Paper Number
GG26 

Session
Rheology of Gels, Glasses and Jammed Systems

Title
Leveraging the polymer glass transition to access thermally-switchable shear jamming suspensions

Presentation Date and Time
October 11, 2022 (Tuesday) 2:10

Track / Room
Track 3 / Sheraton 5

Authors (Click on name to view author profile)

1. Chen, Chuqiao (University of Chicago, Pritzker School of Molecular Engineering)
2. van der Naald, Michael (University of Chicago, Department of Physics)
3. Singh, Abhinendra (The University of Chicago)
4. Dolinski, Neil (University of Chicago)
5. Jackson, Grayson L. (University of Chicago, James Franck Institute)
6. Jaeger, Heinrich M. (The University of Chicago, Department of Physics)
7. Rowan, Stuart J. (The University of Chicago, Pritzker School of Molecular Engineering)
8. de Pablo, Juan J. (The University of Chicago, Pritzker School of Molecular Engineering)

Author and Affiliation Lines (in printed abstract book)
Chuqiao Chen¹, Michael van der Naald², Abhinendra Singh³, Neil Dolinski³, Grayson L. Jackson⁴, Heinrich M. Jaeger², Stuart J. Rowan¹ and Juan J. de Pablo^1
1Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637; ²Department of Physics, University of Chicago, Chicago, IL 60637; ³The University of Chicago, Chicago, IL; ⁴James Franck Institute, University of Chicago, Chicago, IL 60637

Speaker / Presenter 
Chen, Chuqiao

Keywords
glasses; jammed systems; suspensions

Text of Abstract
When sheared sufficiently strongly, suspensions having a large volume fraction of solid particles can exhibit a dramatic increase in viscosity (shear thickening) and even solidify (shear jamming). The dramatic shear thickening is undesirable in suspension processing, yet it can also be leveraged in a range of applications, including personal protective wear and damping systems. To date, many shear jamming studies are based on suspensions of polymeric particles, yet almost all previous reports have been carried out under conditions that the particles are in a glassy state (e.g. polystyrene or PMMA particles at ambient conditions and far below T_g). While one expects that polymer glass transition T_g can dramatically affect the interparticle contact forces which are vital to dense suspension rheology, the effect of T_g has not been systematically studied in dense suspensions to date. In this work, we have designed suspensions consisting of crosslinked microparticles with accessible T_gs and studied the rheology at the vicinity of glass transition. We demonstrate that transitioning through T_g of polymer particles has a dramatic and non-monotonic effect on shear thickening and the shear jamming transition can be turned on or off in situ by varying the temperature relative to T_g. This behavior is attributed to the significant change in mechanical stiffness as well as the inter-particle surface friction near T_g. This study lays the groundwork for switchable jamming systems and motivates further research to investigate how polymer dynamics at the interface can affect the constraints on particle relative motions.