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Matière Molle
(423) Articles dans des revues
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Hidden traces of chirality in the fluctuations of a fully unwound cholesteric ![doi link](plugins/aigle//images/ext_link.jpg)
Auteur(s): Poy G.
(Article) Publié:
Soft Matter, vol. 19 p.1115-1130 (2023)
Texte intégral en Openaccess :
Ref HAL: hal-03953472_v1
DOI: 10.1039/D2SM01646J
Exporter : BibTex | endNote
Résumé: Confinement and hydrodynamic interactions often play an important role in the fluctuation dynamics of soft matter systems, which can typically be studied using light scattering techniques. With experimental and theoretical methodologies, I demonstrate here that chirality is an additional critical parameter that leads to diverging decay times and correlation lengths in chiral liquid crystal cells with a fully unwound cholesteric helix. This study combines light scattering measurements made in a tailored microscope geometry and theoretical calculations of the decay dynamics of chiral orientational fluctuations---including hydrodynamics---to establish the existence of two soft chiral modes of fluctuations driving the destabilization of the unwound cholesteric. Despite the achirality of the equilibrium state of unwound cholesterics, this study indicates that chirality hides itself in the orientational fluctuation modes and plays a major role in their dynamics, which can be exploited to locally measure the strength of chirality in frustrated chiral liquid crystal cells.
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Transfer of multi-DNA patches by colloidal stamping ![doi link](plugins/aigle//images/ext_link.jpg)
Auteur(s): Khalaf Rawan, Viamonte Andrea, Ducrot Etienne, Merindol R. , Ravaine Serge
(Article) Publié:
Nanoscale, vol. 15 p.573-577 (2023)
Texte intégral en Openaccess : ![arxiv](plugins/aigle//images/logo-arxiv.png)
Ref HAL: hal-03932109_v1
Ref Arxiv: 2301.05515
DOI: 10.1039/d2nr05016a
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: Patchy particles have received great attention due to their ability to develop directional and selective interactions and serve as building units for the self-assembly of innovative colloidal molecules and crystalline structures. Although synthesizing particles with multiple dissimilar patches is still highly challenging and lacks efficient methods, these building blocks would open paths towards a broader range of ordered materials with inherent properties. Herein, we describe a new approach to pattern functional DNA patches at the surface of particles, by the use of colloidal stamps. DNA inks are transferred only at the contact zones between the target particles and the stamps thanks to selective strand-displacement reactions. The produced DNA-patchy particles are ideal candidates to act as advanced precision/designer building blocks to self-assemble the next generation of colloidal materials.
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Recent scattering approaches to structure and dynamics of polymer nanocomposites ![doi link](plugins/aigle//images/ext_link.jpg)
Auteur(s): Kruteva M., Genix A.-C., Holderer O., Oberdisse J.
(Article) Publié:
Frontiers In Soft Matter, vol. 2 p.992563 (2022)
Ref HAL: hal-04244916_v1
DOI: 10.3389/frsfm.2022.992563
Exporter : BibTex | endNote
Résumé: The characterization of polymer nanocomposites on molecular length scales and timescales is a challenging task, which is also indispensable for the understanding of macroscopic material's properties. Neutron scattering is one of the techniques which are very well-suited for studying the structure and molecular motion in such soft matter systems. X-rays can also be used for the same purpose, however, with higher energy and thus a different focus on dynamics, where they are better suited for nanoparticle motion. In this mini-review, we aim at highlighting recent results in the field of polymer nanocomposites, including nanoparticle structure in various experimental systems, from model to industrial, and polymer and particle dynamics. This allows establishing the link between microscopic and macroscopic properties, in particular rheology.
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Kitchen flows: Making science more accessible,affordable, and curiosity driven ![doi link](plugins/aigle//images/ext_link.jpg)
Auteur(s): Fuller Gerald G., Lisicki Maciej, Mathijssen Arnold J. T. M., Mossige Endre J. L., Pasquino Rossana, Prakash Vivek N., Ramos L.
