title: Micellar interactions in water-AOT based droplet microemulsions containing hydrophilic and amphiphilic polymers.
abstract: We investigate the influence of addition of hydrophilic and amphiphilic polymer on percolation behavior and micellar interactions in AOT-based water-in-oil droplet microemulsions. We focus on two series of samples having constant molar water to surfactant ratio W = 20 and constant droplet volume fraction Φ = 30%, respectively. From dielectric spectroscopy experiments, we extract the bending rigidity of the surfactant shell by percolation temperature measurements. Depending on droplet size, we find stabilization and destabilization of the surfactant shell upon addition of hydrophilic poly(ethylene glycol) (PEG) (Mn = 3100 g mol(-1)) and amphiphilic poly(styrene)-b-poly(ethylene glycol) copolymer with comparable length of the hydrophilic block. Complementary small angle X-ray scattering experiments corroborate the finding of stabilization for smaller droplets and destabilization of larger droplets. Subsequent analysis of dielectric spectra enables us to extract detailed information about micellar interactions and clustering by evaluating the dielectric high frequency shell relaxation. We interpret the observed results as a possible modification of the inter-droplet charge transfer efficiency by addition of PEG polymer, while the amphiphilic polymer shows a comparable, but dampened effect.
authors: Institute for Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstr. 8, 64289 Darmstadt, Germany.
authors: Markus
authors: M
authors: Appel
authors: Tinka Luise
authors: TL
authors: Spehr
authors: Robert
authors: R
authors: Wipf
authors: Christian
authors: C
authors: Moers
authors: Holger
authors: H
authors: Frey
authors: Bernd
authors: B
authors: Stühn