Paper Number
SC32 

Session
Suspensions and Colloids

Title
The mechanics of particle bonds and the elastic modulus of cluster gels

Presentation Date and Time
October 14, 2015 (Wednesday) 10:25

Track / Room
Track 1 / Constellation C

Authors (Click on name to view author profile)

1. Furst, Eric M. (University of Delaware, Department of Chemical and Biomolecular Engineering)
2. Whitaker, Kathryn A. (University of Delaware, Department of Chemical and Biomolecular Engineering)

Author and Affiliation Lines (in printed abstract book)
Eric M. Furst and Kathryn A. Whitaker
Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716

Speaker / Presenter 
Furst, Eric M.

Text of Abstract
The rheology and stability of colloidal depletion gels affects the applications and shelf-life of materials and products ranging from paints, foods, and personal care products to pharmaceuticals and agrochemicals. Processes occur over multiple length scales that contribute to the rheology of gels, including their elastic modulus and yield stress. These processes include the nanometer-scale colloidal interactions of “bonds” that stretch and rupture to the formation, deformation, and break-up of percolating micro-structures throughout the material. In this talk, I will discuss the direct measurement of the colloidal forces that constitute the rupturing of the physical bonds between particles in a gel. Thermal rupture force distributions are measured by averaging many approach and retraction bond rupturing cycles between pairs of particles [1]. By connecting these bond-level mechanics to the bulk rheology to in a single model depletion gel material [2], we gain unique insight into the relationship between non-equilibrium gel states, the underlying phase behavior of colloidal suspensions, and the mesoscale mechanics that ultimately govern the elasticity and breakup of colloidal depletion gels.

[1] Swan, J.; Shindel, M.; Furst, E. M. Measuring Thermal Rupture Force Distributions from an Ensemble of Trajectories. Phys. Rev. Lett. 2012, 109, 198302. [2] Hsiao, L. C.; Solomon, M. J.; Whitaker, K. A.; Furst, E. M. A Model Colloidal Gel for Coordinated Measurements of Force, Structure, and Rheology. J. Rheology, 2014, 58, 1485–1504.