Title: Potential-induced wetting and dewetting in pH-responsive block copolymer membranes for mass transport control

Abstract

Wetting and dewetting behavior in channel-confined hydrophobic volumes is used in biological membranes to effect selective ion/molecular transport. Artificial biomimetic hydrophobic nanopores have been devised utilizing wetting and dewetting, however, tunable mass transport control utilizing multiple transport modes is required for applications such as controllable release/transport, water separation/purification and energy conversion. Here, we investigate the potential-induced wetting and dewetting behavior in a pH-responsive membrane composed of a polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer (BCP) when fabricated as a hierarchically-organized sandwich structure on a nanopore electrode array (NEA), i.e. BCP@NEA. At pH < pK_a(P4VP) (pK_a ~ 4.8), the BCP acts as an anion-exchange membrane due to the hydrophilic, protonated P4VP cylindrical nanodomains, but at pH > pK_a(P4VP), the P4VP domains exhibit charge-neutral, hydrophobic and collapsed structures, blocking mass transport via the hydrophobic membrane. However, when originally prepared in a dewetted condition, mass transport in the BCP membrane may be switched on if sufficiently negative potentials are applied to the BCP@NEA architecture. When the hydrophobic BCP membrane is introduced on top of 2-electrode-embedded nanopore arrays, electrolyte solution in the nanopores is introduced, then isolated, by exploiting the potential-induced wetting and dewetting transitions in the BCP membrane. The potential-induced wetting/dewetting transition and the effect onmore » cyclic voltammetry in the BCP@NEA structures is characterized as a function of the potential, pH and ionic strength. Additionally chronoamperometry and redox cycling experiments are used to further characterize the potential response. The multi-modal mass transport system proposed in this work will be useful for ultrasensitive sensing and single-molecule studies, which require long-time monitoring to explore reaction dynamics as well as molecular heterogeneity in nanoconfined volumes.« less

Authors:

Kwon, Seung-Ryong  ^[1];

• Search DOE PAGES for author "Kwon, Seung-Ryong"
• Search DOE PAGES for ORCID "0000-0002-0890-523X"

Baek, Seol  ^[2];

• Search DOE PAGES for author "Baek, Seol"
• Search DOE PAGES for ORCID "0000-0003-2191-6723"

Bohn, Paul W  ^[2]

• Search DOE PAGES for author "Bohn, Paul W"
• Search DOE PAGES for ORCID "0000-0001-9052-0349"

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+ Show Author Affiliations

1. Gyeongsang National University, Jinju (Korea, Republic of)
2. University of Notre Dame, IN (United States)

Publication Date:

Tue Dec 14 00:00:00 EST 2021

Research Org.:

University of Notre Dame, IN (United States)

Sponsoring Org.:

USDOE Office of Science (SC); National Science Foundation (NSF)

OSTI Identifier:

1978789

Alternate Identifier(s):

OSTI ID: 1835630

Grant/Contract Number:  

FG02-07ER15851; 1904196

Resource Type:

Accepted Manuscript

Journal Name:

Faraday Discussions

Additional Journal Information:

Journal Volume: 233; Journal Issue: 0; Journal ID: ISSN 1359-6640

Publisher:

Royal Society of Chemistry

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY