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Title: A Comparative Study of Phosphoric Acid-doped m-PBI Membranes

Abstract

Phosphoric acid (PA)-doped m-polybenzimidazole (PBI) membranes used in high temperature fuel cells and hydrogen pumps were prepared by a conventional imbibing process and a sol-gel fabrication process. A comparative study was conducted to investigate the critical properties of PA doping levels, ionic conductivities, mechanical properties, and molecular ordering. This systematic study found that sol-gel PA-doped m-PBI membranes were able to absorb higher acid doping levels and to achieve higher ionic conductivities than conventionally imbibed membranes when treated in an equivalent manner. Even at similar acid loadings, the sol-gel membranes exhibited higher ionic conductivities. Heat treatment of conventionally imbibed membranes with 29wt% solids caused a significant reduction in mechanical properties; conversely, sol-gel membranes exhibited an enhancement in mechanical properties. From X-ray structural studies and atomistic simulations, both conventionally imbibed and sol-gel membranes exhibited d-spacings of 3.5 and 4.6 , which were tentatively attributed to parallel ring stacking and staggered side-to-side packing, respectively, of the imidazole rings in these aromatic hetercyclic polymers. An anisotropic staggered side-to-side chain packing present in the conventional membranes may be root to the reduction in mechanical properties.

Authors:
 [1];  [1];  [1];  [2];  [1];  [1]
  1. ORNL
  2. University of Tennessee (UTK) and Oak Ridge National Laboratory (ORNL)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1122648
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Journal of Polymer Science, Part B: Polymer Physics
Additional Journal Information:
Journal Volume: 52; Journal Issue: 1; Journal ID: ISSN 0887-6266
Country of Publication:
United States
Language:
English
Subject:
phosphoric acid doped polybenzimidazole; proton exchange membranes; fuel cells

Citation Formats

Perry, Kelly A, More, Karren Leslie, Payzant, E Andrew, Meisner, Roberta A, Sumpter, Bobby G, and Benicewicz, Brian. A Comparative Study of Phosphoric Acid-doped m-PBI Membranes. United States: N. p., 2014. Web. doi:10.1002/polb.23403.
Perry, Kelly A, More, Karren Leslie, Payzant, E Andrew, Meisner, Roberta A, Sumpter, Bobby G, & Benicewicz, Brian. A Comparative Study of Phosphoric Acid-doped m-PBI Membranes. United States. https://doi.org/10.1002/polb.23403
Perry, Kelly A, More, Karren Leslie, Payzant, E Andrew, Meisner, Roberta A, Sumpter, Bobby G, and Benicewicz, Brian. 2014. "A Comparative Study of Phosphoric Acid-doped m-PBI Membranes". United States. https://doi.org/10.1002/polb.23403.
@article{osti_1122648,
title = {A Comparative Study of Phosphoric Acid-doped m-PBI Membranes},
author = {Perry, Kelly A and More, Karren Leslie and Payzant, E Andrew and Meisner, Roberta A and Sumpter, Bobby G and Benicewicz, Brian},
abstractNote = {Phosphoric acid (PA)-doped m-polybenzimidazole (PBI) membranes used in high temperature fuel cells and hydrogen pumps were prepared by a conventional imbibing process and a sol-gel fabrication process. A comparative study was conducted to investigate the critical properties of PA doping levels, ionic conductivities, mechanical properties, and molecular ordering. This systematic study found that sol-gel PA-doped m-PBI membranes were able to absorb higher acid doping levels and to achieve higher ionic conductivities than conventionally imbibed membranes when treated in an equivalent manner. Even at similar acid loadings, the sol-gel membranes exhibited higher ionic conductivities. Heat treatment of conventionally imbibed membranes with 29wt% solids caused a significant reduction in mechanical properties; conversely, sol-gel membranes exhibited an enhancement in mechanical properties. From X-ray structural studies and atomistic simulations, both conventionally imbibed and sol-gel membranes exhibited d-spacings of 3.5 and 4.6 , which were tentatively attributed to parallel ring stacking and staggered side-to-side packing, respectively, of the imidazole rings in these aromatic hetercyclic polymers. An anisotropic staggered side-to-side chain packing present in the conventional membranes may be root to the reduction in mechanical properties.},
doi = {10.1002/polb.23403},
url = {https://www.osti.gov/biblio/1122648}, journal = {Journal of Polymer Science, Part B: Polymer Physics},
issn = {0887-6266},
number = 1,
volume = 52,
place = {United States},
year = {Wed Jan 01 00:00:00 EST 2014},
month = {Wed Jan 01 00:00:00 EST 2014}
}