(294d) A Molecular Perspective of Wetting and Charging at Polymer Interfaces

Interactions at water-polymer surfaces underlie many important natural and technological phenomena. In this talk, I will discuss quantitative theoretical approaches—namely molecular-level analyses and free-energy calculations—to understand and quantify the (i) wetting and (ii) contact charging behavior of chemically distinct polymer surfaces. Related to wetting, we will show how hydrogen-bonding behavior and surface morphology dictates and differentiates polymer surfaces, even when macroscopic measures of hydrophobicity fail to resolve any differences. Related to contact charging, which refers to how surfaces become asymmetrically charged following contact and separation, we will evaluate a new, molecularly informed hypothesis that can predict the direction of charge transfer between two surfaces. Although water is thought to play a central role in contact charging of insulating surfaces, like polymers, the mechanism of charging is unknown and hard to isolate via experiment. Whereas many existing hypotheses rely on kinetic arguments, we assess whether thermodynamic driving forces, informed by our free energy calculations, can feasibly explain experimental trends. Overall, this presentation will highlight how molecular simulation can help us to understand complex interfacial phenomena.