title: Aggregation behavior of SDS/CTAB catanionic surfactant mixture in aqueous solution and at the air/water interface.
abstract: Herein, we report the aggregation behavior of catanionic mixtures of the anionic surfactant sodium dodecyl sulfate (SDS) and the cationic surfactant cetyltrimethylammonium bromide (CTAB) in solution and at the air/water interface obtained by the Langmuir-Blodgett (LB) technique. We employed Fourier transform infrared spectroscopy, in situ phase-contrast inverted microscopy, scanning electron microscopy, and atomic force microscopy to characterize the systems in solution, at the air/water interface, and in LB films. We found spherical vesicles at the SDS/CTAB ratio of 35/65 in aqueous solution and an ordered aggregated morphology called surface micelles at SDS/CTAB ratios of 35/65 to 65/35 at the air/water interface. Other mixtures (SDS/CTAB = 90/10, 10/90) were found to contain mostly disordered aggregated microstructures. An in situ time-dependent study of surface micelle formation at the air/water interface showed micelle ripening through the fusion of smaller micelles. These micelles were successfully immobilized on a glass substrate by the LB technique. Overall, the study might find application in the fundamental science of the physical chemistry of surfactant systems, as well as in the preparation of drug delivery system.
authors.affiliation: Department of Spectroscopy, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, India.
authors.forename: Bidisha
authors.initials: B
authors.lastname: Tah
authors.forename: Prabir
authors.initials: P
authors.lastname: Pal
authors.forename: Mrityunjoy
authors.initials: M
authors.lastname: Mahato
authors.forename: G B
authors.initials: GB
authors.lastname: Talapatra
mesh_terms: D000838:Anions / Q000737:chemistry*; D002412:Cations / Q000737:chemistry*; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry; D008055:Lipids / Q000737:chemistry; D018625:Microscopy, Atomic Force; D008854:Microscopy, Electron / Q000379:methods; D015394:Molecular Structure; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D055672:Static Electricity; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D000838:Anions; D002412:Cations; D002593:Cetrimonium Compounds; D008051:Lipid Bilayers; D008055:Lipids; D013501:Surface-Active Agents; D014867:Water; D012967:Sodium Dodecyl Sulfate; D000077286:Cetrimonium