| Abstract
| - This paper aims to provide a practical catanionic vesicle-boosting method by means of cosolvent additionin water and to propose a theoretical explanation which can delineate the general trend of cosolvent effectsand elucidate the possible role of cosolvent in the formation of catanionic vesicles. Effects of four homologouscosolvents (methanol, ethanol, 1-propanol, and 1-butanol) on the spontaneous formation of vesicles fromeight 1:1 anionic−cationic mixed surfactant systems, sodium alkyl sulfates−alkyltrimethylammoniumbromides (CnSO4Na−CmN(CH3)3Br; n = 12, 14; m = 8, 10, 12, 14), at a total surfactant concentration of10 mM were systematically studied. The experimental results revealed that varied changes in vesicleformability of different mixed surfactant systems may result from various kinds and amounts of cosolvent.Four types of cosolvent effects, however, can be classified. Among them, cosolvent effects type 2 and type3 would serve the purpose and were exemplified by C12SO4Na−C10N(CH3)3Br, C14SO4Na−C10N(CH3)3Br,and C12SO4Na−C12N(CH3)3Br mixed surfactants. Furthermore, the effectiveness of vesicle boosting increasesin the order 1-butanol > 1-propanol > ethanol > methanol. An explanation of cosolvent effects based onthe medium dielectric constant was then proposed.
|
