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Polymer-silica interactions: from structure to mechanical reinforcement of hybrid hydrogels
Séverine Rose, doctorante - PhD student Crédits : ESPCI ParisTechWe are investigating the consequences of the introduction of inorganic nanoparticles in a polymer hydrogel. The specific interactions existing between poly(N,N-dimethylacrylamide) and silica nanoparticles are at the origin of a strong mechanical reinforcement in terms of stiffness and strain at failure. Indeed, the impact of silica nanoparticles onto the general characteristics of hydrogels has been investigated in terms of structural, thermodynamical and mechanical properties. The study of the mechanical properties of hybrid hydrogels has been conducted in details with a special focus on PDMA/silica interactions at different strains and probing the time-scale effects. A strong time-dependence has been evidenced and a brief modelling of the hybrid structure has been proposed, taking into account the viscoelastic nature of the system. The behaviour of these hybrid hydrogels can be described as double networks. The PDMA/silica specific interaction has also been studied by light scattering experiments, evidencing several dynamics. We show that the general reinforcement can be controlled by the dynamics of the PDMA/silica association.
Key words: hybrid hydrogels, silica nanoparticles, specific interactions, mechanical reinforcement, light scattering, neutron scattering.