Title: Impact of Dispersion Solvent on Ionomer Thin Films and Membranes

Abstract

Perfluorosulfonic acid (PFSA) ionomers are an important class of materials that many electrochemical devices rely on as their ion-conducting electrolyte. Often, PFSA films are prepared through solution-processing techniques. Previous research has demonstrated that the solvent environment affects PFSA dispersion conformation, but it is not clear to what extent (if at all) these conformational effects persist for thin films and membranes upon casting, nor how dispersion solvent impacts film formation during the drying process. Here, we explore these questions by systematically examining the effect of water and n-propanol mixtures on PFSA thin-film formation and structure, membrane structure, and resulting properties. Using a combination of in situ, time-resolved grazing incidence X-ray scattering and tender wide-angle X-ray scattering, it is shown that films prepared from high-water-concentration dispersions exhibit stronger interactions and arrangement upon drying, and possess larger network domain sizes than those prepared from low-water-concentration dispersions. These stronger interactions likely manifest in greater network connectivity, as evidenced by enhanced conductivity for membranes and decreased water uptake for thin films. Significantly, these solvent-induced differences persist even after thermal annealing. It is clear that the dispersion solvent choice is a critical parameter controlling PFSA nano- and mesoscale structure and presents an important dial with whichmore » to direct PFSA macroscale properties.« less

Authors:

Berlinger, Sarah A.  ^[1];

• Search DOE PAGES for author "Berlinger, Sarah A."
• Search DOE PAGES for ORCID "0000-0002-0544-6963"

Dudenas, Peter J.  ^[1];

• Search DOE PAGES for author "Dudenas, Peter J."
• Search DOE PAGES for ORCID "0000-0002-4578-4182"

Bird, Ashley ^[1]; Chen, Xunkai ^[1]; Freychet, Guillaume ^[2]; McCloskey, Bryan D.  ^[3];

• Search DOE PAGES for author "McCloskey, Bryan D."
• Search DOE PAGES for ORCID "0000-0001-6599-2336"

Kusoglu, Ahmet  ^[4];

• Search DOE PAGES for author "Kusoglu, Ahmet"
• Search DOE PAGES for ORCID "0000-0002-2761-1050"

Weber, Adam Z.  ^[4]

• Search DOE PAGES for author "Weber, Adam Z."
• Search DOE PAGES for ORCID "0000-0002-7749-1624"

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+ Show Author Affiliations

1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
2. Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)
3. Univ. of California, Berkeley, CA (United States)
4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Publication Date:

Mon Nov 23 00:00:00 EST 2020

Research Org.:

Brookhaven National Lab. (BNL), Upton, NY (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Transportation Office. Fuel Cell Technologies Office; National Science Foundation (NSF)

OSTI Identifier:

1762751

Alternate Identifier(s):

OSTI ID: 1869284

Report Number(s):

BNL-220798-2021-JAAM
Journal ID: ISSN 2637-6105

Grant/Contract Number:  

SC0012704; AC02-05CH1123; AC02-0SCH11231; DGE 1752814; AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

ACS Applied Polymer Materials

Additional Journal Information:

Journal Volume: 2; Journal Issue: 12; Journal ID: ISSN 2637-6105

Publisher:

ACS Publications

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; perfluorosulfonic acid; ionomer; solvent; thin film; membrane; dispersion; fuel cells; x-ray scattering