Hierarchical cross-linking in physical alginate gels: a rheological and dynamic light scattering investigation Auteur(s): Larobina Domenico, Cipelletti L. (Article) Publié: Soft Matter, vol. p.10005-10015 (2013) Texte intégral en Openaccess : Ref HAL: hal-00874406_v1 Ref Arxiv: 1309.6349 DOI: 10.1039/c3sm52006d WoS: 000325726100007 Ref. & Cit.: NASA ADS Exporter : BibTex | endNote 31 Citations Résumé: We investigate the dynamics of alginate gels, an important class of biopolymer-based viscoelastic materials, by combining mechanical tests and non-conventional, time-resolved light scattering methods. Two relaxation modes are observed upon applying a compressive or shear stress. Dynamic light scattering and diffusive wave spectroscopy measurements reveal that these modes are associated with discontinuous rearrangement events that restructure the gel network via anomalous, non-diffusive microscopic dynamics. We show that these dynamics are due to both thermal activation and internal stress stored during gelation and propose a scenario where a hierarchy of cross-links with different life times is responsible for the observed complex behavior. Measurements at various temperatures and sample ages are presented to support this scenario. |