Abstract
The dynamics of water within ionic polymer networks formed by sulfonated poly(phenylene) (SPP), as revealed by quasi-elastic neutron scattering (QENS), is presented. These polymers are distinguished from other ionic macromolecules by their rigidity and therefore in their network structure. QENS measurements as a function of temperature as the fraction of ionic groups and humidity were varied have shown that the polymer molecules are immobile while absorbed water molecules remain dynamic. The water molecules occupy multiple sites, either bound or loosely constrained, and bounce between the two. With increasing temperature and hydration levels, the system becomes more dynamic. Water molecules remain mobile even at subzero temperatures, illustrating the applicability of the SPP membrane for selective transport over a broad temperature range.
| Original language | English |
|---|---|
| Article number | 224901 |
| Journal | Journal of Chemical Physics |
| Volume | 145 |
| Issue number | 22 |
| DOIs | |
| State | Published - Dec 14 2016 |
Funding
This work was supported by the U.S. Department of Energy under the Contract Nos. DOE-DE-FG02-07ER46456 and DE-FG02-12ER46843. The use of neutron scattering facility at Oak Ridge National Laboratory is supported by the U.S. Department of Energy, Office of Basic Energy Sciences. Travel to Oak Ridge National Laboratory to carry out this work was supported by a Travel Fellowship from the DOE-EPSCoR Grant to the University of Tennessee, DE-FG02-08ER46528. This work utilized facilities supported in part by the National Science Foundation under Agreement No. DMR-0944772. We acknowledge the support of the National Institute of Standards and Technology, U.S. Department of Commerce, in providing the neutron research facilities used in this work. Any mention of commercial products within NIST web pages is for information only; it does not imply recommendation or endorsement by NIST.