Jeffrey Richards - 2026 Metzner Awardee

2026 Metzner Awardee
Chemical & Biological Engineering
Northwestern University

Biography

Dr. Richards received his PhD in August 2014 from the Department of Chemical Engineering at the University of Washington. After graduating from UW, he performed postdoctoral research at the University of Delaware and the NIST Center for Neutron Research in Gaithersburg, MD as a National Research Council Fellow. Dr. Richards joined the Chemical and Biological Engineering faculty at Northwestern in 2018 where his research focuses on engineering the electrical properties of soft materials for electrochemical energy storage applications. During his time at Northwestern, Dr. Richards received the National Science Foundation’s CAREER award, the American Chemical Society’s Distinguished New Investigator Award, and the 2023 Society of Rheology Publication Award.

Research Accomplishments

In 2011, a new technology, the semi-solid flow battery, emerged from a group at MIT that utilized a flowing suspension of granular and Brownian particles. Key to the function of this battery was the addition of a conductive additive, typically carbon black nanoparticles, that created an electrically percolated network under flow to supply electrons to the electrochemically active granular particles. While this technology showed promise as a low-cost, grid-scale battery storage system, many challenges stem from the coupling between the flow behavior and the electrical transport in these suspensions. Rheo-electric measurements emerged as a powerful tool to interrogate this coupling and reveal the underlying physics determinative of the rheological behavior of these complex suspensions and their electrical properties.

Motivated by this technology and the desire to interrogate the microscopic origin of electron transport in suspensions of carbon black, Richards built a Couette rheo-electric geometry capable of interrogating electrical properties under steady shear and capable of performing simultaneous neutron scattering measurements [1,2] to examine the evolving microstructure of these complex suspensions under flow. This Couette was compatible with an ARES-G2 rheometer set up for primitive instrument control with a Python interface to coordinate with rheo-electric and scattering data acquisition.

Richards’ collaborative work on understanding the rheology and electrical transport in carbon black suspensions with Norman Wagner and Julie Hipp at the University of Delaware during his postdoc redefined how we understood the rheology and electrical properties of these suspensions both in the quiescent state and under flow. Relevant publications are summarized below:

• “Clustering and Percolation in Suspensions of Carbon Black,” Langmuir 2017 [3]. By combining ultra-small angle neutron scattering with impedance spectroscopy, this work proved that mechanical and electrical percolation are independent from one another and electrical percolation arises from the dynamics of carbon black agglomerates which form the building blocks of the stress bearing bonds that give carbon black suspensions their yield stress. This disproved a prevailing view at the time which was that the stress bearing bonds (physical contacts) between carbon particles formed the conducting pathway for electrons.
• “Structure-property relationships of sheared carbon black suspensions determined by simultaneous rheological and neutron scattering measurements,” Journal of Rheology 2019 [4]. In this work, USANS measurements showed that the flow curve of a carbon black suspension could be divided into two regimes, a strong flow regime where the suspension is sheared at stresses well above the yield stress and a weak flow regime where the suspension exhibits stress equal to or less than the yield stress. This work proved that in the strong flow regime carbon black agglomerates break up self-similarly or at constant fractal dimension whereas in the weak flow regime shear-driven heterogeneities dominate the rheological response.
• “Direct measurements of the microstructural origin of shear-thinning in carbon black suspensions,” Journal of Rheology 2021 [5]. Following the prior work from 2019, this work provided direct experimental evidence that the self-similar break up of carbon black agglomerates could be predicted by the Mason number, the dimensionless ratio of the shear forces acting to breakup agglomerates to the cohesive forces holding them together.

While this collaborative work provided a strong microstructural basis for predicting suspension rheology, the electrical properties remained difficult to predict and understand. As Professor Richards began his faculty career at Northwestern, he developed new model systems to unveil for the first time the role that particle dynamics play in suspensions of conducting particles. Significant works and contributions are highlighted below.

• “Quantifying the hydrodynamic contribution to electrical transport in non-Brownian suspensions,” PNAS 2022 [6]. This work was a first of its kind contribution showing the electrical diffusivity is quantitatively predicted by shear drive self-diffusion, predicted by a new scaling law identified by Richards and validated by simulations from Jim Swan. At the time of this publication, there was no precedent for this new insight.
• “Quantifying electron transport in aggregated colloidal suspensions in the strong flow regime,” PNAS 2024 [7]. This work showed that the electrical diffusivity of carbon black suspensions could be predicted using the scaling law developed in the 2022 PNAS paper. Again, this non-intuitive result had no precedent at the time.

Richards continues to innovate in the field of electrically responsive suspensions by developing new synthesis strategies [8,9] to engineer colloidal dynamics to elicit unique mechano-electric transduction pathways, apply the physics of the fluid Mason number to predict the suspension rheology of battery slurry [10-12] and develop new tools to study responsive soft matter at the microscale and macroscale [13-15]. His future plans include revisiting engineering the colloidal physics of suspension electrodes for semi-solid flow batteries by chemically modifying the surface of carbon black for colloidal stability in electrochemically relevant environments.

