(265b) Non-Linear Rheology and Fracture in Alginate Hydrogels

Polysaccharide networks are widely used in biomedical and food applications. In this presentation, results on alginate hydrogels, a model polysaccharide network, will be presented. Effect of two different types of crosslinking, ionic and covalent, on the mechanical properties will be reported. Calcium salts have been used to obtain ionically crosslinked gels. Diamines and amine functionalized carbon nanodots have been used to synthesizing covalently crosslinked gels. Alginate gels with carbon nanodots display photoluminescent behavior, when excited with an UV light of 365 nm. Small angle x-ray scattering was used to capture the structural differences in ionic and covalently crosslinked gels. Shear rheology data capture strain stiffening behavior for these gels. In addition, negative normal stress has been captured, which has not been reported earlier for any polysaccharide networks. Cavitation rheology technique was used to capture the failure behavior of these gels and the results indicate distinctly different behavior for the ionic and covalently crosslinked gels. The results presented here provide new understanding of the deformation behavior of alginate hydrogels.