(Article) Publié:
Physics Of Fluids, vol. 34 p.110401 (2022)
Texte intégral en Openaccess : ![openaccess](plugins/aigle//images/logo-openaccess.png)
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Exploiting the lower disorder-to-order temperature in polystyrene-b-poly(n-butyl acrylate)-b-polystyrene triblock copolymers to increase their flow resistance at high temperature ![doi link](plugins/aigle//images/ext_link.jpg)
Auteur(s): Coutouly Clement, Van ruymbeke Evelyne, Ramos L., Dieudonne-George P., Fustin Charles-andre
(Article) Publié:
Journal Of Rheology / Transactions Of The Society Of Rheology; Society Of Rheology -- Transactions, vol. 66 p.1305-1318 (2022)
Texte intégral en Openaccess :
DOI: 10.1122/8.0000506
WoS: WOS:000886063900025
Résumé: This work focuses on the temperature-dependent structural and rheological characterization of polystyrene-b-poly(n-butyl acrylate)-b-polystyrene
triblock copolymers (PS-b-PnBA-b-PS) in the melt and, in particular, on their ability to show a lower disorder-to-order temperature
(LDOT). To this aim, copolymers of varying block lengths, but keeping the PnBA block as a major component, were synthesized. Smallangle
x-ray scattering revealed that the copolymers with short PS blocks (∼10 kg/mol) approach an LDOT but do not cross it. At room temperature,
these copolymers exhibit higher moduli compared to a PnBA homopolymer due to the reinforcing effect of the PS but are flowing
at temperatures above the glass transition of the PS. Increasing the PS and PnBA block length, to keep the same PS fraction, induces more
profound changes in the structural and viscoelastic behaviors. Such a copolymer crosses the LDOT, leading to a microphase-separated and
ordered state at high temperature. Contrary to the copolymers with short PS blocks, the flow regime was not reached, even at temperatures
well above the glass transition of the PS. Instead, a low-frequency plateau was observed in rheology, showing the increased lifetime of the
microphase-separated PS domains. ABA triblock copolymers exhibiting an LDOT behavior could, thus, be of interest for the design of thermoplastic
elastomers or pressure-sensitive adhesives that can resist the flow at high temperatures
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Fast and pure phase-shifting off-axis holographic microscopy with a digital micromirror device ![doi link](plugins/aigle//images/ext_link.jpg)
Auteur(s): Brodoline A., Alexandre D., Gross M.
(Article) Publié:
Applied Optics, vol. 61 p.4296-4302 (2022)
Texte intégral en Openaccess :
Ref HAL: hal-03835417_v1
DOI: 10.1364/ao.452382
Exporter : BibTex | endNote
Résumé: We present a phase-shifting digital holographic microscopy technique, where a digital micromirror device enables to perform a precise phase-only shift of the reference wave. By coupling the beam into a monomode fiber, we obtain a laser mode with a constant phase shift, equally acting on all pixels of the hologram. This method has the advantage of being relatively simple and compatible with high frame rate cameras, which makes it of great interest for the observation of fast phenomena. We demonstrate the validity of the technique in an off-axis configuration by imaging living paramecia caudata.
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Impact of structural flexibility in the adsorption of wheat and sunflower proteins at an air/water interface ![doi link](plugins/aigle//images/ext_link.jpg)
Auteur(s): Poirier A., Banc A., Kapel Romain, In M., Stocco A., Ramos L.
(Article) Publié:
Colloids And Surfaces A: Physicochemical And Engineering Aspects, vol. 648 p.129317 (2022)
Texte intégral en Openaccess :
Ref HAL: hal-03686739_v1
DOI: 10.1016/j.colsurfa.2022.129317
WoS: WOS:000808543400003
Exporter : BibTex | endNote
Résumé: Food transition requires the replacement in human diet of animal-based proteins by alternative sources of proteins including plant-based proteins. This calls for a detailed knowledge of the functional properties of plant-based proteins, including their surface activity. In this framework, we provide here a comparative study of the interfacial properties of two plant proteins, extracted respectively from wheat and sunflower. We combine time- and concentration-dependent measurements of the surface tension and the surface rheology, as measured with a pendant-drop set-up, and of the surface excess concentration, as measured by ellipsometry, of plant protein interfacial films. We demonstrate a time-concentration superposition principle for the surface pressure and surface excess concentration, showing that the kinetics for the building of the interfacial films is essentially governed by the diffusion of the proteins from the bulk to the interface. We find that the rheological and structural properties of the interfacial protein films show markedly different behaviors for the two classes of protein, which is encoded in the structural features of the individual proteins: wheat proteins are more surface active than sunflower proteins, are keen to compress and re-arrange at an air-water interface, whereas sunflower proteins do not. This work provides qualitative and quantitative analysis of the comparative interfacial behavior of flexible and rigid plant proteins extracted respectively from wheat and sunflower, and demonstrates that a combination of several experimental techniques is necessary to obtain insightful information on the interfacial properties of any species.
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