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Théorie-Modélisation-Simulation-Calculs à l'IRaMiS


2013 | Prix Louis D. à Thibault Cantat.
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2013 | STM et AFM : Molécules, photons et microscopies à sonde locale.
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Dossier multimédia "nanosciences" du CEA

 

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Jeudi 24/07/2014, 11h00-12h00
Séminaire LIONS
Sara Bals

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Les dépêches [+]
Soutenance HDR de Sébastien Aumaître 

Sébastien Aumaître (groupe SPHYNX) soutiendra sa thèse d'habilitation à diriger les recherches, intitulée « Fluctuations et instabilités dans les systèmes hors-équilibre », le mardi 22 juillet à 10h, à l'amphi Bloch. Vous êtes cordialement invités à la soutenance ainsi qu'au pot qui suivra.

 
G. Fleury, dépêche du 07/07/2014

 

Cellulose Nanofibril-Based Multilayered Thin Films: Effect of Ionic Strength on Porosity, Swelling, and Optical Properties 

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Firas Azzam, Céline Moreau, Fabrice Cousin, Alain Menelle, Herve Bizot, and Bernard Cathala

TEMPO-oxidized cellulose nanofibrils (CNF) and synthetic poly(allylamine) hydrochloride (PAH) were used to build multilayered thin films via the dipping-assisted layer-by-layer technique. We used the ionic strength, in both CNF suspension and PAH solution, as a key parameter to control the structure of the films. Three systems with different ionic strength parameters were investigated. We studied the growth of the films and their surface morphology by ellipsometry and AFM and investigated their porosity and swelling behavior using neutron reflectivity. Our results showed that the PAH conformation is a determining factor not only for film growth but also for structural properties: with salt-free PAH solution where chains have extended conformation, the resulting films have lower porosity and higher swelling ratios, compared to the ones made using high ionic strength (1 M) PAH solution, where chains have a coiled conformation. The slight aggregation of CNF, induced by adding a small amount of salt (12 mM), has less influence on film growth and porosity, whereas it has a greater impact on swelling. The origin of these differences is discussed. The structure of the films obtained was linked to their optical properties and, in particular, to their antireflective character.

A. Menelle, dépêche du 30/06/2014

 

 

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