title: Aggregation properties of diacyl lysine surfactant compounds: hydrophobic chain length and counterion effect.
abstract: In this paper, we report on the study of aqueous solution and aggregation properties of diacyl Lysine surfactant salts with several surfactant counterions at a fixed hydrophobic chain length. They present a critical micellar concentration nearly independent of the counterion. The area per surfactant molecule is around 1.3 nm (2) also independent of the counterion. We have also studied the dry state crystallization of these surfactant salts. We show that small counterion systems tend to form bicontinuous cubic structures and that the increase in counterion size tends to form lamellar structures. We have compared this behavior with the dry state crystallization of the diacyl Lysine surfactants as a function of hydrophobic chain length. For long hydrophobic chains, the crystal structure is lamellar, while for intermediate, length is cubic. Among the structures studied, the one with the shortest chain length crystallizes in a hexagonal inverse phase.
authors.affiliation: Institut d'Investigacions Quimiques i Ambientals de Barcelona, IIQAB, CSIC, c/ Jordi Girona 18-26, 08034 Barcelona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Pinazo
authors.forename: L
authors.initials: L
authors.lastname: Pérez
authors.forename: M
authors.initials: M
authors.lastname: Lozano
authors.forename: M
authors.initials: M
authors.lastname: Angelet
authors.forename: M R
authors.initials: MR
authors.lastname: Infante
authors.forename: M P
authors.initials: MP
authors.lastname: Vinardell
authors.forename: R
authors.initials: R
authors.lastname: Pons
mesh_terms: D000215:Acylation; D000465:Algorithms; D003460:Crystallization; D057927:Hydrophobic and Hydrophilic Interactions; D008239:Lysine / Q000031:analogs & derivatives*; D015394:Molecular Structure; D012996:Solutions / Q000737:chemistry; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D012996:Solutions; D013501:Surface-Active Agents; D014867:Water; D008239:Lysine