Do interfacial material properties exist (and what do we really measure there)?
Abstract:
Interfaces obviously cannot exist without the adjacent bulk phases. How, then, can we possibly believe that they possess independent properties? More concretely, say for a liquid coexisting with its vapor, we can ask the following questions: Can the temperature of an interface be different from the temperatures of the adjacent bulk phases, even if they are only a nanometer apart? Can the interface possess a viscosity that is independent of the properties of the surrounding bulk fluids? Conceptual clarifications are of obvious importance for guiding both experiments and modeling efforts for interfaces. I will address this kind of questions on the basis of equilibrium and nonequilibrium thermodynamics [1]. On our way we’ll find out what happened to the degrees of freedom lost according to the “Gibbs Phase Rule” due to phase coexistence. In the last part of my presentation I would like to speculate how interfacial statistical mechanics could look like, both for static and for dynamic properties [2].
[1] See Chapters 13-15 of D. C. Venerus and H. C. Öttinger, A Modern Course in Transport Phenomena (Cambridge University Press, Cambridge, 2018).
[2] A. Montefusco, M. A. Peletier and H. C. Öttinger, Coarse-graining via the fluctuation-dissipation theorem and large-deviation theory (https://arxiv.org/abs/1809.07253).
Biography
Professor Hans Christian Ottinger is interested in nonequilibrium systems and the behaviour of complex fluids or soft matter. He studied physics at the University of Freiburg in Germany, and completed his postdoctoral research at the Chemical Engineering Department and Rheology Research Center at the University of Wisconsin. He has been a Professor of Polymer Physics in the Department of Materials at ETH Zurich since 1996. In 2008 he received the Bingham Medial for outstanding contributions to the field of rheology. He became a Fellow of the Society of Rheology in 2015 and a Member of the Swiss Academy of Engineering Sciences in 2017.