Electrostatic interactions of Ionomer Films as Probed by Variable Temperature Synchrotron Infrared Spectroscopy
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2018
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CONGRESSO BRASILEIRO DE ENGENHARIA E CIÊNCIA DOS MATERIAIS, 23.
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Resumo
The state of the art polymer electrolyte of Proton Exchange Membrane Fuel Cells
(PEM), Nafion®, has poor mechanical and electrical properties at T > 100 °C.
Specifically, long-term operation leads to irreversible performance losses that are
related to an irreversible modification of the ionomer morphology above the
temperature of alpha-transition (Talpha ~ 110 °C). Previous characterizations showed
that the alpha-transition is dependent on the different states of covalent and ionic
interactions among sulfonic acid groups, such as: ionic repulsions among RSO3-,
dipolar attractions among RSO3H dipoles, hydrogen bonding of sulfonic groups with
bulk and coordinated water molecules. The identification of both the functional groups
interactions in the MIR bands and the “ion-hopping bands” in the FIR bands for
annealed Nafion samples can give new insights into the role played by the ionic
interactions on the alpha of ionomer membranes. Such approach for understanding
the relationship between the dynamics of aplha-relaxation and Nafion morphology is
missing in the literature, possibly due to the incipient number of FIR studies of Nafion.
The central objective of this work is to advance the understanding of the chemical
features involved during the aplha-transition of in situ annealed Nafion membranes
with the high-resolution mid (MIR) and far (FIR) infrared spectroscopy using the IRIS
beamline of BESSY II synchrotron light source. Herein, the effect of short-term
annealing of Nafion at RH ~ 0% and selected temperatures below and above the alphatransition
is presented. The comparison between SAXS and FTIR data of Nafion
membranes annealed in situ revealed that the alpha-transition is due to the long range
motion of the ionomer chains via weakening of electrostatic interactions of the ionomer
functional groups.
Como referenciar
SILVA, J.S. da; MATOS, B.R.; SCHADE, U.; PUSKAR, L.; FONSECA, F.C. Electrostatic interactions of Ionomer Films as Probed by Variable Temperature Synchrotron Infrared Spectroscopy. In: CONGRESSO BRASILEIRO DE ENGENHARIA E CIÊNCIA DOS MATERIAIS, 23., 04-08 de novembro, 2018, Foz do Iguaçu, PR. Resumo... p. 8626-8626. Disponível em: http://repositorio.ipen.br/handle/123456789/29673. Acesso em: 12 May 2024.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.