Investigating the Influence of Aromatic Counterions on the Micellar Structure and Aggregation Behavior of Morpholinium-Based Surface-Active Ionic Liquids in an Aqueous Solution.

Two morpholinium-based surface-active ionic liquids (SAILs) with aromatic counterions were synthesized, namely, -dodecyl--methylmorpholinium salicylate [Cmmor][Sal] and -dodecyl--methylmorpholinium 3-hydroxy-2-naphthoate [Cmmor][3--2-], and explored their aggregation behavior in aqueous solutions systematically. Electrical conductivity, small-angle neutron scattering (SANS), surface tension (ST), and UV-vis spectroscopy measurements were employed to determine various thermodynamic, micellar, and interfacial parameters, like the degree of counterion binding (β), critical micelle concentration (CMC), minimum area per molecule (), surface excess concentration (Γ), standard Gibbs free energy of adsorption (Δ), aggregation number (), standard Gibbs free energy of micellization (Δ), standard enthalpy of micelle formation (Δ), and the standard entropy of micellization (Δ) in an aqueous solution. Incorporating the aromatic counterions favors significantly excellent micellization properties over conventional halogenated SAILs such as [Cmmor][Br].

Synthesis, Self-Aggregation, Surface Characteristics, Electrochemical Property, Micelle Size, and Antimicrobial Activity of a Halogen-Free Picoline-Based Surface-Active Ionic Liquid.

We present a new approach toward the design of a halogen-free picoline-based surface-active ionic liquid (SAIL) (1-octyl-4-methyl pyridinium dodecyl sulfate) [CγPic]DS consisting of long dodecyl sulfate (DS) as an anion. The surface properties, micellization behavior, and antimicrobial activity in an aqueous solution were investigated using tensiometry, conductometry, and ultraviolet (UV) spectroscopy. Incorporating the DS group in SAIL leads to lower critical micellar concentration (CMC) and enhanced adsorption at the air/water interface of the functionalized ionic liquid compared to the C-alkyl chain-substituted pyridine ionic liquids.