Regensburg 2010 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 1: Topical Session Glass Dynamics I
MM 1.2: Topical Talk
Montag, 22. März 2010, 10:45–11:15, H16
Relaxation and flow in glassy colloids — •Hans M. Wyss1,2, Johan Mattsson1,3, Alberto Fernandez-Nieves1,4, Kunimasa Miyazaki5,6, Zhibing Hu7, David R. Reichman5, and David A. Weitz1 — 1Harvard University, Cambridge, USA — 2TU Eindhoven, Eindhoven, Netherlands — 3Chalmers University, Gothenburg, Sweden — 4Georgia Tech, Atlanta, USA — 5Columbia University, New York, USA — 6Tsukuba University, Tsukuba, Japan — 7University of North Texas, Denton, USA
For different molecular glass-forming liquids, the dynamics of glass formation show broad variations, as often characterized by the concept of fragility - the sensitivity of the viscosity or structural relaxation time on temperature as the glass is approached. Glass formation can also be studied in colloidal materials, where increasing concentration has an effect analogous to decreasing the temperature in molecular liquids. However, in this analogy only highly fragile behavior has been observed.
In this talk I will show that by using soft, deformable particles the concept of fragility can be extended to colloidal glasses. We capture the entire range of dynamic behaviors merely by varying the softness of the individual mesoscopic particles. Hard particles make "fragile" glasses and soft particles make non-fragile, or "strong", glasses. Remarkably, we find that elasticity has an equivalent effect in molecular systems, where elasticity directly reflects fragility. I will further show how in colloids an externally enforced flow can be used to further study the structural relaxation in these materials.