New catanionic surfactants based on 1-alkyl-3-methylimidazolium alkylsulfonates, [CnH2n+1mim][CmH2m+1SO3]: mesomorphism and aggregation

摘要: Anionic and cationic alkyl-chain effects on the self-aggregation of both neat aqueous solutions 1-alkyl-3-methylimidazolium alkylsulfonate salts ([CnH2n+1mim][CmH2m+1SO3]; n = 8, 10 or 12; m 1 4 8; 8) have been investigated. Some these constitute a novel family pure catanionic surfactants in solution. Examples this class materials are rare; they distinct from mixed cationic–anionic (obtained by mixing two salts) gemini (with more amphiphilic groups bound covalent linker). Fluorescence spectroscopy interfacial tension measurements used to determine critical micelle concentrations (CMCs), surface activity, compare alkyl-substitution patterns cation anion surfactant properties salts. With relatively small methylsulfonate anions (n 12, 1), behave as conventional single chain surfactants, showing decrease CMC upon increase alkyl length (n) cation. When character is present 8), with values lower than those corresponding analogues, which exhibited an unanticipated enhanced reduction tension, were obtained. In addition, thermotropic phase behaviour [C8H18mim][C8H18SO3] was investigated using variable temperature X-ray scattering, polarising optical microscopy differential scanning calorimetry; formation smectic liquid crystalline broad range observed.