Phosphonium-Containing Block Copolymer Anion Exchange Membranes: Effect of Quaternization Level on Bulk and Surface Morphologies at Hydrated and Dehydrated States

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

doi:10.1021/acs.macromol.9b00665

Title: Phosphonium-Containing Block Copolymer Anion Exchange Membranes: Effect of Quaternization Level on Bulk and Surface Morphologies at Hydrated and Dehydrated States

Abstract

Diblock copolymers of isoprene and chloromethylstyrene were synthesized by nitroxide-mediate polymerization. The polychloromethylstyrene block was quaternized with tris(trimethoxyphenyl)phosphine (P(Ph(OMe)₃)₃) or triphenyl-phosphine (P(Ph)₃). Membranes with ion-exchange capacity (IEC) ranging from 0.87 to 2.35 mmol/g were prepared. The bulk morphology was investigated via small-angle X-ray scattering and transmission electron microscopy, where hexagonal and body-centered cubic morphologies were observed. The surface morphology was revealed by atomic force microscopy where both parallel and perpendicular alignments were observed. Compared to P(Ph(OMe)₃)₃, P(Ph)₃ exhibits higher quaternization efficiency due to less steric hindrance. Partially quaternized membranes were prepared using P(Ph)₃, and the dependence of domain size on the quaternization level is discussed. The morphologies as a function of relative humidity were investigated. For high IEC membranes, although bulk scattering showed small changes in d-spacing, large changes in domain size on the surface occurred between hydrated and dehydrated conditions. Finally, further investigations of morphological reversibility by humidity cycling showed good recovery between humid and dry conditions, indicating that the expansion and contraction of channels is a reversible process.

Authors:

Barnes, Austin M. ^[1]; Du, Yifeng ^[2]; Zhang, Wenxu ^[2]; Seifert, Soenke ^[3]; Buratto, Steven K. ^[1];

^[2]

Univ. of California, Santa Barbara, CA (United States). Dept. of Chemistry and Biochemistry
Univ. of Massachusetts, Amherst, MA (United States). Dept. of Polymer Science and Engineering
Argonne National Lab. (ANL), Argonne, IL (United States). X-Ray Science Division

Publication Date:: Tue Aug 06 00:00:00 EDT 2019

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

Sponsoring Org.:: US Army Research Office (ARO); National Science Foundation (NSF); US Army Research Laboratory (USARL)

OSTI Identifier:: 1574824

Grant/Contract Number:: AC02-06CH11357

Resource Type:: Accepted Manuscript

Journal Name:: Macromolecules

Additional Journal Information:: Journal Volume: 52; Journal Issue: 16; Journal ID: ISSN 0024-9297

Publisher:: American Chemical Society

Country of Publication:: United States

Language:: English

Subject:: 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats


                    Barnes, Austin M., Du, Yifeng, Zhang, Wenxu, Seifert, Soenke, Buratto, Steven K., and Coughlin, E. Bryan. Phosphonium-Containing Block Copolymer Anion Exchange Membranes: Effect of Quaternization Level on Bulk and Surface Morphologies at Hydrated and Dehydrated States.  United States: N. p., 2019. 
Web.  doi:10.1021/acs.macromol.9b00665.

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                    Barnes, Austin M., Du, Yifeng, Zhang, Wenxu, Seifert, Soenke, Buratto, Steven K., & Coughlin, E. Bryan. Phosphonium-Containing Block Copolymer Anion Exchange Membranes: Effect of Quaternization Level on Bulk and Surface Morphologies at Hydrated and Dehydrated States.  United States.  https://doi.org/10.1021/acs.macromol.9b00665

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                    Barnes, Austin M., Du, Yifeng, Zhang, Wenxu, Seifert, Soenke, Buratto, Steven K., and Coughlin, E. Bryan. Tue .  
"Phosphonium-Containing Block Copolymer Anion Exchange Membranes: Effect of Quaternization Level on Bulk and Surface Morphologies at Hydrated and Dehydrated States".  United States.  https://doi.org/10.1021/acs.macromol.9b00665.  https://www.osti.gov/servlets/purl/1574824.

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@article{osti_1574824,

  title        = {Phosphonium-Containing Block Copolymer Anion Exchange Membranes: Effect of Quaternization Level on Bulk and Surface Morphologies at Hydrated and Dehydrated States},

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

  abstractNote = {Diblock copolymers of isoprene and chloromethylstyrene were synthesized by nitroxide-mediate polymerization. The polychloromethylstyrene block was quaternized with tris(trimethoxyphenyl)phosphine (P(Ph(OMe)3)3) or triphenyl-phosphine (P(Ph)3). Membranes with ion-exchange capacity (IEC) ranging from 0.87 to 2.35 mmol/g were prepared. The bulk morphology was investigated via small-angle X-ray scattering and transmission electron microscopy, where hexagonal and body-centered cubic morphologies were observed. The surface morphology was revealed by atomic force microscopy where both parallel and perpendicular alignments were observed. Compared to P(Ph(OMe)3)3, P(Ph)3 exhibits higher quaternization efficiency due to less steric hindrance. Partially quaternized membranes were prepared using P(Ph)3, and the dependence of domain size on the quaternization level is discussed. The morphologies as a function of relative humidity were investigated. For high IEC membranes, although bulk scattering showed small changes in d-spacing, large changes in domain size on the surface occurred between hydrated and dehydrated conditions. Finally, further investigations of morphological reversibility by humidity cycling showed good recovery between humid and dry conditions, indicating that the expansion and contraction of channels is a reversible process.},

  doi          = {10.1021/acs.macromol.9b00665},

  journal      = {Macromolecules},

  number       = 16,

  volume       = 52,

  place        = {United States},

  year         = {Tue Aug 06 00:00:00 EDT 2019},

  month        = {Tue Aug 06 00:00:00 EDT 2019}

}

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https://doi.org/10.1021/acs.macromol.9b00665

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Cited by: 13 works

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Scheme 1: Synthesis of PIp- P(R₃P⁺)MS by NMP.

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