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(83) Production(s) de STOCCO A.
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Rotational diffusion of partially wetted colloids at fluid interfaces
Auteur(s): Stocco A., Chollet B., Wang X., Blanc C., Nobili M.
(Article) Publié:
Journal Of Colloid And Interface Science, vol. 542 p.363-369 (2019)
Texte intégral en Openaccess :
Ref HAL: hal-02024615_v1
DOI: 10.1016/j.jcis.2019.02.017
WoS: 000461536400040
Exporter : BibTex | endNote
10 Citations
Résumé: Hypothesis: Rotational Brownian diffusions of colloidal particles at a fluid interface play important roles in particle self-assembly and in surface microrheology. Recent experiments on translational Brownian motion of spherical particles at the air-water interface show a significant slowing down of the translational diffusion with respect to the hydrodynamic predictions (Boniello et al., 2015). For the rotational diffusions of partially wetted colloids, slowing down of the particle dynamics can be also expected.Experiments: Here, the rotational dynamics of Janus colloids at the air-water interface have been experimentally investigated using optical microscopy. Bright field and fluorescent microscopies have been used to measure the in-plane and out-of-plane particle rotational diffusions exploiting the Janus geometry of the colloids we fabricated.Findings: Our results show a severe slowing down of the rotational diffusion Dr,⊥ connected to the contact line motion and wetting-dewetting dynamics occurring on particle regions located at opposite liquid wedges. A slowing down of the particle rotational diffusion about an axis parallel to the interfacial normal Dr,|| was also observed. Contact line fluctuations due to partial wetting dynamics lead to a rotational line friction that we have modelled in order to describe our results.
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Central Role of Bicarbonate Anions in Charging Water/Hydrophobic Interfaces
Auteur(s): Yan Xibo, Delgado Marco, Aubry Julien, Gribelin Olivier, Stocco A., Boisson-da Cruz Fernande, Bernard Julien, Ganachaud Francois
(Article) Publié:
Journal Of Physical Chemistry Letters, vol. 9 p.96-103 (2018)
Texte intégral en Openaccess :
Ref HAL: hal-02010370_v1
DOI: 10.1021/acs.jpclett.7b02993
WoS: 000419750900016
Exporter : BibTex | endNote
16 Citations
Résumé: Aqueous interfaces are ubiquitous in Nature and play a fundamental role in environmental or biological processes or modern nanotechnologies. These interfaces are negatively charged, and despite several decades of research, the rationale behind this phenomenon is still under debate. Two main controversial schools of thought argue on this issue; the first relies on the adsorption of hydroxide anions on hydrophobic surfaces, whereas the second one supports a self-rearrangement of water molecules at the interface bearing hydronium ions. Here, we report on two series of independent experimental studies (nanoprecipitation and interfacial tension measurements) that demonstrate that in the pH 5–10 range the negative interfacial charge of the colloids mostly stems from bicarbonate ions, whereas at lower and higher pH, protons and hydroxide ions contribute, with bicarbonate ions, to the interfacial charging. This new interpretation complies with previous studies and opens new perspectives to this striking physical chemical issue.
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Active Colloids confined at the gas-liquid interface
Auteur(s): Stocco A.
Conference: Liquid @ Interfaces (Bordeaux, FR, 2018-10-22)
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Thermodynamics of interfaces
Auteur(s): Stocco A.
Conference: Thermodynamics and energetics of soft matter systems - Summer school (Grenoble, FR, 2018-07-24)
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Coupled Convective Instabilities: Autonomous Motion and Deformation of an Oil Drop on a Liquid Surface
Auteur(s): Pimienta Véronique, Stocco A., Wodlei F., Antoine C.
Chapître d'ouvrage: Self-Organized Motion: Physicochemical Design Based On Nonlinear Dynamics, vol. p.63-89 (2018)
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