title: The effect of electrolyte on the morphology of vesicles composed of the dialkyl polyoxyethylene ether surfactant 2C18E12.
abstract: Small-angle neutron-scattering (SANS) studies were performed on vesicles composed of 1,2-di-O-octadecyl-rac-glyceryl-3-(omega-methoxydodecaethylene glycol), in deuterium oxide (D2O) solutions with various ionic strengths of LiCl, NaCl and NaI. Gross vesicle morphologies, examined using freeze-fracture electron microscopy, showed that NaCl promoted the formation of multilamellar vesicles. Model fitting of the SANS data showed changes in bilayer parameters such as thickness and repeat spacings, in response to the presence of ions in the bulk solution. 2C18E12 vesicles in D2O are shown to exist as predominantly unilamellar structures with a bilayer thickness of approximately 51 A. Vesicles in increasing concentrations of LiCl and NaCl exhibit decreased layer thickness and increased lamelarity. Little change was observed for vesicles formed in NaI solutions. We suggest that these changes result from intrusion of E12 headgroups into the alkyl chain region of the vesicle bilayers, in response to the increase in concentration of ions present and their charge density.
authors.affiliation: Department of Pharmacy, King's College London, Franklin Wilkins Building, 150 Stamford Street, London SE1 9NN, UK.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Harvey
authors.forename: Richard K
authors.initials: RK
authors.lastname: Heenan
authors.forename: David J
authors.initials: DJ
authors.lastname: Barlow
authors.forename: M Jayne
authors.initials: MJ
authors.lastname: Lawrence
mesh_terms: D017666:Deuterium Oxide; D004573:Electrolytes / Q000737:chemistry / Q000494:pharmacology*; D005614:Freeze Fracturing; D008051:Lipid Bilayers / Q000737:chemistry*; D018021:Lithium Chloride / Q000737:chemistry; D008854:Microscopy, Electron; D033363:Neutron Diffraction; D011092:Polyethylene Glycols / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry; D055672:Static Electricity; D013501:Surface-Active Agents / Q000737:chemistry*; D014280:Triglycerides / Q000737:chemistry*
chemical_list: C504326:1,2-di-O-octadecylglyceryl-3-(omega-methoxydodecaethylene glycol); D004573:Electrolytes; D008051:Lipid Bilayers; D013501:Surface-Active Agents; D014280:Triglycerides; D011092:Polyethylene Glycols; D012965:Sodium Chloride; D018021:Lithium Chloride; D017666:Deuterium Oxide