Title: Ion movement in thin Nafion films under an applied electric field

Abstract

In this study, the electromechanical response of Nafion films with and without an ionic liquid (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) ([emim]Tf₂N) additive were characterized under an applied electric field in situ using neutron reflectometry (NR) and voltage modulated atomic force microscopy (VM-AFM). NR showed that pure Nafion films exhibited no response under field strengths of ~0.18 V/μm, while VM-AFM measurements showed a minimal response at higher field strengths (~200 V/μm), which is ascribed to the residual water presence in the films. The addition of ionic liquid resulted in clear electroresponsiveness seen in both NR and VM-AFM. NR results indicated mass migration away from the cathodic interface driven by the [emim]⁺ movement in the direction of the electric field. The lack of ionic liquid accumulation at the electrode interfaces contrasts the bulk electromechanical behavior of similar systems reported in the literature. VM-AFM measurements were able to resolve the relative contributions of the [emim]⁺ cation and Tf₂N^- anion to film deformation by alternating the direction of the applied field and support the [emim]⁺ dominant migration seen in the NR results. Lastly, the findings presented here emphasize the need for the nanoscale analysis of material properties of electroresponsive thin film systems and demonstrate the potential formore » probing electric field effects using in situ techniques.« less

Authors:

Dugger, Jason W.  ^[1];

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Collins, Liam F.  ^[1];

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Welbourn, Rebecca J. L. ^[2]; Skoda, Maximilian W. A. ^[2]; Balke, Nina  ^[1];

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Lokitz, Bradley S.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-1229-6078"
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Browning, James F.  ^[3]

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• Search DOE PAGES for ORCID "0000-0001-8379-259X"
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+ Show Author Affiliations

1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS)
2. Rutherford Appleton Laboratory, Didcot (United Kingdom). ISIS, Science and Technology Facilities Council
3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Neutron Scattering Division

Publication Date:

2018-09-12

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1474639

Alternate Identifier(s):

OSTI ID: 1469726

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

Applied Physics Letters

Additional Journal Information:

Journal Volume: 113; Journal Issue: 11; Journal ID: ISSN 0003-6951

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE