title: Signature of a type-A glass transition and intrinsic confinement effects in a binary glass-forming system.
abstract: We study dynamically highly asymmetric binary mixtures comprised of small methyl tetrahydrofuran (MTHF) molecules and polystyrene. Combined use of dielectric spectroscopy, 2H nuclear magnetic resonance, incoherent quasielastic neutron scattering, and depolarized dynamic light scattering allows us to selectively probe the dynamics of the components in a broad dynamic range. It turns out that the mixtures exhibit two glass transitions in a wide concentration range although being fully miscible on a macroscopic scale. In between both glass transition temperatures, the dynamics of the small molecules show strong confinement effects, e.g., a crossover from Vogel-Fulcher to Arrhenius behavior of the time constants. Moreover, the dynamical behavior of small molecules close to the slow matrix is consistent with mode coupling theory predictions for a type-A glass transition, which was expected from recent theoretical and simulation studies in comparable systems.
authors.affiliation: Institut für Festkörperphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany. thomas.blochowicz@physik.tu-darmstadt.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Blochowicz
authors.forename: Sebastian
authors.initials: S
authors.lastname: Schramm
authors.forename: Sorin
authors.initials: S
authors.lastname: Lusceac
authors.forename: Michael
authors.initials: M
authors.lastname: Vogel
authors.forename: Bernd
authors.initials: B
authors.lastname: Stühn
authors.forename: Philipp
authors.initials: P
authors.lastname: Gutfreund
authors.forename: Bernhard
authors.initials: B
authors.lastname: Frick