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Title: Polyimide-PEG Segmented Block Copolymer Membranes with High Proton Conductivity by Improving Bicontinuous Nanostructure of Ionic Liquid-Doped Films

Abstract

The structure and properties of segmented block copolymer films of aromatic polyimide (PI) and poly(ethylene glycol) (PEG) doped with an ionic liquid are observed for potential polymer electrolyte membrane applications for fuel cells. Poly(amic acid) precursors of PI-PEG copolymers of 4,4'-(hexafluoroisopropylidene) diphthalic anhydride, 4,4'-(1,3-phenylenedioxy) dianiline, and bis(3-aminopropyl) terminated PEG (M n ≈ 1500) are synthesized and then thermally imidized in membrane films, followed by swelling in ethylammonium nitrate (EAN) ionic liquid. The small-angle X-ray scattering results from the EAN-doped PI-PEG copolymer films show disordered bicontinuous phase-separated nanostructures described by Teubner–Strey theory, with the interface fractal dimension determined from the Porod equation. Thermal annealing of the EAN-doped membranes at 100–140 °C results in increased correlation lengths and smoother interfaces of the bicontinuous nanostructures. Such improved nanostructures lead to the increased ionic conductivity by two to five times with the maximum conductivity of 210 mS cm -1 at 60 °C and 70% RH, much greater (nearly fivefold) than that of Nafion films, while maintaining the mechanical stability possibly up to 140 °C. Furthermore, the investigation of the disordered bicontinuous phase-separated nanostructure of EAN-doped PI-PEG copolymer membranes is highly relevant to understanding the nanostructures of hydrated Nafion membranes and segmented block copolymers inmore » general.« less

Authors:
 [1];  [2];  [2];  [2];  [3]; ORCiD logo [2];  [2]
  1. Stanford Univ., CA (United States); Lotte Advanced Materials Co., Ltd., Uiwang‐si (Republic of Korea)
  2. Stanford Univ., CA (United States)
  3. SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
OSTI Identifier:
1532506
Grant/Contract Number:  
AC02-76SF00515; 1511373
Resource Type:
Accepted Manuscript
Journal Name:
Macromolecular Chemistry and Physics
Additional Journal Information:
Journal Volume: 220; Journal Issue: 9; Journal ID: ISSN 1022-1352
Publisher:
Wiley
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; bicontinuous structures; ionic liquids; polymer electrolyte membranes; segmented block copolymers

Citation Formats

Woo, Euntaek, Coletta, Elyse, Holm, Alexander, Mun, Jaewan, Toney, Michael F., Yoon, Do Y., and Frank, Curtis W. Polyimide-PEG Segmented Block Copolymer Membranes with High Proton Conductivity by Improving Bicontinuous Nanostructure of Ionic Liquid-Doped Films. United States: N. p., 2019. Web. doi:10.1002/macp.201900006.
Woo, Euntaek, Coletta, Elyse, Holm, Alexander, Mun, Jaewan, Toney, Michael F., Yoon, Do Y., & Frank, Curtis W. Polyimide-PEG Segmented Block Copolymer Membranes with High Proton Conductivity by Improving Bicontinuous Nanostructure of Ionic Liquid-Doped Films. United States. doi:10.1002/macp.201900006.
Woo, Euntaek, Coletta, Elyse, Holm, Alexander, Mun, Jaewan, Toney, Michael F., Yoon, Do Y., and Frank, Curtis W. Wed . "Polyimide-PEG Segmented Block Copolymer Membranes with High Proton Conductivity by Improving Bicontinuous Nanostructure of Ionic Liquid-Doped Films". United States. doi:10.1002/macp.201900006.
@article{osti_1532506,
title = {Polyimide-PEG Segmented Block Copolymer Membranes with High Proton Conductivity by Improving Bicontinuous Nanostructure of Ionic Liquid-Doped Films},
author = {Woo, Euntaek and Coletta, Elyse and Holm, Alexander and Mun, Jaewan and Toney, Michael F. and Yoon, Do Y. and Frank, Curtis W.},
abstractNote = {The structure and properties of segmented block copolymer films of aromatic polyimide (PI) and poly(ethylene glycol) (PEG) doped with an ionic liquid are observed for potential polymer electrolyte membrane applications for fuel cells. Poly(amic acid) precursors of PI-PEG copolymers of 4,4'-(hexafluoroisopropylidene) diphthalic anhydride, 4,4'-(1,3-phenylenedioxy) dianiline, and bis(3-aminopropyl) terminated PEG (Mn ≈ 1500) are synthesized and then thermally imidized in membrane films, followed by swelling in ethylammonium nitrate (EAN) ionic liquid. The small-angle X-ray scattering results from the EAN-doped PI-PEG copolymer films show disordered bicontinuous phase-separated nanostructures described by Teubner–Strey theory, with the interface fractal dimension determined from the Porod equation. Thermal annealing of the EAN-doped membranes at 100–140 °C results in increased correlation lengths and smoother interfaces of the bicontinuous nanostructures. Such improved nanostructures lead to the increased ionic conductivity by two to five times with the maximum conductivity of 210 mS cm-1 at 60 °C and 70% RH, much greater (nearly fivefold) than that of Nafion films, while maintaining the mechanical stability possibly up to 140 °C. Furthermore, the investigation of the disordered bicontinuous phase-separated nanostructure of EAN-doped PI-PEG copolymer membranes is highly relevant to understanding the nanostructures of hydrated Nafion membranes and segmented block copolymers in general.},
doi = {10.1002/macp.201900006},
journal = {Macromolecular Chemistry and Physics},
number = 9,
volume = 220,
place = {United States},
year = {2019},
month = {4}
}

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Works referenced in this record:

Polymer-Polymer Phase Behavior
journal, February 1991


Morphology of Hydrated As-Cast Nafion Revealed through Cryo Electron Tomography
journal, December 2014

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