Paper Number
SC3 

Session
Suspensions and Colloids

Title
Emergence of piezoelectric response by friction in shear thickening dense suspension

Presentation Date and Time
October 10, 2022 (Monday) 10:30

Track / Room
Track 1 / Sheraton 4

Authors (Click on name to view author profile)

  1. Kim, Hojin (The University of Chicago, Pritzker School of Molecular Engineering)
  2. Rowan, Stuart J. (The University of Chicago, Pritzker School of Molecular Engineering)
  3. Jaeger, Heinrich M. (The University of Chicago, Department of Physics)

Author and Affiliation Lines (in printed abstract book)
Hojin Kim1, Stuart J. Rowan1 and Heinrich M. Jaeger2
1Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL 60637; 2Department of Physics, The University of Chicago, Chicago, IL 60637

Speaker / Presenter 
Kim, Hojin

Keywords
experimental methods; colloids; suspensions

Text of Abstract
Control of frictional contacts driven by interparticle constraints has been widely studied to tailor shear thickening behavior of dense colloidal suspensions. However, direct evidence of frictional contacts is still lacking due to the technical difficulties in detecting their formation during shear in-situ. By simultaneous measurements of viscosity and conductance in dense suspensions of piezoelectric particles, we found that piezoelectricity arises from stress-activated interparticle friction along with the shear thickening. This observation suggests clear evidence of frictional contact formation in the shear thickening regime. The role of frictional contacts was further explored by varying the degree of thickening, from continuous to discontinuous, with particle volume fraction and shape. The measured conductance showed that the emergence of frictional contact is a stress-driven phenomenon, whereas the shear-thickening begins at a constant strain amplitude. The friction-driven piezoelectric response can furthermore serve as direct signature of the spatiotemporal reconfiguration of particles under oscillatory shear. Importantly, stress-dependent frictional contact formation suggests new possibilities for biomechanically adaptive materials using mechano-activated “click” chemistries that operate with a specific, targeted stress and frequency.