Université de Fribourg

Brownian dynamics of colloidal microspheres with tunable elastic properties from soft to hard

Yoon, Jiwon ; Cardinaux, Frédéric ; Lapointe, Clayton ; Zhang, Chi ; Mason, Thomas G. ; Ahn, Kyung Hyun ; Scheffold, Frank

In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2018, vol. 546, p. 360–365

We study the Brownian thermal motion of a colloidal model system made by emulsifying hot liquid α-eicosene wax into an aqueous surfactant solution of sodium dodecyl sulfate (SDS). When this waxy oil-in-water emulsion is cooled below α- eicosene's melting point of Tc ≃ 25 °C, the microscale emulsion droplets solidify, effectively yielding a dispersed particulate system. So, the...

Université de Fribourg

Structure of marginally jammed polydisperse packings of frictionless spheres

Zhang, Chi ; O'Donovan, Cathal B. ; Corwin, Eric I. ; Cardinaux, Frédéric ; Mason, Thomas G. ; Möbius, Matthias E. ; Scheffold, Frank

In: Physical Review E, 2015, vol. 91, no. 3, p. 032302

We model the packing structure of a marginally jammed bulk ensemble of polydisperse spheres. To this end we expand on the granocentric model [Clusel et al., Nature (London) 460, 611 (2009)], explicitly taking into account rattlers. This leads to a relationship between the characteristic parameters of the packing, such as the mean number of neighbors and the fraction of rattlers, and the radial...

Université de Fribourg

Accounting for inertia effects to access the high-frequency microrheology of viscoelastic fluids

Domínguez-García, P. ; Cardinaux, Frédéric ; Bertseva, Elena ; Forró, László ; Scheffold, Frank ; Jeney, Sylvia

In: Physical Review E, 2014, vol. 90, no. 6, p. 060301

We study the Brownian motion of microbeads immersed in water and in a viscoelastic wormlike micelles solution by optical trapping interferometry and diffusing wave spectroscopy. Through the mean-square displacement obtained from both techniques, we deduce the mechanical properties of the fluids at high frequencies by explicitly accounting for inertia effects of the particle and the surrounding...

Université de Fribourg

The jamming elasticity of emulsions stabilized by ionic surfactants

Scheffold, Frank ; Wilking, James N. ; Haberko, Jakub ; Cardinaux, Frédéric ; Mason, Thomas G.

In: Soft Matter, 2014, vol. 10, no. 28, p. 5040–5044

Oil-in-water emulsions composed of colloidal-scale droplets are often stabilized using ionic surfactants that provide a repulsive interaction between neighboring droplet interfaces, thereby inhibiting coalescence. If the droplet volume fraction is raised rapidly by applying an osmotic pressure, the droplets remain disordered, undergo an ergodic–nonergodic transition, and jam. If the applied...

Université de Fribourg

Linear and nonlinear rheology of dense emulsions across the glass and the jamming regimes

Scheffold, Frank ; Cardinaux, Frédéric ; Mason, Thomas G.

In: Journal of Physics: Condensed Matter, 2013, vol. 25, no. 50, p. 502101

We discuss the linear and nonlinear rheology of concentrated microscale emulsions, amorphous disordered solids composed of repulsive and deformable soft colloidal spheres. Based on recent results from simulation and theory, we derive quantitative predictions for the dependences of the elastic shear modulus and the yield stress on the droplet volume fraction. The remarkable agreement with...

Université de Fribourg

Elasticity and glassy dynamics of dense emulsions

Cardinaux, Frédéric ; Mason, Thomas G. ; Scheffold, Frank

In: AIP Conference Proceedings, 2013, vol. 1518, p. 222–226

We present a rheology and light scattering study of the dynamical properties of dense emulsions at volume fractions ranging from viscous liquid to deeply jammed states. From temporally and spatially revolved dynamic light scattering we obtain detailed information about the internal dynamics. Our measurements thus allow a direct study of heterogeneous nature of the relaxation processes involved in...

Université de Fribourg

Quasi-real-time analysis of dynamic near field scattering data using a graphics processing unit

Cerchiari, Giovanni ; Croccolo, Fabrizio ; Cardinaux, Frédéric ; Scheffold, Frank

In: Review of Scientific Instruments, 2012, vol. 83, no. 10, p. 106101

We present an implementation of the analysis of dynamic near field scattering (NFS) data using a graphics processing unit. We introduce an optimized data management scheme thereby limiting the number of operations required. Overall, we reduce the processing time from hours to minutes, for typical experimental conditions. Previously the limiting step in such experiments, the processing time is now...

Université de Fribourg

Magnetic orientation of soft particles in a jammed solid

Dagallier, Camille ; Cardinaux, Frédéric ; Dietsch, Hervé ; Scheffold, Frank

In: Soft Matter, 2012, vol. 8, no. 15, p. 4067-4071

Densely packed atoms, molecules, or small particles can get trapped in a jammed state thereby avoiding crystallization. The resulting amorphous structures display complex, spatially heterogeneous, trapping potentials in stark contrast to the uniform case of a crystal. Here we study active and passive rotational motion in a jammed colloidal dispersion of particles consisting of an...

Université de Fribourg

Cluster-Driven dynamical arrest in concentrated lysozyme solutions

Cardinaux, Frédéric ; Zaccarelli, Emanuela ; Stradner, Anna ; Bucciarelli, Saskia ; Farago, Bela ; Egelhaaf, Stefan U. ; Sciortino, Francesco ; Schurtenberger, Peter

In: The Journal of Physical Chemistry B, 2011, vol. 115, no. 22, p. 7227–7237

We present a detailed experimental and numerical study of the structural and dynamical properties of salt-free lysozyme solutions. In particular, by combining small-angle X-ray scattering (SAXS) data with neutron spin echo (NSE) and rheology experiments, we are able to identify that an arrest transition takes place at intermediate densities, driven by the slowing down of the cluster motion. Using...

Université de Fribourg

Phase separation and dynamical arrest for particles interacting with mixed potentials—the case of globular proteins revisited

Gibaud, Thomas ; Cardinaux, Frédéric ; Bergenholtz, Johan ; Stradner, Anna ; Schurtenberger, Peter

In: Soft Matter, 2011, vol. 7, no. 3, p. 857

We examine the applicability of the extended law of corresponding states (ELCS) to equilibrium and non equilibrium features of the state diagram of the globular protein lysozyme. We provide compelling evidence that the ELCS correctly reproduces the location of the binodal for different ionic strengths, but fails in describing the location of the arrest line. We subsequently use Mode Coupling...