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Jamming, plasticité et défaillance des matériaux
(9) Production(s) de l'année 2023
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Gelation and Re-entrance in Mixtures of Soft Colloids and Linear Polymers of Equal Size 
Auteur(s): Parisi Daniele, Truzzolillo D., Slim Ali, Dieudonne-George P., Narayanan Suresh, Conrad Jacinta, Deepak Vishnu, Gauthier Mario, Vlassopoulos Dimitris
(Article) Publié:
Macromolecules, vol. 56 p.1818-1827 (2023)
Texte intégral en Openaccess : 
Ref HAL: hal-04035012_v1
Ref Arxiv: 2212.05992
DOI: 10.1021/acs.macromol.2c02491
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: Liquid mixtures composed of colloidal particles and much smaller non-adsorbing linear homopolymers can undergo a gelation transition due to polymer-mediated depletion forces. We now show that the addition of linear polymers to suspensions of soft colloids having the same hydrodynamic size yields a liquid-to-gel-to-re-entrant liquid transition. In particular, the dynamic state diagram of 1,4-polybutadiene star–linear polymer mixtures was determined with the help of linear viscoelastic and small-angle X-ray scattering experiments. While keeping the star polymers below their nominal overlap concentration, a gel was formed upon increasing the linear polymer content. Further addition of linear chains yielded a re-entrant liquid. This unexpected behavior was rationalized by the interplay of three possible phenomena: (i) depletion interactions, driven by the size disparity between the stars and the polymer length scale which is the mesh size of its entanglement network; (ii) colloidal deswelling due to the increased osmotic pressure exerted onto the stars; and (iii) a concomitant progressive suppression of the depletion efficiency on increasing the polymer concentration due to reduced mesh size, hence a smaller range of attraction. Our results unveil an exciting new way to tailor the flow of soft colloids and highlight a largely unexplored path to engineer soft colloidal mixtures.
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Transfer of multi-DNA patches by colloidal stamping
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 :
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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