Thermal crosslinking of PBI/sulfonated polysulfone based blend membranes

Dickson Joseph, N. Nambi Krishnan, Dirk Henkensmeier, Jong Hyun Jang, Sun Hee Choi, Hyoung Juhn Kim, Jonghee Han, SukWoo Nam

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Crosslinked polybenzimidazole (PBI) membranes are most often obtained by reacting the nitrogen atoms of PBI with an alkylating agent. These links can be attacked by nucleophiles at elevated temperatures. To avoid N-CH2-links we introduce a new method to crosslink PBI, starting from ionically crosslinked acid/base blend membranes. By heating them to temperatures above say 200 °C, a Friedel-Crafts reaction between sulfonic acid groups and electron rich phenyl groups covalently crosslinks the acid and base components in the blend by chemically stable aromatic sulfone bonds. According to the literature pure PBI can also be cured and a radical mechanism involving air was suggested. We show that PBI can also be cured in an inert atmosphere. We propose that the thermal curing of pure PBI, which necessitates slightly higher temperatures than blend membranes, proceeds via hydrolysis of imidazole to-COOH and diamine, followed by a Friedel-Crafts reaction of the acid. While crosslinks cannot be directly analysed by nmr or IR, our data support the mentioned mechanism. We show the effect of curing temperature and time on membrane properties like solubility, phosphoric acid uptake and mechanical properties, and test a membrane in a fuel cell, proving that the membranes are gas tight and show a good performance.

Original languageEnglish
Pages (from-to)409-417
Number of pages9
JournalJournal of Materials Chemistry A
Volume5
Issue number1
DOIs
Publication statusPublished - 2017

Fingerprint

Polysulfones
Crosslinking
Membranes
Friedel-Crafts reaction
Acids
Curing
Temperature
Sulfones
Nucleophiles
Diamines
Sulfonic Acids
Alkylating Agents
Phosphoric acid
Hot Temperature
polysulfone P 1700
Fuel cells
Hydrolysis
Nitrogen
Solubility
Gases

ASJC Scopus subject areas

  • Chemistry(all)
  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

Cite this

Joseph, D., Krishnan, N. N., Henkensmeier, D., Jang, J. H., Choi, S. H., Kim, H. J., ... Nam, S. (2017). Thermal crosslinking of PBI/sulfonated polysulfone based blend membranes. Journal of Materials Chemistry A, 5(1), 409-417. https://doi.org/10.1039/c6ta07653j

Thermal crosslinking of PBI/sulfonated polysulfone based blend membranes. / Joseph, Dickson; Krishnan, N. Nambi; Henkensmeier, Dirk; Jang, Jong Hyun; Choi, Sun Hee; Kim, Hyoung Juhn; Han, Jonghee; Nam, SukWoo.

In: Journal of Materials Chemistry A, Vol. 5, No. 1, 2017, p. 409-417.

Research output: Contribution to journalArticle

Joseph, D, Krishnan, NN, Henkensmeier, D, Jang, JH, Choi, SH, Kim, HJ, Han, J & Nam, S 2017, 'Thermal crosslinking of PBI/sulfonated polysulfone based blend membranes', Journal of Materials Chemistry A, vol. 5, no. 1, pp. 409-417. https://doi.org/10.1039/c6ta07653j
Joseph D, Krishnan NN, Henkensmeier D, Jang JH, Choi SH, Kim HJ et al. Thermal crosslinking of PBI/sulfonated polysulfone based blend membranes. Journal of Materials Chemistry A. 2017;5(1):409-417. https://doi.org/10.1039/c6ta07653j
Joseph, Dickson ; Krishnan, N. Nambi ; Henkensmeier, Dirk ; Jang, Jong Hyun ; Choi, Sun Hee ; Kim, Hyoung Juhn ; Han, Jonghee ; Nam, SukWoo. / Thermal crosslinking of PBI/sulfonated polysulfone based blend membranes. In: Journal of Materials Chemistry A. 2017 ; Vol. 5, No. 1. pp. 409-417.
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