SAXS signature of the lamellar ordering of ionic domains of perfluorinated sulfonic-acid ionomers by electric and magnetic field-assisted casting

Autor(es)

da Silva, Jaqueline S. ^[1] ; Carvalho, Sabrina G. M. ^[1] ; da Silva, Rodrigo P. ^[1] ; Tavares, Ana C. ^[2] ; Schade, Ulrich ^[3] ; Puskar, Ljiljana ^[3] ; Fonseca, Fabio C. ^[1] ; Matos, Bruno R. ^[1]

Afiliação do(s) autor(es)

^[1] IPEN CNEN SP, Inst Pesquisas Energet & Nucl, BR-05508000 Sao Paulo - Brazil

^[2] Inst Natl Rech Sci, Energie Mat & Telecommun INRS EMT, 1650 Blvd Lionel Boulet, Varennes, PQ J3X 1S2 - Canada

^[3] Helmholtz Zentrum Mat & Energie GmbH, Methoden Mat Twicklung, D-12489 Berlin - Germany

• Tipo de documento: Artigo Científico
• Fonte: Physical Chemistry Chemical Physics; v. 22, n. 24, p. 13764-13779, JUN 28 2020.
• Citações Web of Science: 3

Resumo

At present, small angle X-ray scattering (SAXS) studies of perfluorinated sulfonic-acid ionomers (PFSAs) are unable to fully determine the true shape of their building blocks, as recent SAXS modelling predicts disk- and rod-like nanoionic domains as being equally possible. This scenario requires evidence-based findings to unravel the real shape of PFSA building blocks. Herein, a SAXS pattern signature for a lamellar nanophase separation of the ionic domains of Nafion is presented, backed by mid and far infrared spectroscopy (MIR and FIR) and wide angle X-ray scattering (WAXS) data of Nafion in different ionic forms, a broad range of ionic phase contents (EW similar to 859-42 252 g eq(-1)) and temperatures. The study indicates that the lamellar arrangement of the ionic domains is the most representative morphology that accounts for the physical properties of this ionomer. The lamellar SAXS reflections of Nafion are enhanced in electric and magnetic field-aligned membranes, as confirmed by atomic force microscopy (AFM). Electric and magnetic field-assisted casting of Nafion allowed producing nanostructured and anisotropic films with the lamellas stacked perpendicularly to the field vector, which is the direction of interest for several applications. Such nanostructured Nafion membranes are bestowed with advanced optical and proton transport properties, making them promising materials for solar and fuel cells. (AU)

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