnology and biomedicine. The progress in these fields rests on understanding the relationship between surfactant structure and solution properties, hence applications. This need has prompted us to extend our previous study on 1-(1-hexadecyl)-3-methylimidazolium chloride to 1-(1-alkyl)-3-methylimidazolium chlorides, with alkyl chains containing 10, 12, and 14 carbons. In addition to investigating relevant micellar properties, we have compared the solution properties of the imidazolium-based surfactants with: 1-(1-alkyl)pyridinium chlorides, and benzyl (2-acylaminoethyl)dimethylammonium chlorides. The former series carries a heterocyclic ring head-group, but does not possess a hydrogen that is as acidic as H2 of the imidazolium ring. The latter series carries an aromatic ring, a quaternary nitrogen and (a hydrogen-bond forming) amide group. The properties of the imidazolium and pyridinium surfactants were determined in the temperature range from 15 to 75°C. The techniques employed were conductivity, isothermal titration calorimetry, and static light scattering. The results showed the important effects of the interactions in the interfacial region on the micellar properties over the temperature range studied.