- Title
- Nanostructure of propylammonium nitrate in the presence of poly(ethylene oxide) and halide salts
- Creator
- Stefanovic, Ryan; Webber, Grant B.; Page, Alister J.
- Relation
- Journal of Chemical Physics Vol. 148, Issue 19, no. 193826
- Publisher Link
- http://dx.doi.org/10.1063/1.5012801
- Publisher
- AIP Publishing
- Resource Type
- journal article
- Date
- 2018
- Description
- Nanoscale structure of protic ionic liquids is critical to their utility as molecular electrochemical solvents since it determines the capacity to dissolve salts and polymers such as poly(ethylene oxide) (PEO). Here we use quantum chemical molecular dynamics simulations to investigate the impact of dissolved halide anions on the nanostructure of an archetypal nanostructured protic ionic liquid, propylammonium nitrate (PAN), and how this impacts the solvation of a model PEO polymer. At the molecular level, PAN is nanostructured, consisting of charged/polar and uncharged/nonpolar domains. The charged domain consists of the cation/anion charge groups, and is formed by their electrostatic interaction. This domain solvophobically excludes the propyl chains on the cation, which form a distinct, self-assembled nonpolar domain within the liquid. Our simulations demonstrate that the addition of Cl- and Br- anions to PAN disrupts the structure within the PAN charged domain due to competition between nitrate and halide anions for the ammonium charge centre. This disruption increases with halide concentration (up to 10 mol. %). However, at these concentrations, halide addition has little effect on the structure of the PAN nonpolar domain. Addition of PEO to pure PAN also disrupts the structure within the charged domain of the liquid due to hydrogen bonding between the charge groups and the terminal PEO hydroxyl groups. There is little other association between the PEO structure and the surrounding ionic liquid solvent, with strong PEO self-interaction yielding a compact, coiled polymer morphology. Halide addition results in greater association between the ionic liquid charge centres and the ethylene oxide components of the PEO structure, resulting in reduced conformational flexibility, compared to that observed in pure PAN. Similarly, PEO self-interactions increase in the presence of Cl- and Br- anions, compared to PAN, indicating that the addition of halide salts to PAN decreases its utility as a molecular solvent for polymers such as PEO.
- Subject
- propylammonium nitrate; poly(ethylene oxide); halide salts; nanstructure
- Identifier
- http://hdl.handle.net/1959.13/1404752
- Identifier
- uon:35397
- Identifier
- ISSN:0021-9606
- Rights
- This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Journal of Chemical Physics, Vol. 148, Issue 19, Number 193826 and may be found at https://aip.scitation.org/doi/10.1063/1.5012801
- Language
- eng
- Full Text
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