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Effect on bending behavior of counter cation species in perfluorinated sulfonate membrane–platinum composite
Author(s) -
Abe Yoshihiko,
Mochizuki Akira,
Kawashima Tooru,
Yamashita Shuzou,
Asaka Kinji,
Oguro Keisuke
Publication year - 1998
Publication title -
polymers for advanced technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.61
H-Index - 90
eISSN - 1099-1581
pISSN - 1042-7147
DOI - 10.1002/(sici)1099-1581(199808)9:8<520::aid-pat791>3.0.co;2-g
Subject(s) - materials science , membrane , composite material , nafion , anode , composite number , sulfonate , metal , platinum , cathode , electrochemistry , chemistry , electrode , sodium , catalysis , metallurgy , organic chemistry , biochemistry
The perfluorinated sulfonate membrane (Nafion ®117)–platinum composites having H + , mono‐ and bivalent metal ions as counter cations in the membranes were prepared and the bending behaviors of the composites actuated by the step voltage were investigated in deionized water. The bending behaviors of all composites have the same tendency as the composites to bend quickly to the anode side just after applying the step voltage and gradually to bend back to the cathode side in spite of keeping on the application. However, they show differences in the bending rate and the maximum displacement to the anode side just after applying the step voltage, which are influenced by counter cation species in the membrane. In particular, the composite having Li + has the largest maximum displacement (about 1.1 mm) to the anode side. The relationship between the maximum displacements of the composites and water states in the membranes were studied. The maximum displacements of the composites depend on the water content in the membranes. In both series of the composites having mono‐ and bivalent metal ions, the maximum displacements increase with increasing water content, except the composites having Rb + and Sr 2+ which belong to fifth period in the periodic table. In spite of the result that the water content in the membrane having H + , which is about 20wt%, is nearly equal to that in the membrane having Na a , the maximum displacement of the composite having H + is only about one‐third as large as that of the composite having Na + . The water structures in the membranes were investigated by using differential scanning calorimetry (DSC). The DSC endothermograms obtained indicate that the freezing water in the membrane having H + has a much stronger interaction with sulfonate groups and counter cations than that in the membrane having Na + . It is concluded that the content and structure of the freezing water in the membrane have a profound effect on the bending behavior of the composite. © 1998 John Wiley & Sons, Ltd.