Confinement-Driven Increase
in Ionomer Thin-Film Modulus
Kirt A. Page
Ahmet Kusoglu
Christopher M. Stafford
Sangcheol Kim
R. Joseph Kline
Adam Z. Weber
10.1021/nl501233g.s001
https://acs.figshare.com/articles/journal_contribution/Confinement_Driven_Increase_in_Ionomer_Thin_Film_Modulus/2297407
Ion-conductive
polymers, or ionomers, are critical materials for
a wide range of electrochemical technologies. For optimizing the complex
heterogeneous structures in which they occur, there is a need to elucidate
the governing structure–property relationships, especially
at nanoscale dimensions where interfacial interactions dominate the
overall materials response due to confinement effects. It is widely
acknowledged that polymer physical behavior can be drastically altered
from the bulk when under confinement and the literature is replete
with examples thereof. However, there is a deficit in the understanding
of ionomers when confined to the nanoscale, although it is apparent
from literature that confinement can influence ionomer properties.
Herein we show that as one particular ionomer, Nafion, is confined
to thin films, there is a drastic increase in the modulus over the
bulk value, and we demonstrate that this stiffening can explain previously
observed deviations in materials properties such as water transport
and uptake upon confinement. Moreover, we provide insight into the
underlying confinement-induced stiffening through the application
of a simple theoretical framework based on self-consistent micromechanics.
This framework can be applied to other polymer systems and assumes
that as the polymer is confined the mechanical response becomes dominated
by the modulus of individual polymer chains.
2014-05-14 00:00:00
polymer systems
stiffening
framework
confinement effects
nanoscale dimensions
polymer chains
electrochemical technologies
bulk value
materials response
water transport
materials properties
modulu
ionomer properties