Lithium-ion coordination-induced conformational change of PEG chains in ionic-liquid-based electrolytes

We report the structure of poly(ethylene glycol) (PEG) in a imidazolium-based ionic liquid (IL) electrolyte containing lithium bis(trifluoromethanesulfonyl)amide (LiTFSA) salt, as determined using Raman spectroscopy, high-energy X-ray total scattering (HEXTS), and molecular dynamics (MD) simulations...

Ausführliche Beschreibung

Gespeichert in:
Bibliographische Detailangaben
Veröffentlicht in:Physical chemistry chemical physics : PCCP 2020-03, Vol.22 (1), p.5561-5567
Hauptverfasser: Kamiyama, Yuji, Shibata, Masayuki, Kanzaki, Ryo, Fujii, Kenta
Format: Artikel
Sprache:eng
Schlagworte:
Online-Zugang:Volltext
Tags: Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
Beschreibung
Zusammenfassung:We report the structure of poly(ethylene glycol) (PEG) in a imidazolium-based ionic liquid (IL) electrolyte containing lithium bis(trifluoromethanesulfonyl)amide (LiTFSA) salt, as determined using Raman spectroscopy, high-energy X-ray total scattering (HEXTS), and molecular dynamics (MD) simulations. The Raman spectral study indicated that the TFSA anions bound to Li ions are desolvated when PEG is added to the LiTFSA/IL solution to form stable Li + -PEG complexes. Via quantitative analysis of the obtained Raman spectra, the desolvation number of the TFSA [ n d , per one oxygen atom of the ethylene glycol unit (O peg )] was determined to be ∼0.4, irrespective of the shape (star or linear) and molecular weight of the polymer. On the basis of radial distribution functions obtained from the HEXTS experiments and MD simulations, we demonstrated that the Li + -PEG complexation induces a conformational change of the PEG chain from gauche / anti -conformers to a syn conformer. This Li + -coordination-induced conformation resulted in a decrease in the radius of gyration ( R g ) of the PEG chain, implying a folding behavior of polymer chains through multiple O peg Li + O peg interactions. Li ion coordination-induced conformational change of poly(ethylene glycol) in ionic liquids.
ISSN:1463-9076
1463-9084
DOI:10.1039/c9cp06717e