Simon Rogers

Simon Rogers

2022 Metzner Awardee

University of Illinois at Urbana-Champaign

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For developing fundamentally new experimental and analytical methods for linear and nonlinear transient rheology that have provided an improved understanding of complex flow phenomena in yield stress fluids, polymer solutions, and colloidal suspensions.

Simon Rogers, Assistant Professor of Chemical and Biomolecular Engineering at the University of Illinois at Urbana-Champaign, is the recipient of the 2022 Arthur B. Metzner Early Career Award from The Society of Rheology. Simon’s research focuses on understanding the structure and dynamics of soft materials far-from-equilibrium by developing creative new experimental and analytical modeling techniques. In recent years, Simon’s work has provided an improved understanding of complex flow phenomena in yield stress fluids, polymer solutions, and colloidal suspensions by developing fundamentally new experimental and analytical methods for linear and nonlinear transient rheology.

Simon Rogers obtained his Ph.D. in Physics from Victoria University of Wellington in New Zealand in 2011 under the supervision of the late Sir Paul Callaghan. During his Ph.D., Simon used rheo-nuclear magnetic resonance (rheo-NMR) and rheological methods to study the aging and rejuvenation of soft glassy materials. It was during that time that he developed a keen interest in transient nonlinear rheology. Following the completion of his Ph.D., Simon became a postdoctoral research associate at the Foundation for Research and Technology - Hellas (FORTH) in Crete, Greece, where he worked with Dimitris Vlassopoulos on the rheology of ring and star polymers. Simon then moved to the Forschungszentrum Jülich, where he worked with Peter Lang, in the group of Jan Dhont, on understanding the nearwall dynamics of colloids using evanescent wave dynamic light scattering. In October 2012, Simon moved across the Atlantic to the University of Delaware, where he worked with Norm Wagner and served as the UD liaison to the National Institute of Standards and Technology’s Center for Neutron Research. During his time at Delaware, Simon also interacted with Antony Beris, where he developed an interest in experimental and theoretical descriptions of thixotropy. In August 2015, Simon began his position as Assistant Professor in the Department of Chemical and Biomolecular Engineering at the University of Illinois at Urbana-Champaign.

Not surprisingly, Simon has been honored by multiple awards and accolades in his career. Simon was awarded the NSF CAREER award in 2019, a Doctoral New Investigator Award from the American Chemical Society Petroleum Research Fund (ACS PRF) in 2018, and the School of Chemical Sciences Teaching Award at the University of Illinois at Urbana-Champaign in 2020. He was recently awarded the 2022 Campus Distinguished Promotion Award at Illinois and has been named a 2022-2023 I. C. Gunsalus Scholar. He has given over 30 invited lectures at national and international conferences and universities.

A main focus of Simon’s independent research program lies in combining bulk rheological characterization of materials with dynamic, molecular-level structure determination using scattering. In this area of research, Simon’s work addresses long-standing challenges in understanding the far-from-equilibrium behavior of soft materials by directly linking microstructural rearrangements to macroscopic flow properties. In one demonstration, his group showed that bulk stress can be unambiguously understood from local microstructural rearrangements in wormlike micelles and polymer networks using time-resolved rheo-small-angle neutron scattering (rheo-SANS) (Lee et al. Phys. Rev. Lett., 2019). Impressively, this work showed that nonlinear rheological structure-property relations can be clearly determined using a new analytical framework developed by Simon and his team known as ‘transient recovery rheology’. Broadly, this framework relies on performing traditional strain-controlled and stress-controlled rheological experiments with zero-stress imposed recovery steps during the experiment. Using this approach, his group is able to clearly quantify and track the evolution of the recoverable component of the strain during a deformation experiment. Remarkably, Simon and his team found that the recoverable strain correlates with the temporal evolution of microstructure, which revealed that the shear stress and normal stress evolution in materials such as polymer networks and wormlike micelles is controlled by the recoverable strain. This groundbreaking work provides a fundamentally new framework with which to perform and analyze nonlinear rheological experiments that differs from the traditional measure of ‘shear strain’ in a sample, which invariably consists of components of strain that can be recovered (elastic strain) and components that are unrecoverable during a deformation event.

Using the transient recovery rheology framework, Simon and his team have also provided a new way to understand transient oscillatory rheology experiments such as large amplitude oscillatory shear (LAOS). When viewed in the context of recoverable strain, stress-recoverable strain curves show clear, physically relevant features, such as a linear relation between stress and strain for intermediate ranges of recoverable strain. Within the framework of recovery rheology, the transient Lissajous curves begin to make physical sense (e.g., linear relations are obtained between stress and recoverable strain, which reveals a plateau modulus), as opposed to viewing them in the traditional units of shear strain, where a physical interpretation of elliptical curves in stress-shear strain axes can be elusive. Simon’s advances in this area hold important implications for designing new rheological protocols and definitions of important dimensionless groups such as the Deborah number (Rogers et al., Rheol. Acta, 2019), for developing new property-processing relationships for soft materials (Donley et al., Proc. Nat. Acad. Sciences, 2020; Singh et al., Journal of Rheology, 2020), and in the development of new models for yield stress fluids (Kamani et al., Phys. Rev. Lett., 2021). Moreover, this approach has provided a new understanding of the Payne effect in filled polymers and the G” overshoot in concentrated suspensions and yield stress fluids.

Simon has also developed a new framework for understanding large amplitude oscillatory shear (LAOS) known as the ‘sequence of physical processes’ (SPP). Importantly, the SPP framework has provided an unambiguous and systematic framework for understanding transient, non-linear materials deformation protocols by considering the dynamics as a sequence of processes occurring within the material described by differential geometry and the Frenet-Serret apparatus. Simon’s work in this area has had a significant impact on the field, with broad adoption of open-access SPP software by over 35 companies, collaborators, and national labs. In one demonstration of the SPP method, Simon and his team studied the transient structural and rheological behavior of soft glassy materials far-from-equilibrium under small, medium, and large amplitude oscillatory shear (Park and Rogers, Journal of Rheology, 2018). Through such publications, it was shown that the SPP modulus reflects how much of the imposed strain is stored in the form of recoverable elastic strain, establishing it as an accurate measure of structural elasticity. The SPP method was further validated by directly matching strain values estimated solely on the basis of the macroscopic stress to structural measures. In 2018, Simon provided a clear overview of the LAOS analysis literature and the SPP method in a featureinvited article in Physics Today.

Simon is an active member and contributor of The Society of Rheology. Professor Rogers continues to serve on the Membership Committee for The Society of Rheology and as one of two SoR Representatives on the AIPP Publishing Partners Committee, and he participated in the first Rheology Research Symposium in 2019. Simon is serving as the local arrangements chair for the 2022 Annual Meeting of The Society of Rheology in Chicago.

Simon’s creative work continues to push the boundaries of modern rheology into new and interesting directions. Simon is outgoing and engaging, and he brings a warm and welcoming spirit to personal and scientific conversations and meetings. Simon continues to draw in new members into our Society, and he is an outstanding citizen for the rheology community. We look forward to seeing the ongoing contributions that Simon will bring to the field of rheology and the ways in which he will continue to inspire researchers in our Society at all levels of their careers in the future.