%0 Journal Article
%A Modestino, Miguel
A.
%A Kusoglu, Ahmet
%A Hexemer, Alexander
%A Weber, Adam Z.
%A Segalman, Rachel A.
%D 2012
%T Controlling Nafion Structure
and Properties via Wetting Interactions
%U https://acs.figshare.com/articles/journal_contribution/Controlling_Nafion_Structure_and_Properties_via_Wetting_Interactions/2515195
%R 10.1021/ma300212f.s001
%2 https://ndownloader.figshare.com/files/4158124
%K electrochemical applications
%K Thin films cast
%K morphology
%K ionomer
%K Controlling Nafion Structure
%K GISAXS
%K SiO 2 result
%X Proton conducting ionomers are widely used for electrochemical
applications including fuel-cell devices, flow batteries, and solar-fuels
generators. For most applications the presence of interfacial interactions
can affect the structure and properties of ionomers. Nafion is the
most widely used ionomer for electrochemical applications due to their
remarkable proton conductivity and stability. While Nafion membranes
have been widely studied, the behavior and morphology of this ionomer
under operating conditions when confined to a thin-film morphology
are still not well understood. Using in situ grazing-incidence
small-angle X-ray scattering (GISAXS) techniques, this work demonstrates
that the wetting interaction in thin-film interfaces can drastically
affect the internal morphology of ionomers and in turn modify its
transport properties. Thin films cast on hydrophobic substrates result
in parallel orientation of ionomer channels that retard the absorption
of water from humidified environments; while films prepared on SiO2 result in isotropic orientation of these domains, thus favoring
water sorption and swelling of the polymer. Furthermore, the results
presented in this paper demonstrate that upon thermal annealing of
Nafion thin films static crystalline domains form within the polymer
matrix that restrict further water uptake. The results presented in
this study can aid in the rational design of functional composite
materials used in fuel-cell catalyst layers and solar-fuels devices.
%I ACS Publications