How nanoscale surface physics affects emergent material properties in colloidal suspensions

ORAL  · Invited

Abstract

Two colloidal suspensions of paucidisperse, spherical silica particles with different surface chemistries leading to extreme limits of surface contact friction are studied to identify experimental differences in shear rheology and microstructure and quantitatively test theory and simulation models. The non-equilibrium microstructure in the plane of shear is measured by flow-Small Angle Neutron Scattering (SANS) for steady shear states spanning the shear thinning and shear thickening regimes. The shear rheology and microstructure are compared against predictions from theory for Brownian hard sphere suspensions and state-of-the-art simulation methods that incorporate either contact friction or enhanced lubrication hydrodynamics. The first normal stress differences are confirmed to distinguish between these micromechanical mechanisms.  The differences in shear-induced microstructures between suspensions with varying contact friction demonstrate that the nonequilibrium microstructure can distinguish between nanotribological interactions in the shear thickened state.  Implications for the development of theories for colloidal suspension rheology are discussed.

*The Chemours Company, and the National Institute of Standards and Technology, U.S. Department of Commerce, in providing the neutron research facilities used in this work. This manuscript was prepared under Cooperative Agreement Nos. 370NANB17H302 from the National Institute of Standards and Technology (NIST), U.S. Department of Commerce. We also acknowledge the support of the National Institute of Standards and Technology, U.S. Department of Commerce, in providing the neutron research facilities used in this work. This work utilized facilities supported in part by the National Science Foundation under Agreement No. DMR-0944772. The statements, findings, conclusions and recommendations are those of the authors and do not necessarily reflect the view of NIST or the U.S. Department of Commerce.

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Publication: Yu-FanLee, YiminLuo, TianyiBai, C. Velez, S.C. Brown, and N.J. Wagner, "Microstructure and rheology of shear-thickening colloidal suspensions with varying interparticle friction: Comparison of experiment with theory and simulation models," Physics of Fluids 33, 033316 (2021).
Lee, Y.F., Y.M. Luo, S.C. Brown, and N.J. Wagner, "Experimental test of a frictional contact model for shear thickening in concentrated colloidal suspensions," Journal of Rheology 64, 267-282 (2020).

Presenters

  • Norman J Wagner

    • University of Delaware

Authors

  • Norman J Wagner

    • University of Delaware

  • Yu-Fan Lee

    • University of Delaware

  • Scott C Brown

    • Chemours