"From shrimp shells to smart materials: shaping polysaccharides into responsive assemblies and coatings"
Conférence "From shrimp shells to smart materials: shaping polysaccharides into responsive assemblies and coatings", de Leonardo Chiappisi, Institut Laue-Langevin, Grenoble, France, organisée par l'Institut Charles Sadron
Abstract:
Polysaccharides constitute an important, renewable and abundant resource with unique characteristics. The amphiphilic nature of the saccharidic units, the large number of possible hydrogen bonds, and the stiffness of the polymeric backbone make their self- and co-assembly with other colloidal particles an intriguing topic. The above-mentioned properties, for instance, strongly affect the ionic co-assembly of charged polysaccharide with oppositely charged macroions (surfactant micelles, proteins, etc).
Herein, the co-assembly behavior of the cationic polysaccharide, chitosan, and weakly anionic, alkyl oligo ethylene oxide carboxylic acid (CiEj-CH2COOH) micelles and vesicles is presented. These compounds co-assemble into strikingly different structures, depending on the molecular architecture of the surfactant, i.e. the number of ethylene oxide units and the alkyl chain length. Besides their exceptionally large structural variety, the complexes can react strongly to minor changes of solution acidity or hydrostatic pressure. A deep understanding of the complex behavior of such systems requires a combination of several techniques: small-angle neutron scattering, neutron spin-echo, and neutron reflectometry are complemented with on- and off-line techniques, such as static and dynamic light scattering, optical ellipsometry, densitometry or cryo-electron microscopy. In summary, the combination of different techniques provides a comprehensive understanding of the polysaccharide/surfactant co-assembly process, which serves as the basis for the development of applications in very different fields.
Les personnes souhaitant rencontrer Leonardo Chiappisi sont priées de prendre contact avec Thierry Charitat (tel. 03 88 41 40 05 ou mail thierry.charitat@unistra.fr)
