Highly nonlinear dynamics in a slowly sedimenting colloidal gel

Luca Cipelletti (1) , Giovanni Brambilla (1) , Stefano Buzzaccaro (2) , Roberto Piazza , Ludovic Berthier (1)

1 L2C - Laboratoire Charles Coulomb
2 Dipartimento di Chimica

We use a combination of original light scattering techniques and particles with unique optical properties to investigate the behavior of suspensions of attractive colloids under gravitational stress, following over time the concentration profile, the velocity profile, and the microscopic dynamics [1,2]. During the compression regime, the sedimentation velocity grows nearly linearly with height, implying that the gel settling may be fully described by a (time-dependent) strain rate. We find that the microscopic dynamics exhibit remarkable scaling properties when time is normalized by strain rate, showing that the gel microscopic restructuring is dominated by its macroscopic deformation. [1] G. Brambilla et al., Phys. Rev. Lett. 106, 118302 (2011). [2] "Gels settle down", in Physics, Spotlighting exceptional research: http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.106.118302

Domaines: Matière Molle [cond-mat.soft]

Luca Cipelletti, Giovanni Brambilla, Stefano Buzzaccaro, Roberto Piazza, Ludovic Berthier. Highly nonlinear dynamics in a slowly sedimenting colloidal gel. 8th Liquid Matter Conference, Sep 2011, Vienne, Austria. ⟨hal-00610242⟩