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Nanochannels as Molecular Check Valves

Abstract

Molecular check valve is a nanomachine that enables the unidirectional molecular transport. In this work, we report a novel molecular check valve fabricated by asymmetric modification of silica nanoporous membrane (SNM) consisting of parallel nanochannels with a diameter of 2 ∼ 3 nm. Asymmetric modification refers to the thermal deposition of hydrophobic polydimethylsiloxane (PDMS) only on one side of SNM to generate hydrophobic nanoorifices. Such an asymmetric nanostructure, designated as PDMS-SNM, could exert synergistically a hydrophobic force by PDMS nanoorifices and an electrostatic one by naked silica nanochannels on the molecules, resulting in an unidirectional molecular transport under specific circumstances. Typically, only positively charged molecules were able to transport across the PDMS-SNM from the PDMS nanoorifice side, while the backward transport from the other side was prohibited. In the former case, positively charged molecules were subject to the electrostatic attraction from naked silica channels, which could exceed the hydrophobic rejection from PDMS nanoorifices to pull the molecule across the PDMS-SNM. However, in the latter case the electrostatic attraction is no longer a driving force to overcome the hydrophobic rejection from PDMS nanoorifices to promote the molecular transport. On the other hand, the PDMS-SNM based molecular check valve can be shut down to prevent any molecular transport from either side of PDMS-SNM under certain conditions, such as high salt concentration and appropriate pH (e.g., pH 3). We believe it could be applied to convert the natural fluctuation energy into directed motion, as well as to prevent backward transport in batteries and fuel cells.

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Publication details

The article was received on 10 Aug 2017, accepted on 12 Nov 2017 and first published on 13 Nov 2017


Article type: Paper
DOI: 10.1039/C7NR05924H
Citation: Nanoscale, 2017, Accepted Manuscript
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    Nanochannels as Molecular Check Valves

    Q. Yang, X. Lin, Y. Wang and B. Su, Nanoscale, 2017, Accepted Manuscript , DOI: 10.1039/C7NR05924H

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