title: Formation of simple single-tailed vesicles mediated by lipophilic solid surfaces.
abstract: Adsorption and aggregation of surfactants at solid-liquid interfaces were fairly well understood, but there was limited knowledge regarding the effect of the presence of a solid surface on aggregate structures in bulk solution. Except for the fatty acid system, most simple single-tailed surfactants (STSs) are well known to form micelles but not vesicles in aqueous solution. Herein, we report a novel phenomenon: with the mediation of lipophilic solid surfaces (LSSs), the zwitterionic STS lauryl sulfobetaine (LSB) formed vesicles from its micellar solution without any additives, producing a mixed solution of vesicles and micelles. More interestingly, the STS vesicles coexisted stably with micelles in the solution and were thermally insensitive even after the removal of LSSs. The quantity of LSB vesicles decreases with the addition of ethanol. The pH effects (4.0-9.0) did not have an obvious influence on the formation and stability of the LSB vesicles. Similar results were obtained from the other STSs, suggesting that the LSS-mediated micelle-to-vesicle transition may be a general phenomenon. We proposed a possible mechanism that adsorption, the matrix effect, and interdigitated bilayer structures were probably crucial for the formation and stability of STS vesicles. We expect this work to provide important insights into the effect of the solid/liquid interface on the self-assembly chemistry of surfactants in bulk solution.
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry (Ministry of Education), Shandong University, Jinan 250100, P. R. China. wghou@sdu.edu.cn.
authors.forename: Na
authors.initials: N
authors.lastname: Du
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry (Ministry of Education), Shandong University, Jinan 250100, P. R. China. wghou@sdu.edu.cn.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry (Ministry of Education), Shandong University, Jinan 250100, P. R. China. wghou@sdu.edu.cn.
authors.forename: Ruiying
authors.initials: R
authors.lastname: Song
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry (Ministry of Education), Shandong University, Jinan 250100, P. R. China. wghou@sdu.edu.cn.
authors.forename: Shue
authors.initials: S
authors.lastname: Song
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry (Ministry of Education), Shandong University, Jinan 250100, P. R. China. wghou@sdu.edu.cn.
authors.forename: Wanguo
authors.initials: W
authors.lastname: Hou