title: Interfacial tension in aqueous biopolymer-surfactant mixtures.
abstract: The current study offers a first insight into the interfacial properties of pullulan-sodium dodecyl sulphate (SDS) aqueous two-phase systems (ATPS) in the presence of sodium chloride (NaCl). The effect of composition on the interfacial tension (sigma) in these ATPS was investigated over a wide range of pullulan, SDS and NaCl concentrations. An increase in the interfacial tension was observed with increasing pullulan and SDS concentrations and a small increase was also observed as the NaCl concentration was increased. In both cases the interfacial tension increases were closely related to the phase behaviour of these systems; as a consequence of increasing the pullulan, SDS and/or NaCl concentrations, the system moves further away from the critical point. In all systems interfacial tensions (of the order of muN/m) were comparable with those reported for polymer-polymer ATPS. Interfacial tensions sigma can be well correlated with the difference in pullulan and SDS concentrations between the phases (DeltaC pul and DeltaC SDS) and also the tie-line length (TLL); all yield straight lines on a log-log scale.
authors.affiliation: Centre for Formulation Engineering, Department of Chemical Engineering, University of Birmingham, Birmingham, Edgbaston, B15 2TT, UK. f.spyropoulos@bham.ac.uk
authors.forename: F
authors.initials: F
authors.lastname: Spyropoulos
authors.forename: P
authors.initials: P
authors.lastname: Ding
authors.forename: W J
authors.initials: WJ
authors.lastname: Frith
authors.forename: I T
authors.initials: IT
authors.lastname: Norton
authors.forename: B
authors.initials: B
authors.lastname: Wolf
authors.forename: A W
authors.initials: AW
authors.lastname: Pacek
mesh_terms: D001704:Biopolymers / Q000737:chemistry*; D005936:Glucans / Q000737:chemistry; D012965:Sodium Chloride; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013500:Surface Tension; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water
chemical_list: D001704:Biopolymers; D005936:Glucans; D013501:Surface-Active Agents; D014867:Water; D012967:Sodium Dodecyl Sulfate; D012965:Sodium Chloride; C009109:pullulan