Water Tales in Nanoscale Environments

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• Dr Damian Scherlis, University of Buenos Aires
• Wednesday 04 December 2024, 14:30-15:30
• Unilever Lecture Theatre, Yusuf Hamied Department of Chemistry.

If you have a question about this talk, please contact Lisa Masters.

Nanoscale confinement alters practically every physical chemical property of water that has been experimentally probed. In pores of 2 or 3 nm the melting temperature is shifted down by more than 50 C, whereas the dielectric constant was reported to drop by an order of magnitude. Understanding the physics and chemistry of water at the nanoscale is critical to explain—and control—its behavior in porous materials, atmospheric aerosols, membranes or protein pockets, while posing at the same time fundamental physical questions. The most usual theoretical framework to deal with confined water is classical thermodynamics. The Young-Laplace or the Kelvin equations, or Henry’s law, are commonly applied to describe the equilibrium properties of water in nanospaces. This is often done with a justified skepticism and without a clear knowledge of the actual limits of these relations to capture the nature of water in nanoscopic regimes. Throughout this talk, I will review some of our findings emerging from molecular simulations, including the liquid-gas equilibrium and bubble nucleation in nanoelectrodes, consistently showing that macroscopic thermodynamics can be safely applied to describe the behavior of water down to unexpectedly small spatial lengths, when the dimensions of the nanophase become comparable to the molecular size. Our results suggest that thermodynamics preserves its predictive power as far as the underlying hypothesis, namely well defined interfaces and homogeneous densities, be fulfilled in a dynamical sense, through the temporal averaging of the molecular motion. This establishes a peculiar connection between thermodynamics and time.

References:

[1] PNAS 2024 121 , e2406956121 [2] Nano Lett. 2023 23, 7206 [3] Angew. Chem. 2023, 62, e202306526 [4] J. Phys. Chem. Lett. 2020 11, 6573 [5] J. Am. Chem. Soc. 2014 136, 4508

This talk is part of the Theory - Chemistry Research Interest Group series.

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