Microstructure in Gelling Systems

The rheology of colloidal gels arises from how the ramified network structure responds to an applied stress. Stress transmission is controlled by the topology of the microstructure and the nature of the interparticle “bonds” between colloids. Thus, to deform a gel, these bonds must stretch to accommodate extension and compression of the microstructure.

This project focused on developing and refining a model experimental system to directly and quantitatively measure gels over multiple lengthscales, including the “bond” mechanics, microstructure and bulk rheology. This work was performed in close collaboration with Professor Michael Solomon, University of Michigan. This report summarizes the development of the model system to achieve individual bond rupture measurements and the validation of bond rupture measurements by a dynamical model of bond rupture. We conclude with a comparison of the experimental gel modulus to the modulus predicted by current theory and an energy balance model.