NIST logo

Publication Citation: Interfacial morphology and water transport of proton-conducting polymer membranes in fuel cell

NIST Authors in Bold

Author(s): Sangcheol Kim; Joseph A. Dura; Kirt A. Page; Christopher L. Soles;
Title: Interfacial morphology and water transport of proton-conducting polymer membranes in fuel cell
Published: July 05, 2013
Abstract: We quantify the interfacial structure and corresponding water transport kinetics in thin films of Nafion using neutron reflectivity (NR) and quartz-crystal microbalance (QCM) by integrating these measurements with in-situ, controlled relative humidity chambers. Rigorous fitting of the NR profiles under humidified conditions reveals that a hydrophilic organosilicate substrate induces an interfacial layering of the water transport channels in Nafion parallel to the substrate whereas hydrophobic analogs does not trigger this interfacial ordering. The interfacial layering on the hydrophilic substrate leads to an excess in the total water mass uptake that is verified by QCM measurements. The excess of water in thin Nafion films are quantitatively consistent with the segregation amounts and length scales quantified by NR. However, there is little difference in the transport kinetics between the hydrophilic and hydrophobic substrates, implying that the preferential orientation of the water transport domains parallel to the hydrophilic substrate has little effect on the transport kinetics of water ingress/egress out of the film.
Citation: Advanced Materials
Volume: 46
Pages: pp. 5630 - 5637
Keywords: Interfacial structure, water transport kinetics, thin film, surface energy, reflectivity
Research Areas: Soft Condensed Matter, Energy Conversion, Storage, and Transport, Polymers
DOI: http://dx.doi.org/10.1021/ma400750f  (Note: May link to a non-U.S. Government webpage)
PDF version: PDF Document Click here to retrieve PDF version of paper (2MB)