Scientific Achievement
Demonstrated that favorable cation-ligand interactions tend to enhance salt partitioning into 12-Crown-4-functionalized polymer membranes but decrease salt diffusivity.
Image: More favorable interactions (moving left) increase salt partitioning (left plot) but decrease salt diffusivity relative to solution (right plot). Solid black lines are model predictions.
Significance and Impact
This work illustrates that ligand functionalization provides a route to altering the selectivity of polymer membranes. We illustrate the influence of such interactions on using molecular dynamics simulations and rationalize the results using analytical arguments.
Image: More favorable interactions (moving left) increase salt partitioning (left plot) but decrease salt diffusivity relative to solution (right plot). Solid black lines are model predictions.
Research Details
- Used molecular dynamics simulations to reveal the structure and distribution of cations and anions within polymer membranes functionalized with 12-Crown-4. Cations with lower hydration free energy are observed to complex more with 12-Crown-4.
- These interactions lead to more favorable salt transfer free energies and lower normalized diffusivities, in qualitative agreement with our analytical model.
Acknowledgements
This work was supported as part of the Center for Materials for Water and Energy Systems (M-WET), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Award #DE-SC0019272. V.G. acknowledges partial support from the Robert A. Welch Foundation (F-1599). The results in this paper were generated by using high-performance computing resources provided by The University of Texas at Austin Texas Advanced Computing Center. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant 000392968. We thank Dr. M. Scott Shell, Dr. Matej Kanduč, Rahul Sujanani, Sally Jiao, and Dennis R. Brown for their thoughtful insights and productive discussions.
Related Publication
Everett S. Zofchak, Zidan Zhang, Nico Marioni, Tyler J. Duncan, Harbor S. Sachar, Alyssa Chamseddine, Benny D. Freeman, and Venkat Ganesan, "Cation-Ligand Interactions Dictate Salt Partitioning and Diffusivity in Ligand-Functionalized Polymer Membranes," Macromolecules, 55(6), 2260-2270, 2022 March 4, https://doi.org/10.1021/acs.macromol.2c00035.