Unique role of hydrophilic ionic liquid in modifying properties of aqueous Triton X-100

Abstract

Modification of important physicochemical properties of aqueous surfactant solutions can be achieved by addition of environmentally benign room temperature ionic liquids (ILs). While low aqueous solubility of "hydrophobic" ILs limits the amount of IL that may be added to achieve desired changes in the physicochemical properties, hydrophilic ILs do not have such restrictions associated to them. Alterations in the key physicochemical properties of aqueous solutions of a common nonionic surfactant Triton X-100 (TX100) on addition of up to 30 wt % hydrophilic IL 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) are reported. The presence of micellar aggregates in as high as 30 wt % [bmim][BF4]-added aqueous TX100 solutions is established by dynamic light scattering and fluorescence probe behavior. Increasing the concentration of [bmim][BF4] results in decrease in average micellar size and aggregation number and increase in critical micelle concentration, indicating an overall unfavorable aggregation process. Increase in the dipolarity and the microfluidity of the probe cybotactic region within the palisade layer of the micellar phase upon [bmim][BF4] addition implies increased water penetration and the possibility of TX100-[bmim][BF4] interactions. While the changes in some of the physicochemical properties indicate the role of [bmim][BF4] to be similar to a cosurfactant, the IL acts like a cosolvent as far as changes in other properties are concerned. Effectiveness of IL [bmim][BF4] in modifying physicochemical properties of aqueous TX100 is demonstrated.

Effect of [C n mim][Br] Based Ionic Liquids on the Aggregation Behavior of Tetradecyltrimethylammonium Bromide in Aqueous Medium

“…of the ILs in solution. Trends in conductance of aqueous cationic TTAB in the presence of ILs are similar to those observed by Zhang et al [48] for the aqueous Triton X-100 surfactant system in the presence of [C 12 mim][BF 4 ]; these trends are different from those observed for aqueous cationic, anionic, nonionic and aqueous zwitterionic surfactants upon addition of IL [21][22][23][24][25][26][27][28][29][36][37][38][39][40]. For a fixed concentration of TTAB, as the concentration of the ILs was increased from 0.2 to 1.0 wt%, the specific conductance increased by a reasonable amount.…”

“…with n = 6 and 8) and anions [Br -] in the solution after dissociation. Pandey's group has reported similar conductivity behavior for cationic, anionic and non-ionic surfactants such as CTAB [51], SDS [25,26] and Tirton X-100 [23,24]. At fixed concentration of SDS, cetyltrimethylammonium bromide (CTAB) and cetyltrimethylammonium chloride (CTAC), Pal (Fig.…”

“…At lower concentrations, ILs behave as electrolytes and decreases the CMC values of aqueous surfactants, whereas at higher concentrations the CMC of the aqueous surfactant increases, which may be due to cosolvent-type behavior of the ILs [22,24,43]. The cations and anions of the ILs have a profound impact on the physicochemical properties of aqueous surfactant solutions [20][21][22][23][24][25][26][27]47]. Looking at such wider roles for ILs, scientist are encouraged to conduct further research on the unexplored features of the systems for better applications in industry.…”

“…To knowledge, the first report on cationic surfactant self-assembly in a non-aqueous medium was published in 1967 [30]. The aggregation behavior of the ionic [19, 20, 25-29, 31, 33-38, 40], non-ionic [19,23,24,32,41] and zwitterionic [21,22] surfactants with a range of ILs having various cations and anions has been studied in detail. The effect of the hydrophobicity of the alkyl groups of the ILs and surfactant anions on the CMCs, size distributions and thermodynamics of micellization has also been investigated [27,34,35].…”

“…The effect of the hydrophobicity of the alkyl groups of the ILs and surfactant anions on the CMCs, size distributions and thermodynamics of micellization has also been investigated [27,34,35]. Physicochemical properties of aqueous cationic, anionic, non-ionic and zwitterionic surfactants such as the CMC, size of the aggregates, aggregation number, dipolarity and microfluidity have been systematically modified by adding ILs [21][22][23][24][25][26] 4 ] on the physicochemical properties of aqueous anionic and cationic surfactants [28,29,[36][37][38][39][40]. ILs composed of different cations and anions have been extensively studied by various research groups in the field of colloid and interface science and some extensive reviews are available [41][42][43][44][45][46][47][48].…”