title: Dynamics of microemulsions bridged with hydrophobically end-capped star polymers studied by neutron spin-echo.
abstract: The mesoscopic dynamical properties of oil-in-water microemulsions (MEs) bridged with telechelic polymers of different number of arms and with different lengths of hydrophobic stickers were studied with neutron spin-echo (NSE) probing the dynamics in the size range of individual ME droplets. These results then were compared to those of dynamicic light scattering (DLS) which allow to investigate the dynamics on a much larger length scale. Studies were performed as a function of the polymer concentration, number of polymer arms, and length of the hydrophobic end-group. In general it is observed that the polymer bridging has a rather small influence on the local dynamics, despite the fact that the polymer addition leads to an increase of viscosity by several orders of magnitude. In contrast to results from rheology and DLS, where the dynamics on much larger length and time scales are observed, NSE shows that the linear polymer is more efficient in arresting the motion of individual ME droplets. This finding can be explained by a simple simulation, merely by the fact that the interconnection of droplets becomes more efficient with a decreasing number of arms. This means that the dynamics observed on the short and on the longer length scale depend in an opposite way on the number of arms and hydrophobic stickers.
authors: Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, Sekr. TC 7, D-10623 Berlin, Germany.
authors: I
authors: I
authors: Hoffmann
authors: Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, Sekr. TC 7, D-10623 Berlin, Germany.
authors: Paula Malo
authors: PM
authors: de Molina
authors: Institut Max von Laue-Paul Langevin (ILL), F-38042 Grenoble Cedex 9, France.
authors: B
authors: B
authors: Farago
authors: Institut Max von Laue-Paul Langevin (ILL), F-38042 Grenoble Cedex 9, France.
authors: P
authors: P
authors: Falus
authors: Fraunhofer Institut für Angewandte Polymerforschung IAP, Geiselbergstraße 69, 14476 Potsdam-Golm, Germany.
authors: Christoph
authors: C
authors: Herfurth
authors: Fraunhofer Institut für Angewandte Polymerforschung IAP, Geiselbergstraße 69, 14476 Potsdam-Golm, Germany.
authors: André
authors: A
authors: Laschewsky
authors: Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, Sekr. TC 7, D-10623 Berlin, Germany.
authors: M
authors: M
authors: Gradzielski