Micellization Behavior of Conventional Cationic Surfactants within Glycerol-Based Deep Eutectic Solvent

Abstract

The aggregation behavior of two cationic surfactants, i.e., cetyldimethylethanolammonium bromide (CDMEAB) and cetyltributylphosphonium bromide (CTBPB), within an aqueous deep eutectic solvent (DES) is studied. The synthesized DES is composed of 1:2 mole ratio of choline chloride and glycerol and is further characterized by Fourier transform infrared (FTIR) and 1 H NMR spectroscopy techniques. The critical micellar concentration (CMC), micellar size, and intermolecular interaction in surfactants within Gly-based DES solutions are investigated by various techniques including surface tension, conductivity, fluorescence, dynamic light scattering (DLS), FTIR, 1 H NMR, and two-dimensional (2D) nuclear Overhauser effect spectroscopy (NOESY). The various interfacial properties and thermodynamic parameters are determined in the presence of 5 wt % glyceline (Gly)-based DES in an aqueous solution. The CMC, aggregation number ( N agg ), and Stern–Volmer constant ( K sv ) have also been determined by a steady-state fluorescence method. DLS is used to obtain information regarding the size of the aggregates formed by the cationic surfactants in DES solutions. FTIR spectroscopy is used to study the surfactant–DES interactions that tune the micellar structure of the surfactants within the Gly-based DES solution. The functional groups involved in the interactions (H-bonding and electrostatic) are the head groups (HO–CH 2 –CH 2 –N + ion for CDMEAB and quaternary phosphonium (P + ) ion for CTBPB) of the surfactants with the −OH-containing Gly DES. The hydrophobic moieties are involved in the hydrophobic interactions. The 1 H NMR data show that differences in chemical shifts can provide significant information about the interactions taking place within the system. 1 H NMR and NOESY techniques are further employed to strengthen our claim on the feasible structural arrangements within the aqueous surfactant–DES self-assembled structures. It is observed that both the cationic surfactants, i.e., CDMEAB and CTBPB, form self-assembled nanostructures in the Gly-based DES solutions. The present results are expected to be useful for colloidal solutions of DES and their mixtures with water.

Investigation of the Mechanism and Effect of Citric Acid-Based Deep Eutectic Solvents Inhibiting Hydration and Expansion of Gas Shale Clay Minerals

“…The first peak observed at 3444 cm –1 corresponds to the stretching vibration peaks of O–H and N–H in ammonium salt. The wavelength of 3132–3572 cm –1 corresponds to the hydrogen bond band . Cit-DES and DES + CTAB exhibit wide hydrogen bond bands, showing that both have complex hydrogen bond networks.…”

“…The specific experimental steps are as follows: (1) The sample was soaked in distilled water for 48 h, then dried at 65 °C for 24 h. The contact angle of shale and water was measured after soaking in distilled water. 29 Cit-DES and DES + CTAB exhibit wide hydrogen bond bands, showing that both have complex hydrogen bond networks. The 1455.55 cm −1 represents the stretching vibration peak in the C−H plane, while 1164.09 cm −1 corresponds to the stretching vibration peak of C−N.…”

A simple HPLC-DAD method for analysis of phenolic acids: Addition effect of a hydrophilic deep eutectic solvent to the mobile phase

“…Other interesting bands between 1,100 and 1,500 cm À1 in the fingerprint region of all spectra of DESs, that be assigned to C-O and C-C-O stretching's and C-O-H bending vibrations were observed [37,38].…”

Time‐Dependent Hydrogen Bond Network Formation in Glycerol‐Based Deep Eutectic Solvents

“…[43] Similarly to ILs, [44] addition of water to glyceline can significantly reduce its density [45,46] and viscosity, [47] but also increase the electrical conductivity, [48] transport properties [49] or heat capacity, [50] due to the decreased molecular packing intensity resulting from more water-HBA/ HBD and less HBA-HBD interactions. [51] Consequently, addition of small water fractions to glyceline can facilitate its applications, e. g. biodiesel production, [52] induce the micellization of surfactants in DES [53] or improve the yield of a reaction in a medium. [17,54] In this study, two different types of hydrogen bond donors are selected to simultaneously oversaturate HBA in glyceline (ChCl:Gly 1 : 2) and subsequently formed glycholine (1 : 4), in order to understand the HBD influence on the structural arrangement of Gly-based DESs.…”

“…Similarly to ILs, [44] addition of water to glyceline can significantly reduce its density [45,46] and viscosity, [47] but also increase the electrical conductivity, [48] transport properties [49] or heat capacity, [50] due to the decreased molecular packing intensity resulting from more water‐HBA/HBD and less HBA‐HBD interactions [51] . Consequently, addition of small water fractions to glyceline can facilitate its applications, e. g. biodiesel production, [52] induce the micellization of surfactants in DES [53] or improve the yield of a reaction in a medium [17,54] …”