Rectified and Salt Concentration Dependent Wetting of Hydrophobic Nanopores
Name
polster-et-al-2022-rectified-and-salt-concentration-dependent-wetting-of-hydrophobic-nanopores.pdf
Description
Published version
Size
4.92 MB
Format
Adobe PDF
Checksum (MD5)
20165f08b54aeff0f58877d1c401ac90
Author(s)
Polster, Jake W
Aydin, Fikret
de Souza, J Pedro
Bazant, Martin Z
Pham, Tuan Anh
Siwy, Zuzanna S
Date Issued
July 6, 2022
Journal
Journal of the American Chemical Society
Publisher
American Chemical Society
Citation
Polster, Jake W, Aydin, Fikret, de Souza, J Pedro, Bazant, Martin Z, Pham, Tuan Anh et al. 2022. "Rectified and Salt Concentration Dependent Wetting of Hydrophobic Nanopores." Journal of the American Chemical Society, 144 (26).
Version
Final published version
Abstract
Nanopores lined with hydrophobic groups function as switches for water and all dissolved species, such that transport is allowed only when applying a sufficiently high transmembrane pressure difference or voltage. Here we show a hydrophobic nanopore system whose wetting and ability to transport water and ions is rectified and can be controlled with salt concentration. The nanopore we study contains a junction between a hydrophobic zone and a positively charged hydrophilic zone. The nanopore is closed for transport at low salt concentrations and exhibits finite current only when the concentration reaches a threshold value that is dependent on the pore opening diameter, voltage polarity and magnitude, and type of electrolyte. The smallest nanopore studied here had a 4 nm diameter and did not open for transport in any concentration of KCl or KI examined. A 12 nm nanopore was closed for all KCl solutions but conducted current in KI at concentrations above 100 mM for negative voltages and opened for both voltage polarities at 500 mM KI. Nanopores with a hydrophobic/hydrophilic junction can thus function as diodes, such that one can identify a range of salt concentrations where the pores transport water and ions for only one voltage polarity. Molecular dynamics simulations together with continuum models provided a multiscale explanation of the observed phenomena and linked the salt concentration dependence of wetting with an electrowetting model. Results presented are crucial for designing next-generation chemical and ionic separation devices as well as understanding fundamental properties of hydrophobic interfaces under nanoconfinement.
MIT Department
Massachusetts Institute of Technology. Department of Chemical Engineering
Massachusetts Institute of Technology. Department of Mathematics
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DOI of Published Version
https://doi.org/10.1021/jacs.2c03436
