(7ch) Colloidal Fluids As Electrical Current Collectors

Authors: 
Richards, J. J. - Presenter, National Institute of Standards and Technology
Research Interests: Advances in synthetic techniques have enabled a revolution in the design of colloidal dispersions containing particles with a great diversity of sizes, shapes and compositions. This has provided not only for a sophisticated understanding of the intimate link between a dispersion’s microstructure and its macroscopic properties, but also the basis for a powerful design paradigm for the development of new materials to address a wide range of engineering problems. To realize this future, there remain significant scientific challenges both in terms of formulation science and the continued development of a detailed understanding of the relationships between a dispersion’s microstructure and its macroscopic behavior. In situ measurements of colloidal microstructure are an increasingly important component to inform this goal as they provide information both about the quiescent properties of colloidal dispersions but also their properties under simple shear where time-dependent structural evolution proves important to understand their behavior.

Current Research: I will highlight the progress I have made toward understanding the relationship between the electrical conductivity and the rheological properties of suspensions of electrically conductive nanoparticles in the quiescent state and under steady shear. Such suspensions find use as the conducting current collectors in electrochemical flow applications. Key to their performance in this application is a trade-off that arises between maximizing electrical conductivity and minimizing viscosity. To study the origin of this trade-off, suspensions of high structured carbon blacks are formulated in neat propylene carbonate and are characterized, using small amplitude oscillatory shear and impedance spectroscopy, to elucidate their electrorheological behavior spanning their fluid-gel transition. Using these methods, I identify the electrical and mechanical percolation transitions and couple these measurements with small angle neutron scattering experiments to probe their microstructural origin. The comprehensive picture provided by the combination of these three measurements harmonizes several emerging experimental results and guides the development of current collectors with improved performance. Future directions for this research involve looking at the field dependence mobility of electrons through suspensions of conducting particles and its link to particle dynamics.

Education:

2015-Present NRC Postdoctoral Researcher – National Institute of Standards and Technology – NCNR Advisor: Paul D. Butler and Norman J. Wagner

2009-2014 Doctor of Philosophy - University of Washington - “Structural Characterization of Composite Thin-Film and Dispersed Phase Conjugated Polymer/Fullerene Composites”: Advisor: Lilo D. Pozzo

Teaching Interests: I know that the success of my career as a professor in chemical engineering will be evaluated not only by my research but also based on my efficacy as an instructor, a mentor, and a research advisor. True mastery of each of these roles is a lifetime endeavor, but I have developed a strong foundation on which to build a successful teaching career. The training I received as I acquired my B.S. and PhD in chemical engineering as well as my research interests has natural connections with undergraduate Heat and Mass Transport and Thermodynamics coursework. I also have extensive experience in instructing students in the field of colloids and interfacial sciences both at the undergraduate and graduate level and materials characterization.