Université de Fribourg

Colloidal fibers as structurant for worm-like micellar solutions

Zanchetta, Giuliano ; Mirzaagha, Shadi ; Guida, Vincenzo ; Zonfrilli, Fabio ; Caggioni, Marco ; Grizzuti, Nino ; Pasquino, Rossana ; Trappe, Veronique

In: Colloid and Polymer Science, 2018, vol. 296, no. 8, p. 1379–1385

We investigate the rheological properties of a simplified version of a liquid detergent composed of an aqueous solution of the linear alkylbenzene sulphonate (LAS) surfactant, in which a small amount of fibers made of hydrogenated castor oil (HCO) is dispersed. At the concentration typically used in detergents, LAS is in a worm-like micellar phase exhibiting a Maxwellian behavior. The...

Université de Fribourg

New aspects in the phase behaviour of poly-N-isopropyl acrylamide: systematic temperature dependent shrinking of PNiPAM assemblies well beyond the LCST

Bischofberger, Irmgard ; Trappe, Veronique

In: Scientific Reports, 2015, vol. 5, p. 15520

We investigate the phase behaviour of aqueous dispersions of poly-N-isopropyl acrylamide (PNiPAM) microgels above their lower critical solution temperature (LCST) and find that beyond a well-defined concentration the systems exhibit a peculiar behaviour: the microgels assemble into space-spanning gels that shrink in time while maintaining the shape of the container in which they have been formed....

Université de Fribourg

A closer look at the synthesis and formation mechanism of hematite nanocubes

Malik, Vikash ; Grobety, Bernard ; Trappe, Veronique ; Dietsch, Herve ; Schurtenberger, Peter

In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2014, vol. 445, p. 21–29

We have synthesized hematite cube-shaped nanoparticles using different synthesis paths to examine the effect of the intermediate product akaganeite (β-FeOOH) on the size and shape of the final hematite particles. Akaganeite spindles and hematite nanocubes are prepared using forced hydrolysis of iron chloride (FeCl₃) salt. We use a combination of transmission electron microscopy (TEM), high...

Université de Fribourg

Generic pathways to stability in concentrated protein mixtures

Voets, Ilja K. ; Trappe, Veronique ; Schurtenberger, Peter

In: Physical Chemistry Chemical Physics, 2012, vol. 14, no. 8, p. 2929-2933

We present a series of experimental results that disclose the crucial role of ionic strength and partial volume fractions in the control of the phase behaviour of binary protein mixtures. Our findings can be understood as that the ionic strength determines the relative contribution of the entropy of the protein counter-ions to the overall thermodynamics of the system. Associative phase separation...

Université de Fribourg

Colloidal gels—low-density disordered solid-like states

Trappe, Veronique ; Sandkühler, Peter

In: Current Opinion in Colloid & Interface Science, 2004, vol. 8, p. 494-500

The analogies between colloidal glasses and gels have stimulated an increased effort in recent years to unify the description of the transitions to these disordered solid-like states within a single conceptual framework. Mode coupling theory, which successfully describes the hard sphere colloidal glass transition, has been extended to describe the effect of weak attractions at large volume...