Université de Fribourg

Hybrid magnetic iron oxide nanoparticles with tunable field-directed self-assembly

Malik, Vikash ; Pal, Antara ; Pravaz, Olivier ; Crassous, Jérôme J. ; Granville, Simon ; Grobety, Bernard ; Hirt, Ann M. ; Dietsch, Hervé ; Schurtenberger, Peter

In: Nanoscale, 2017, vol. 9, p. 14405-14413

We describe the synthesis of hybrid magnetic ellipsoidal nanoparticles that consist of a mixture of two different iron oxide phases, hematite (α-Fe2O3) and maghemite (γ-Fe2O3), and characterize their magnetic field-driven self-assembly. We demonstrate that the relative amount of the two phases can be adjusted in a continuous way by varying the reaction time during the synthesis, leading to...

Université de Fribourg

Effective interactions between soft-repulsive colloids: Experiments, theory, and simulations

Mohanty, Priti S. ; Paloli, Divya ; Crassous, Jérôme J. ; Zaccarelli, Emanuela ; Schurtenberger, Peter

In: The Journal of Chemical Physics, 2014, vol. 140, no. 9, p. 094901

We describe a combined experimental, theoretical, and simulation study of the structural correlations between cross-linked highly monodisperse and swollen Poly(N-isopropylacrylamide) microgel dispersions in the fluid phase in order to obtain the effective pair-interaction potential between the microgels. The density-dependent experimental pair distribution functions g(r)’s are deduced from real...

Université de Fribourg

Quantifying the reversible association of thermosensitive nanoparticles

Zaccone, Alessio ; Crassous, Jérôme J. ; Béri, Benjamin ; Ballauff, Matthias

In: Physics Review Letters, 2011, vol. 107, no. 16, p. 168303

Under many conditions, biomolecules and nanoparticles associate by means of attractive bonds, due to hydrophobic attraction. Extracting the microscopic association or dissociation rates from experimental data is complicated by the dissociation events and by the sensitivity of the binding force to temperature (T). Here we introduce a theoretical model that combined with light-scattering...

Université de Fribourg

Crystallization-induced aggregation of block copolymer micelles: influence of crystallization kinetics on morphology

Mihut, Adriana M. ; Crassous, Jérôme J. ; Schmalz, Holger ; Ballauff, Matthias

In: Colloid & Polymer Science, 2010, vol. 288, no. 5, p. 573-578

We present a systematic investigation of the crystallization and aggregation behavior of a poly(1,2-butadiene)-block-poly(ethylene oxide) diblock copolymer (PB-b-PEO) in n-heptane. n-Heptane is a poor solvent for PEO and at 70°C the block copolymer self-assembles into spherical micelles composed of a liquid PEO core and a soluble PB corona. Time- and...