Simulations of Nanoseparated Charged Surfaces Reveal Charge-Induced Water Reorientation and Nonadditivity of Hydration and Mean-Field Electrostatic Repulsion
Publikationstyp
Journal Article
Date Issued
2019-01-15
Sprache
English
Author(s)
Journal
Volume
35
Issue
2
Start Page
551
End Page
560
Citation
Langmuir 35 (2): 551-560 (2019)
Publisher DOI
Scopus ID
Publisher
American Chemical Society (ACS)
We perform atomistic simulations of nanometer-separated charged surfaces in the presence of monovalent counterions at fixed water chemical potential. The counterion density profiles are well described by a modified Poisson-Boltzmann (MPB) approach that accounts for nonelectrostatic ion-surface interactions, while the effects of smeared-out surface-charge distributions and dielectric profiles are found to be relatively unimportant. The simulated surface interactions are for weakly charged surfaces well described by the additive contributions of hydration and MPB repulsions, but already for a moderate surface charge density of σ = -0.77 e/nm 2 this additivity breaks down. This we rationalize by a combination of different effects, namely, counterion correlations as well as the surface charge-induced reorientation of hydration water, which modifies the effective water dielectric constant as well as the hydration repulsion. ©
DDC Class
620: Engineering