On land and in the atmosphere, a dominant form of water is the capillary-condensed liquid within nanometer-scale pores and defects in organic and inorganic solids. In the biosphere, this liquid state defines the availability of water for chemistry and life in soils and controls the transpiration process in plants; in the atmosphere, it plays a critical role in defining the activity of aerosol particles as nuclei for the formation of clouds. The thermodynamic, dynamic and chemical properties of this highly confined liquid water have remained incompletely understood due to the lack of experimental tools for direct interrogation. In this presentation, we will introduce a set of nanofabricated systems and optical measurement techniques developed in our lab to perform quantitative measurements of these elusive properties. We will proceed to provide several illustrative examples of these measurements: 1) exploiting phase-equilibrium with unsaturated vapors and massive capillary stresses, we will show that the dynamics of liquid water (and other common solvents) in few-nanometer-scale confinement agree, quantitatively, with bulk predictions if account is taken for a mono-molecular layer of immobilized liquid. 2) Working under related conditions, we will present an unprecedented measurement of the solubility of molecular oxygen in liquid water at negative pressures, and show that the solubility in capillary condensed water rises significantly (&gt; 2x) under common atmospheric conditions. 3) Exploiting a micro-nano-fluidic system, we will present the first direct measurements of the state of liquid in metastable equilibrium with ice at supercooled temperatures (the Gibbs-Thomson effect). We will conclude with a brief discussion of implications of these measurements for our understanding of environmental phenomena and of perspectives for technological applications.

From plants to clouds – how nanostructured materials mediate transport and phase behavior of water in the environment

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.