Society Service

Richards has contributed significantly to society service by reviewing for the Journal of Rheology, Rheological Acta, and Macromolecules. He has served as a session chair at Society of Rheology Meetings and area 1J AIChE Annual Meeting. At the 2024 Society of Rheology meeting, Richards hosted a workshop on automated Rheo+ measurements whose attendees included both industry and academia. TA Instruments now sells a commercial rheo-electric accessory based on designs originating from his published work. In addition to the commercial accessory, Richards maintains a long standing collaboration with TA instruments to enable external control of their rheometers using script based programming. This allows rheological tests to be automated and synchronized with other measurements and is now available to broader rheology community.

1. Richards, J. J., Gagnon, C. V. L., Krzywon, J. R., Wagner, N. J., Butler, P. D. (2017). Dielectric RheoSANS — Simultaneous interrogation of impedance, rheology and small angle neutron scattering of complex fluids. Journal of Visualized Experiments, 2017(122), e55318–e55318. https://doi.org/10.3791/55318
2. Richards, J.J., Wagner, N. J., Butler, P. D. (2017). A strain-controlled RheoSANS instrument for the measurement of the microstructural, electrical, and mechanical properties of soft materials. Review of Scientific Instruments, 88(10). https://doi.org/10.1063/1.4986770
3. Richards, J. J., Hipp, J. B., Riley, J. K., Wagner, N. J., Butler, P. D. (2017). Clustering and Percolation in Suspensions of Carbon Black. Langmuir, 33(43), 12260–12266. https://doi.org/10.1021/acs.langmuir.7b02538
4. Hipp, J. B., Richards, J. J., Wagner, N. J.^* (2019). Structure-property relationships of sheared carbon black suspensions determined by simultaneous rheological and neutron scattering measurements. Journal of Rheology, 63(3), 423–436. https://doi.org/10.1122/1.5071470
5. Hipp, J. B., Richards, J. J., Wagner, N. J.^* (2021). Direct measurements of the microstructural origin of shear-thinning in carbon black suspensions. Journal of Rheology, 65(2), 145. https://doi.org/10.1122/8.0000089
6. Lin, H., Majji, M., Cho, N., Zeeman, J. R. ^†, Swann, J., Richards, J. J. (2022). Quantifying the hydrodynamic contribution to electrical transport in non-Brownian suspensions. Proceedings of the National Academy of Sciences, 119(29)e2203470119. https://doi.org/10.1073/pnas.2203470119
7. Hipp, J. B., Ramos, P. Z., Liu, Q., Wagner, N.J., Richards, J. J. (2024). Quantifying electron transport in aggregated colloidal suspensions in the strong flow regime. Proceedings of the National Academy of Sciences. 121 (34) e2403000121 https://doi.org/10.1073/pnas.2403000121 .
8. Brucks, M. D., Arslanova, A., Smith, C.B.^†, Richards, J. J. (2023). Electroless Deposition of Silver onto Silica Nanoparticles to Produce Lipophilic Core-Shell Nanoparticles. Journal of Colloid and Interface Science 646, 663-670. https://doi.org/10.1016/j.jcis.2023.05.059
9. Brucks, M. D., Arslanova, A., Byrne, N. F.^†, Hui, J., Hersam, M.C., Richards, J. J. (2025) Anisotropic electrical transport in mechanically responsive gels containing silver-coated non-Brownian particles. Advanced Materials. Accepted https://doi/org/10.1002/adma.202415066 .
10. Liu, Q., Richards, J. J. (2023). Rheo-electric measurements of carbon black suspensions containing polyvinylidene difluoride in N-methyl-2-pyrrolidone. Journal of Rheology, 67(3), 647–659. https://doi.org/10.1122/8.0000615
11. Invited Article in September 2024 edition: Richards, J. J., Hipp, J.B. (2024). The black powder behind battery power, Physics Today, 77 (9), 26–32 https://doi.org/10.1063/pt.ercw.haga .
12. Gupta, Y., Liu, Q., Richards, J. J. (2025) Physical Scaling for Predicting Shear Viscosity and Memory Effects of Lithium-Ion Battery Cathode Slurries Soft Matter, Accepted https://doi.org/10.1039/D4SM01493F featured in the Soft Matter Emerging Investigators Series
13. Lin, H., Blackwell, B. C., Call, C. C. ^†, Liu, S., Liu, C., Driscoll, M. M., Richards, J. J. (2023). FSVPy: A python-based package for fluorescent streak velocimetry (FSV). Journal of Rheology, 67(1), 197–206. https://doi.org/10.1122/8.0000521
14. Cho, N., Shi, J., Murphy, R., Riley, J. K., Rogers, S., Richards, J. J. (2023). Extracting Microscopic Insight from Transient Dielectric Measurements made during Large Amplitude Oscillatory Shear on Inverse Worm-like Micelles. Soft Matter, 19 (48), 9379-9388. https://doi.org/10.1039/D3SM00786C
15. Patel, K. J., Bowles, S., Matolyak, L. E., Vogus, D., Wang, C., Nagy, G., Richards, J. J. (2024) Mapping structure and rheology of pH-responsive resins for low-VOC coatings. ACS Applied Materials & Interfaces 16 (51) 70874-70882 https://doi.org/10.1021/acsami.4c15652 .