title: Effect of polymer on the elasticity of surfactant membranes: a light scattering study.
abstract: We have performed a dynamic light-scattering (DLS) investigation of the effect of a water-soluble polymer, polyethylene glycol (PEG), on the bending elastic modulus κ of surfactant membranes. The polymer, in concentrations ranging from 0 to 8 g/L (0 to 0.4 mM), was incorporated into the solvent of sponge phases of the sodium dodecyl sulfate (SDS)-hexanol-brine system. PEG adsorbs into the SDS membranes. The correlation functions of the polymer-doped sponge phases displayed a stretched-exponential decay, appropriately described by the Zilman-Granek (Z-G) theory for fluctuating membranes. The dynamics of the surfactant bilayers was slowed down by the addition of the polymer: Increasing PEG concentrations increase the DLS relaxation times. From the Z-G model we extracted the membrane-bending elastic modulus, as a function of polymer concentration, C(PEG) = κ increases with C(PEG), a behavior opposite to that expected from available models for the interaction between fluid membranes and adsorbing polymers. Our results suggest that the polymer penetrates to some extent the surfactant bilayers.
authors.affiliation: Departamento de Física, Universidad de Sonora, 83000 Hermosillo, Sonora, Mexico.
authors.forename: Ramón
authors.initials: R
authors.lastname: Iñiguez-Palomares
authors.forename: Heriberto
authors.initials: H
authors.lastname: Acuña-Campa
authors.forename: Amir
authors.initials: A
authors.lastname: Maldonado
mesh_terms: D000327:Adsorption; D000438:Alcohols / Q000737:chemistry; D000465:Algorithms; D004548:Elasticity; D008027:Light; D010825:Physics / Q000379:methods*; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D012542:Scattering, Radiation; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry; D014783:Viscosity
chemical_list: D000438:Alcohols; D011108:Polymers; D012997:Solvents; D013501:Surface-Active Agents; D012967:Sodium Dodecyl Sulfate; D011092:Polyethylene Glycols