Structural Analysis of a Perfluorosulfonate Ionomer in Solution by 19F and 13C NMR

We demonstrate 19F and 13C NMR assignments and study of the structure in solution of Nafion, a perfluorosulfonate ionomer. Using 19F−13C HSQC, 19F−13C CIGAR-HMBC, and 19F−19F COSY to the model compounds of Nafion, we determine 19F and 13C assignments of model compounds. The combination of the three 2D NMR experiments represents an entirely new approach to analysis of perfluorinated organic compounds. On the basis of the assignments of the model compounds and also based on 19F coupled and 19F complete decoupled 13C NMR for Nafion, 19F and 13C NMR assignments are determined for Nafion. In this study the two 13C signals (OCF2) in the side chain separate more clearly relative to previously reported results. We also carried out MALDI-MS for Nafion, supporting the results found in NMR. From the result of NMR, it is suggested that the aggregates of Nafion in solution exist, and the structure of the aggregates is estimated.