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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 4: Colloidal Fluids
CPP 4.6: Talk
Monday, February 25, 2008, 16:00–16:15, C 264
Relating structure, dynamics and rheology of soft micellar glasses — •Jörg Stellbrink, Barbara Lonetti, Marco Laurati, Lutz Willner, and Dieter Richter — IFF, Forschungszentrum Jülich, D-52425 Jülich
Soft colloids are the link between colloids and polymers, showing some interesting features, which originate from their special hybrid character. Recently, regular star polymers and block copolymer micelles have been independently used to investigate structure, dynamics and rheology on approaching the glass phase as a function of softness.
For kinetically frozen (PEPm-PEOn) block copolymer micelles we have shown, that the architecture of the individual micelle can be adjusted between the limits compact sphere like (m≈n) and star-like (m≫n). At the same time the (repulsive) micellar interactions vary from hard sphere like to ultra soft. Micellar structure factors in equilibrium can be described starting from either the hard sphere or the ultra-soft pair potential without adjustable parameters. Therefore PEP-PEO micelles are an excellent model system for soft colloids. Special emphasis will be on non-equilibrium phenomena as i.) jamming transitions in concentrated micellar solutions as observed by dynamic light scattering, pfg-nmr and rheology and ii.) the structural response of ordered/disordered colloidal phases to applied external shear as resolved by in situ neutron scattering techniques (Rheo-SANS).
[1] M. Laurati et al., Phys. Rev. Letters, 94, 195504, 2005.
[2] M. Laurati et al., Phys. Rev. E, 76, 041503, 2007.