title: Structural regime identification in ionotropic alginate gels: influence of the cation nature and alginate structure.
abstract: The morphologies of several ionotropic alginate hydrogels and aerogels were investigated by SAXS according to the nature of the divalent metal cation (Mn(2+), Co(2+), Zn(2+), Cu(2+)) and the guluronic fraction of the alginate. All alginate hydrogel and aerogel samples show isotropic small-angle X-ray scattering. Gelation results from cooperative associations of cations and chain segments and yields different nanostructures, that is, nanofibrillar morphology or multiple junction morphology, according to cation type and eventually mannuronic/guluronic ratio. Therefore, Mn and Cu gels present the same morphology whatever the guluronic ratio, whereas Co and Zn gels yield different nanostructures. In the size range investigated by SAXS (~10-200 Å), the structure of aerogels obtained by CO(2) supercritical drying is found to be inherited from the morphology of the parent hydrogel whatever the initial structural regime.
authors.affiliation: Institut Charles Gerhardt Montpellier, UMR 5253 CNRS-UM2-ENSCM-UM1, Matériaux Avancés pour la Catalyse et la Santé, ENSCM, 8 rue de l'Ecole Normale, 34296 Montpellier cedex 5, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Agulhon
authors.forename: Mike
authors.initials: M
authors.lastname: Robitzer
authors.forename: Laurent
authors.initials: L
authors.lastname: David
authors.forename: Françoise
authors.initials: F
authors.lastname: Quignard
mesh_terms: D000464:Alginates / Q000737:chemistry* / Q000648:ultrastructure; D002413:Cations, Divalent; D005782:Gels / Q000737:chemistry; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D008670:Metals / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure*; D053838:Scattering, Small Angle; D014961:X-Ray Diffraction
chemical_list: D000464:Alginates; D002413:Cations, Divalent; D005782:Gels; D006603:Hexuronic Acids; D008670:Metals; D020723:Glucuronic Acid