Banjare Ramesh Kumar, Banjare Manoj Kumar, Behera Kamalakanta, Pandey Siddharth, Ghosh Kallol K
MATS School of Sciences, MATS University, Pagariya Complex, Pandari, Raipur, C.G. 492009, India.
School of Studies in Chemistry, Pt. Ravishankar Shukla University, Raipur, C.G. 492010, India.
ACS Omega. 2020 Jul 27;5(31):19350-19362. doi: 10.1021/acsomega.0c00866. eCollection 2020 Aug 11.
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 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, 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 ( ), and Stern-Volmer constant ( ) 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-CH-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 H NMR data show that differences in chemical shifts can provide significant information about the interactions taking place within the system. 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.
研究了两种阳离子表面活性剂，即十六烷基二甲基乙醇溴化铵（CDMEAB）和十六烷基三丁基溴化鏻（CTBPB）在水相深层共熔溶剂（DES）中的聚集行为。合成的DES由氯化胆碱和甘油按1:2的摩尔比组成，并通过傅里叶变换红外光谱（FTIR）和核磁共振氢谱（H NMR）技术进一步表征。通过表面张力、电导率、荧光、动态光散射（DLS）、FTIR、H NMR和二维（2D）核Overhauser效应光谱（NOESY）等多种技术研究了基于甘油（Gly）的DES溶液中表面活性剂的临界胶束浓度（CMC）、胶束尺寸和分子间相互作用。在水溶液中存在5 wt%基于甘油（Gly）的DES的情况下，测定了各种界面性质和热力学参数。还通过稳态荧光法测定了CMC、聚集数（ ）和斯特恩-沃尔默常数（ ）。DLS用于获取有关阳离子表面活性剂在DES溶液中形成的聚集体尺寸的信息。FTIR光谱用于研究表面活性剂与DES之间的相互作用，这些相互作用调节了基于甘油的DES溶液中表面活性剂的胶束结构。参与相互作用（氢键和静电作用）的官能团是表面活性剂的头基（CDMEAB的HO-CH-CH-N离子和CTBPB的季鏻（P）离子）与含-OH的甘油DES。疏水部分参与疏水相互作用。H NMR数据表明，化学位移的差异可以提供有关系统内发生的相互作用的重要信息。进一步采用H NMR和NOESY技术来加强我们对水相表面活性剂-DES自组装结构内可行结构排列的主张。观察到两种阳离子表面活性剂，即CDMEAB和CTBPB，在基于甘油的DES溶液中形成自组装纳米结构。目前的结果预计对DES的胶体溶液及其与水的混合物有用。
