2021 Annual Meeting
Investigation of the Impact of Equivalent Weight on 3M Proton Exchange Membrane Functionality
Polymer membranes are an integral component of Proton Exchange Membrane (PEM) fuel cells
and are therefore integral to advances in energy conversion and storage and a cleaner energy
future. Much research has been conducted on the class of membranes known as perfluorosulfonic
acid (PFSA) membranes due to their promising performance characteristics. Recently, many new
PFSA membranes with variations in structure, composition, and equivalent weight have been
synthesized and characterized in hopes of improving efficiency and reducing cost, currently the
major barriers to more widespread implementation. As side chain chemistry largely determines
membrane functionality, equivalent weight is an important parameter to explore. In this work,
the effect of equivalent weight on PFSA membrane properties was studied. Specifically, PFSA
membranes created by 3M with equivalent weights of 725, 825, and 1000 were tested to
determine conductivity, water sorption, and specific density. Conductivity was tested over a
range of temperatures and relative humidity levels simulating potential operating conditions.
Water sorption was tested over a range of relative humidity levels to gain an understanding of
how relative humidity affects membrane hydration, which is one of the primary factors
determining the rate of proton transport in the membrane. In addition, specific density was also
tested at these conditions, as density offers insight into membrane hydration and polymer
morphology. By studying membranes in this fashion, their performance can be objectively
assessed in a controlled environment prior to testing in PEM fuel cells. Membranes with lower
equivalent weight exhibited higher conductivity, higher water sorption, and lower specific
density. This suggests that for the range of 3M membranes studied, lower equivalent weights, i.e.
higher concentrations of sulfonic acid groups, contribute to better membrane performance.
Through these findings, this study attempts to further the understanding of the impact of side
chains on membrane functionality and guide membrane synthesis research moving forward.
and are therefore integral to advances in energy conversion and storage and a cleaner energy
future. Much research has been conducted on the class of membranes known as perfluorosulfonic
acid (PFSA) membranes due to their promising performance characteristics. Recently, many new
PFSA membranes with variations in structure, composition, and equivalent weight have been
synthesized and characterized in hopes of improving efficiency and reducing cost, currently the
major barriers to more widespread implementation. As side chain chemistry largely determines
membrane functionality, equivalent weight is an important parameter to explore. In this work,
the effect of equivalent weight on PFSA membrane properties was studied. Specifically, PFSA
membranes created by 3M with equivalent weights of 725, 825, and 1000 were tested to
determine conductivity, water sorption, and specific density. Conductivity was tested over a
range of temperatures and relative humidity levels simulating potential operating conditions.
Water sorption was tested over a range of relative humidity levels to gain an understanding of
how relative humidity affects membrane hydration, which is one of the primary factors
determining the rate of proton transport in the membrane. In addition, specific density was also
tested at these conditions, as density offers insight into membrane hydration and polymer
morphology. By studying membranes in this fashion, their performance can be objectively
assessed in a controlled environment prior to testing in PEM fuel cells. Membranes with lower
equivalent weight exhibited higher conductivity, higher water sorption, and lower specific
density. This suggests that for the range of 3M membranes studied, lower equivalent weights, i.e.
higher concentrations of sulfonic acid groups, contribute to better membrane performance.
Through these findings, this study attempts to further the understanding of the impact of side
chains on membrane functionality and guide membrane synthesis research moving forward.