Effect of Surface Alignment on Connectivity in Phosphonium-Containing Diblock Copolymer Anion-Exchange Membranes

Barnes, Austin M.; Du, Yifeng; Liu, Brendan; Zhang, Wenxu; Seifert, Soenke; Coughlin, E. Bryan; Burratto, Steven K.

doi:10.1021/acs.jpcc.9b08626

Title: Effect of Surface Alignment on Connectivity in Phosphonium-Containing Diblock Copolymer Anion-Exchange Membranes

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Abstract

The performance of ion-exchange membranes in fuel cells is critically linked to their ion-conducting morphology. In this report, we analyzed the connectivity of anion-exchange membranes (AEMs) by electrostatic force microscopy (EFM). As a tapping-mode AFM-based technique, EFM probes height, phase, and electrostatic force gradient through two-pass interleave scans, which reveals the direct relationship between membrane surface morphology and connectivity of the ionic domain. The AEMs are diblock copolymers of a polyisoprene (PIp) block and a polystyrenic block containing the phosphonium ion (P(R3P+)MS). Different alignments of cylinders were observed in the bulk and on the surface for AEMs with different ionexchange capacities (IECs) and preparation methods. The impacts of the cylinder alignment on the connectivity of the ionic domain were then investigated by EFM. For AEM 13 with IEC = 0.44 mmol/g and a hexagonal morphology, cylinders aligned parallel to the surface, which led to many disconnected regions observed throughout the membrane. In contrast, the perpendicularly aligned channels of AEM 16 with IEC = 0.87 mmol/g consisted only of a well-connected ionic phase throughout the membrane.

Authors:

Barnes, Austin M. ^[1]; Du, Yifeng ^[2]; Liu, Brendan ^[1]; Zhang, Wenxu ^[2]; Seifert, Soenke ^[3]; Coughlin, E. Bryan ^[2]; Burratto, Steven K. ^[1]

Univ. of California, Santa Barbara, CA (United States)
Univ. of Massachusetts, Amherst, MA (United States)
Argonne National Lab. (ANL), Argonne, IL (United States)

Publication Date:: Sun Nov 24 00:00:00 EST 2019

Research Org.:: Argonne National Lab. (ANL), Argonne, IL (United States)

Sponsoring Org.:: U.S. Army Research Laboratory - U.S. Army Research Office (ARO); National Science Foundation (NSF); USDOE

OSTI Identifier:: 1630702

Grant/Contract Number:: AC02-06CH11357

Resource Type:: Accepted Manuscript

Journal Name:: Journal of Physical Chemistry. C

Additional Journal Information:: Journal Volume: 123; Journal Issue: 51

Publisher:: American Chemical Society

Country of Publication:: United States

Language:: English

Subject:: 25 ENERGY STORAGE

Citation Formats


                    Barnes, Austin M., Du, Yifeng, Liu, Brendan, Zhang, Wenxu, Seifert, Soenke, Coughlin, E. Bryan, and Burratto, Steven K. Effect of Surface Alignment on Connectivity in Phosphonium-Containing Diblock Copolymer Anion-Exchange Membranes.  United States: N. p., 2019. 
Web.  doi:10.1021/acs.jpcc.9b08626.

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                    Barnes, Austin M., Du, Yifeng, Liu, Brendan, Zhang, Wenxu, Seifert, Soenke, Coughlin, E. Bryan, & Burratto, Steven K. Effect of Surface Alignment on Connectivity in Phosphonium-Containing Diblock Copolymer Anion-Exchange Membranes.  United States.  https://doi.org/10.1021/acs.jpcc.9b08626

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                    Barnes, Austin M., Du, Yifeng, Liu, Brendan, Zhang, Wenxu, Seifert, Soenke, Coughlin, E. Bryan, and Burratto, Steven K. Sun .  
"Effect of Surface Alignment on Connectivity in Phosphonium-Containing Diblock Copolymer Anion-Exchange Membranes".  United States.  https://doi.org/10.1021/acs.jpcc.9b08626.  https://www.osti.gov/servlets/purl/1630702.

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@article{osti_1630702,

  title        = {Effect of Surface Alignment on Connectivity in Phosphonium-Containing Diblock Copolymer Anion-Exchange Membranes},

  author       = {Barnes, Austin M. and Du, Yifeng and Liu, Brendan and Zhang, Wenxu and Seifert, Soenke and Coughlin, E. Bryan and Burratto, Steven K.},

  abstractNote = {The performance of ion-exchange membranes in fuel cells is critically linked to their ion-conducting morphology. In this report, we analyzed the connectivity of anion-exchange membranes (AEMs) by electrostatic force microscopy (EFM). As a tapping-mode AFM-based technique, EFM probes height, phase, and electrostatic force gradient through two-pass interleave scans, which reveals the direct relationship between membrane surface morphology and connectivity of the ionic domain. The AEMs are diblock copolymers of a polyisoprene (PIp) block and a polystyrenic block containing the phosphonium ion (P(R3P+)MS). Different alignments of cylinders were observed in the bulk and on the surface for AEMs with different ionexchange capacities (IECs) and preparation methods. The impacts of the cylinder alignment on the connectivity of the ionic domain were then investigated by EFM. For AEM 13 with IEC = 0.44 mmol/g and a hexagonal morphology, cylinders aligned parallel to the surface, which led to many disconnected regions observed throughout the membrane. In contrast, the perpendicularly aligned channels of AEM 16 with IEC = 0.87 mmol/g consisted only of a well-connected ionic phase throughout the membrane.},

  doi          = {10.1021/acs.jpcc.9b08626},

  journal      = {Journal of Physical Chemistry. C},

  number       = 51,

  volume       = 123,

  place        = {United States},

  year         = {Sun Nov 24 00:00:00 EST 2019},

  month        = {Sun Nov 24 00:00:00 EST 2019}

}

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