They Call It “Free Energy” So, Hey, Why Pay?

Abstract: The emergence of order in materials systems ranging from simple salts to complex supramolecular arrays has long been viewed through the lens of classical nucleation theory in which monomeric building blocks assemble into ordered structures through inherent thermal fluctuations that overcome a free energy barrier. However, recent observations have revealed a rich set of hierarchical pathways involving higher-order species ranging from multi-ion clusters to dense liquid droplets to transient amorphous or crystalline phases. Macromolecular systems exhibit particularly rich assembly dynamics due to their conformational flexibility and interactions that span many length scales. Despite the complexity of these pathways, a holistic framework for understanding them based on classical concepts emerges when one considers perturbations in the free energy landscape from a smoothly varying surface to one rich in minima and maxima, as well as dynamical factors that drive hierarchical pathways due to kinetic constraints. I illustrate that framework using in situ TEM and AFM studies of inorganic, organic, and macromolecular systems, which provide a molecular-scale view of assembly pathways and dynamics. In particular, the results highlight the key role of interfaces in creating heterogenous distributions of water and ions, which create low barrier pathways to ordering. The findings provide a common basis for understanding the development of order in diverse systems.

Bio: Jim De Yoreo is a Battelle Fellow and Chief Scientist for Materials Science in the Physical and Computational Sciences Directorate at Pacific Northwest National Laboratory (PNNL), an Affiliate Professor of Materials Science and Engineering and of Chemistry at the University of Washington, and Co-Director of the Northwest Institute for Materials Physics, Chemistry and Technology (NW IMPACT).  He received his PhD in Physics from Cornell University in 1985.  Following post-doctoral work at the University of Maine and at Princeton University, he became a member of the technical staff at Lawrence Livermore National Laboratory in 1989, where he held numerous positions. He joined Lawrence Berkeley National Laboratory in 2007 where he served as Deputy and then Interim Director of the Molecular Foundry before moving to PNNL in 2012. De Yoreo’s research has spanned a range of materials-related disciplines, focusing recently on interactions, assembly, and crystallization in inorganic, biomolecular and biomineral systems.  De Yoreo has authored, co-authored, or edited over 250 publications and patents. He is a recipient of the David Turnbull Lectureship of the Materials Research Society (MRS), the Laudise Prize of the International Organization for Crystal Growth (IOCG) and the Crystal Growth Award of the American Association for Crystal Growth (AACG). He served as President of the MRS and he is a Fellow of the American Physical Society and the MRS, and a member of the Washington State Academy of Sciences and the IOCG and AACG Executive Committees.

All seminars are held on Wednesdays from 12:00 noon-1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.