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Merging Ion Concentration Polarization between Juxtaposed Ion Exchange Membranes to Block the Propagation of the Polarization Zone
Published on: February 23, 2017
Microheterogeneity in native and cation-exchanged Nafion membranes.
E Siva Subramaniam Iyer1, Anindya Datta
1Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, India 400076.
The Journal of Physical Chemistry. B
|August 2, 2012
Summary
This study uses 2-(4'-Pyridyl)benzimidazole (4PBI) to probe Nafion membrane water channels. 4PBI selectively protonates different sites, differentiating cation-exchanged membranes at varying hydration levels.
Area of Science:
- Materials Science
- Polymer Chemistry
- Physical Chemistry
Background:
- Nafion membranes are crucial for electrochemical applications, requiring understanding of their internal water structure.
- Investigating the microheterogeneity of water nanochannels is key to optimizing membrane performance.
- Existing fluorescent probes have limitations in differentiating specific environments within Nafion.
Purpose of the Study:
- To utilize 2-(4 omino-Pyridyl)benzimidazole (4PBI) as a fluorescent probe for Nafion microheterogeneity.
- To differentiate between native and cation-exchanged Nafion membranes.
- To assess probe behavior at varying hydration levels.
Main Methods:
- Utilized 2-(4 omino-Pyridyl)benzimidazole (4PBI) as a fluorescent probe.
- Investigated native and cation-exchanged Nafion membranes (H+, (CH3)4N+, Na+).
- Analyzed protonation sites of 4PBI at different hydration levels.
Main Results:
- 4PBI selectively protonates either the pyridyl or benzimidazole nitrogen based on the membrane's cation.
- Native and (CH3)4N+ exchanged membranes show preferential pyridyl nitrogen protonation.
- Na+ exchanged membranes exhibit selective benzimidazole nitrogen protonation.
- 4PBI successfully differentiates cation-exchanged membranes across hydration levels.
Conclusions:
- 4PBI is a sensitive fluorescent probe for Nafion water nanochannel microheterogeneity.
- The probe's protonation behavior reveals distinct local environments in different Nafion membranes.
- 4PBI offers an advantage over previous probes for characterizing cation-exchanged Nafion membranes.
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