title: Effect of hydrophilic groups of Ca surfactants and hydrophobic chains of C(n)DMAO on coordinated vesicle formation.
abstract: The effects of hydrophilic headgroups of Ca surfactants, calcium dodecylsulfate (Ca(DS)(2)), calcium dodecylsulfonate (Ca(DSA)(2)), and calcium laurate (CaL(2)) and hydrophobic chains of alkyldimethylamine oxide (C(n)DMAO, n = 12, 14, 16) on the formation of Ca(2+)-ligand coordinated vesicles was investigated in detail. On the basis of phase behavior studies, rheological properties and freeze-fracture transmission electron microscope (FF-TEM) images were measured. Quite different phase behaviors were observed in different surfactant systems. For a Ca surfactant with a highly polar group, Ca(DS)(2), vesicles were observed in all Ca(DS)(2)/C(n)DMAO (n = 12, 14, and 16) systems, whereas for Ca surfactant with lower polar group, Ca(DSA)(2), vesicles can form in Ca(DSA)(2)/C(n)DMAO systems of n = 14 and 16 but not for n = 12. For CaL(2), the surfactant with the least polar group, vesicles form only in the CaL(2)/C(16)DMAO system. The results demonstrate that in the systems formed by Ca surfactants and C(n)DMAO, the formation of vesicles is driven not only by interaction between Ca(2+) and the N → O groups of C(n)DMAO but also by electrostatic and hydrophobic interactions. Vesicles prefer to form in Ca surfactants with highly polar headgroups and C(n)DMAO with long chain length.
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education, Jinan 250100, China.
authors.forename: Hongshan
authors.initials: H
authors.lastname: Tian
authors.forename: Qi
authors.initials: Q
authors.lastname: Ding
authors.forename: Juan
authors.initials: J
authors.lastname: Zhang
authors.forename: Aixin
authors.initials: A
authors.lastname: Song
authors.forename: Jingcheng
authors.initials: J
authors.lastname: Hao
mesh_terms: D002118:Calcium / Q000737:chemistry*; D004123:Dimethylamines / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D008024:Ligands; D008567:Membranes, Artificial; D012212:Rheology; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D004123:Dimethylamines; D008024:Ligands; D008567:Membranes, Artificial; D013501:Surface-Active Agents; D014867:Water; D002118:Calcium