Water dynamics in rigid ionomer networks.
N C Osti1, T N Etampawala1, U M Shrestha1
1Department of Chemistry, Clemson University, Clemson, South Carolina 29634, USA.
The Journal of Chemical Physics
|December 18, 2016
Summary
Sulfonated poly(phenylene) (SPP) membranes exhibit immobile polymer networks with dynamic water molecules. Water mobility in SPP increases with temperature and hydration, enabling selective transport across a wide temperature range.
Area of Science:
- Polymer Science
- Materials Science
- Neutron Scattering
Background:
- Ionic polymer networks, specifically sulfonated poly(phenylene) (SPP), possess unique rigid structures.
- Understanding water dynamics in these networks is crucial for applications like selective transport membranes.
Purpose of the Study:
- To investigate the dynamics of water molecules within rigid sulfonated poly(phenylene) (SPP) networks.
- To correlate water mobility with temperature, humidity, and ionic group concentration.
Main Methods:
- Quasi-elastic neutron scattering (QENS) was employed to probe water dynamics.
- Measurements were conducted across varying temperatures, ionic group fractions, and humidity levels.
Main Results:
- The polymer network of SPP was found to be immobile, while absorbed water molecules exhibited dynamic behavior.
- Water molecules occupied multiple sites, transitioning between bound and loosely constrained states.
- Increased temperature and hydration levels led to enhanced system dynamics.
- Water molecules remained mobile even below freezing temperatures.
Conclusions:
- SPP membranes maintain dynamic water populations irrespective of temperature, including subzero conditions.
- The observed water dynamics highlight the potential of SPP membranes for selective transport applications over an extensive temperature range.
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