Paper Number
SC5 

Session
Suspensions & Colloids

Title
Binary colloidal glasses: Linear viscoelasticity and its link to local structure and dynamics

Presentation Date and Time
October 15, 2018 (Monday) 11:30

Track / Room
Track 1 / Galleria I

Authors (Click on name to view author profile)

  1. Petekidis, George (FORTH, IESL)
  2. Sentjabrskaja, Tatjana (Heinrich-Heine University Düsseldorf)
  3. Jacob, Alan R. (North Carolina State University, Department of Chemical and Biomolecular Engineeirng)
  4. Laurati, Marco (Universidad de Guanajuato)
  5. Egelhaaf, Stefan U. (Heinrich-Heine University Düsseldorf)
  6. Voigtmann, Thomas (Deutsches Zentrum fur Luft und Raumfahrt, Institut fur Materialphysik im Weltraum)

Author and Affiliation Lines (in printed abstract book)
George Petekidis1, Tatjana Sentjabrskaja2, Alan R. Jacob1, Marco Laurati3, Stefan U. Egelhaaf4, and Thomas Voigtmann5
1IESL, FORTH, Heraklion, Greece; 2Heinrich-Heine University Düsseldorf, Düsseldorf, Germany; 3Universidad de Guanajuato, Leon, Mexico; 4Heinrich-Heine University Düsseldorf, Düsseldorf, Germany; 5Institut fur Materialphysik im Weltraum, Deutsches Zentrum fur Luft und Raumfahrt, Koln, Germany

Speaker / Presenter 
Petekidis, George

Text of Abstract
We study the fluidization of glass-forming colloidal suspensions due to the presence of a faster small component. We present measurements of the dynamical shear moduli by oscillatory rheology and of the local dynamics by confocal microscopy imaging, for binary colloidal hard-sphere mixtures with large size asymmetry (1 : 5), spanning the whole range of mixture compositions for states close to the glass transition. We compare with Brownian Dynamics simulations and predictions from mode-coupling theory based on the Percus-Yevick approximation to the hard-sphere static structure. Experiments, simulations and theory find a strong decrease of the intermediate-frequency mechanical moduli due to mixing, combined with a fluidization of the system but an increasingly better localization of large particles. We find that the Generalized-Stokes Einstein relation applied to the mean square displacements leads to a reasonable estimate of the shear moduli and indicates that the small particles are mainly responsible for the visco-elastic response of the system.