title: Dynamic phase diagram of soft nanocolloids.
abstract: We present a comprehensive experimental and theoretical study covering micro-, meso- and macroscopic length and time scales, which enables us to establish a generalized view in terms of structure-property relationship and equilibrium dynamics of soft colloids. We introduce a new, tunable block copolymer model system, which allows us to vary the aggregation number, and consequently its softness, by changing the solvophobic-to-solvophilic block ratio (m : n) over two orders of magnitude. Based on a simple and general coarse-grained model of the colloidal interaction potential, we verify the significance of interaction length σint governing both structural and dynamic properties. We put forward a quantitative comparison between theory and experiment without adjustable parameters, covering a broad range of experimental polymer volume fractions (0.001 ≤ϕ≤ 0.5) and regimes from ultra-soft star-like to hard sphere-like particles, that finally results in the dynamic phase diagram of soft colloids. In particular, we find throughout the concentration domain a strong correlation between mesoscopic diffusion and macroscopic viscosity, irrespective of softness, manifested in data collapse on master curves using the interaction length σint as the only relevant parameter. A clear reentrance in the glass transition at high aggregation numbers is found, recovering the predicted hard-sphere (HS) value in the hard-sphere like limit. Finally, the excellent agreement between our new experimental systems with different but already established model systems shows the relevance of block copolymer micelles as a versatile realization of soft colloids and the general validity of a coarse-grained approach for the description of the structure and dynamics of soft colloids.
authors.affiliation: JCNS-1 and ICS-1, Forschungszentrum Jülich, Leo-Brandt-Straße, 52425 Jülich, Germany. s.gupta@fz-juelich.de j.stellbrink@fz-juelich.de.
authors.forename: Sudipta
authors.initials: S
authors.lastname: Gupta
authors.forename: Manuel
authors.initials: M
authors.lastname: Camargo
authors.forename: Jörg
authors.initials: J
authors.lastname: Stellbrink
authors.forename: Jürgen
authors.initials: J
authors.lastname: Allgaier
authors.forename: Aurel
authors.initials: A
authors.lastname: Radulescu
authors.forename: Peter
authors.initials: P
authors.lastname: Lindner
authors.forename: Emanuela
authors.initials: E
authors.lastname: Zaccarelli
authors.forename: Christos N
authors.initials: CN
authors.lastname: Likos
authors.forename: Dieter
authors.initials: D
authors.lastname: Richter