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The present investigation involves the synthesis of a series of novel green ethylene oxide-linked diester-functionalized cationic gemini surfactants 2,2′-[(oxybis(ethane-1,2-diyl))bis(oxy)]bis(N-alkyl-N,N-dimethyl-2-oxoethanaminium) dichloride (Cm-DEG-Cm; m = 12, 14, 16). These compounds were characterized by 1H-NMR, MS-ESI (+), FT-IR spectroscopy and elemental analysis; their solution properties were evaluated by surface tension and rheology measurements. The dimeric surfactant, Cm-DEG-Cm, possesses improved physicochemical properties as compared to its monomeric counterpart. Much lower critical micelle concentration (cmc) makes the cationic gemini surfactants more useful for the biomedical, pharmaceutical, industrial and academic sectors. Longer the alkyl chain of surfactants lower are the cmc values, the order is C16-DEG-C16 < C14-DEG-C14 < C12-DEG-C12. For all the three synthesized gemini surfactants no cloud point was noticed in between the temperatures 0 °C to 100 °C at the concentrations 0.002 mM, 0.02 mM and 0.2 mM of the aqueous surfactant solutions which is a beneficial factor for the use of these amphiphiles in various areas of application. [ABSTRACT FROM AUTHOR]

The present study deals with the solubility enhancement of the two polycyclic aromatic hydrocarbons (PAHs) anthracene and pyrene in the aqueous micellar system of the cationic ester-containing cleavable gemini surfactant ethane-1,2-diyl-bis(N,N-dimethyl-N-tetradecylammoniumacetoxy) dichloride (14-E2-14 = C14H29(CH3)2N+(CH2COOCH2)2N+(CH3)2C14H29 · 2Cl-)), and its equimolar binary mixtures with some typical conventional cationic, anionic and non-ionic surfactants. The surface tension and conductivity measurements were used to evaluate the physicochemical parameters such as the critical micelle concentration (CMC), the interaction parameter (ßm) and Gibbs excess free energy of micellization (ΔGexm) of the systems. The extent of solubilization of the micellar systems towards PAHs has been quantified in terms of molar solublization ratio (MSR), micellar/water partition coefficient (ln Km) and the standard Gibbs free energy of solubilization (ΔGs0). Above the CMC, all studied single as well as binary gemini-conventional surfactant systems show an increase in solubilization of the PAHs. For pure systems, the MSR value of Brij 58 was found to be significantly higher than that of the other amphiphiles. Amongst the mixed surfactant systems, the solubility enhancement of anthracene is found to be maximum in the 14-E2-14 + SDS/SDBS system whereas the system14-E2-14 + Brij 58 shows a higher solubility for pyrene. [ABSTRACT FROM AUTHOR]

This study is an approach to especially investigate (i) the micellization behaviour of a cationic gemini surfactant 16-E2-16 (ethane-1,2-diylbis(N,N-dimethyl-N-hexadecylammoniumacetoxy) dichloride) and its equimolar binary mixtures with conventional cationic (CTAC), anionic (SDS), non-ionic (Brij 58) surfactants, and (ii) the solubilization capacity of the pure/mixed surfactant systems towards polycyclic aromatic hydrocarbons (PAHs) by 1H NMR spectroscopy. Proton chemical shifts (δ , ppm) of the binary or ternary surfactant/solute systems have been compared with the pure surfactant solutions. The results (δ values) indicate favoured micellization for all the surfactant solutions and the extent of solubilization depends on the nature of surfactants as well as solutes. Location of the PAHs in different parts, such as palisade layer, inner palisade layer and core of micelles alter the δ values. More pronounced changes in δ value of various protons of CTAC and Brij 58 indicate higher solubilization of pyrene. Among all the three surfactant combinations, 16-E2-16 + SDS is the most compact system as compared to the 16-E2-16 + CTAC and 16-E2-16 + Brij 58 systems. Image 1 • Study of equimolar gemini-conventional surfactant mixtures by 1H NMR spectroscopy. • Chemical shift (δ) data imply attractive interaction among surfactant components. • Pure Brij 58 and CTAC micelles show maximum dissolution capacity towards pyrene. • PAH−solubility in anionic surfactant micelles is lower than the cationic micelles. • Change in δ values suggest distinct location sites of solutes in micellar solutions. [ABSTRACT FROM AUTHOR]