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Thermal desorption and pyrolysis direct analysis in real time mass spectrometry of Nafion membrane
Author(s) -
Yamaguchi Makoto
Publication year - 2021
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.50172
Subject(s) - nafion , membrane , chemistry , mass spectrometry , thermogravimetry , thermal decomposition , decomposition , desorption , pyrolysis , electrolyte , ionomer , analytical chemistry (journal) , thermal desorption , chemical engineering , polymer , polymer chemistry , inorganic chemistry , electrochemistry , organic chemistry , chromatography , copolymer , adsorption , electrode , biochemistry , engineering
Perfluorosulfonic acid ionomer membranes have been widely used as proton conducting membranes in various electrochemical processes such as polymer electrolyte fuel cells and water electrolysis. While their thermal stability has been studied by thermogravimetry and analysis of low molecular weight products, their decomposition mechanism is little understood. In this study a newly developed methodology of thermal desorption and pyrolysis in combination with direct analysis in real time mass spectrometry is applied for Nafion membrane. An ambient ionization source and a high‐resolution time‐of‐flight mass spectrometer enabled unambiguous assignment of gaseous products. Thermal decomposition is initiated by side chain detachment above 350°C, which leaves carbonyls on the main chain at the locations of the side chains. Perfluoroalkanes are released above 400°C by main chain scission and their further decomposition products dominate above 500 °C. DFT calculation of reaction energies and barrier heights of model compounds support proposed decomposition reactions.