title: Influence of both cation and alginate nature on the rheological behavior of transition metal alginate gels.
abstract: The rheological properties of several ionotropic alginate hydrogels were investigated according to the nature of the divalent cation (Mn(2+), Co(2+), Cu(2+)) and the guluronic fraction of the alginate (HG and LG for "high G-content" and "low G-content"). Six hydrogels (Mn-LG, Mn-HG, Co-LG, Co-HG, Cu-LG and Cu-HG) were synthesized and studied by spectromechanical analyses. On one hand, Cu-HG, Cu-LG and Co-HG behaved as viscoelastic solids: the elastic contribution was higher than the dissipative component in all the frequency range studied (G'>G"). No flow zone (G">G') was detected even at very low values of the shearing frequency. On the other, Mn-HG, Mn-LG and Co-LG presented a spectromechanical behavior that resembled that observed classically for entangled polymers. Indeed, at high frequency, these latter materials could be compared to a viscoelastic solid but at low frequency, the flow zone was described and the viscous character became prevalent with finite relaxation time. Very good correlations with the microscopic structurations of the network were evidenced (rubbery vs. flow zone and fibrillar vs. complex morphology respectively).
authors.affiliation: Institut Charles Gerhardt Montpellier UMR 5253 CNRS-UMII-ENSCM-UMI, Équipe Matériaux Avancés pour la Catalyse et la Santé, 8 rue de l'École Normale, 34296 Montpellier Cedex 5, France. Electronic address: pierre.aguhlon@enscm.fr.
authors.forename: Pierre
authors.initials: P
authors.lastname: Agulhon
authors.affiliation: Institut Charles Gerhardt Montpellier UMR 5253 CNRS-UMII-ENSCM-UMI, Équipe Matériaux Avancés pour la Catalyse et la Santé, 8 rue de l'École Normale, 34296 Montpellier Cedex 5, France. Electronic address: mike.robitzer@enscm.fr.
authors.forename: Mike
authors.initials: M
authors.lastname: Robitzer
authors.affiliation: Institut Charles Gerhardt Montpellier UMR 5253 CNRS-UMII-ENSCM-UMI, Equipe Ingénierie et Architectures Macromoléculaires, Université Montpellier II, Place Eugène Bataillon, CC 17002, 34095 Montpellier Cedex 5, France. Electronic address: jean-pierre.habas@univ-montp2.fr.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Habas
authors.affiliation: Institut Charles Gerhardt Montpellier UMR 5253 CNRS-UMII-ENSCM-UMI, Équipe Matériaux Avancés pour la Catalyse et la Santé, 8 rue de l'École Normale, 34296 Montpellier Cedex 5, France. Electronic address: francoise.quignard@enscm.fr.
authors.forename: Françoise
authors.initials: F
authors.lastname: Quignard
mesh_terms: D000464:Alginates / Q000737:chemistry*; D002412:Cations; D003035:Cobalt / Q000737:chemistry; D003300:Copper / Q000737:chemistry; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D020100:Hydrogels / Q000737:chemistry*; D008345:Manganese / Q000737:chemistry; D012212:Rheology / Q000379:methods*
chemical_list: D000464:Alginates; D002412:Cations; D006603:Hexuronic Acids; D020100:Hydrogels; D003035:Cobalt; D008345:Manganese; D003300:Copper; D020723:Glucuronic Acid
keywords: Alginate; Hydrogels; Metallic cations; Relaxation time; Rheological properties; Spectromechanical behavior