title: Structural effect of glyme-Li(+) salt solvate ionic liquids on the conformation of poly(ethylene oxide).
abstract: The conformation of 36 kDa polyethylene oxide (PEO) dissolved in three glyme-Li(+) solvate ionic liquids (SILs) has been investigated by small angle neutron scattering (SANS) and rheology as a function of concentration and compared to a previously studied SIL. The solvent quality of a SIL for PEO can be tuned by changing the glyme length and anion type. Thermogravimetric analysis (TGA) reveals that PEO is dissolved in the SILs through Li(+)-PEO coordinate bonds. All SILs (lithium triglyme bis(trifluoromethanesulfonyl)imide ([Li(G3)]TFSI), lithium tetraglyme bis(pentafluoroethanesulfonyl)imide ([Li(G4)]BETI), lithium tetraglyme perchlorate ([Li(G4)]ClO4) and the recently published [Li(G4)]TFSI) are found to be moderately good solvents for PEO but solvent quality decreases in the order [Li(G4)]TFSI ∼ [Li(G4)]BETI > [Li(G4)]ClO4 > [Li(G3)]TFSI due to decreased availability of Li(+) for PEO coordination. For the same glyme length, the solvent qualities of SILs with TFSI(-) and BETI(-) anions ([Li(G4)]TFSI and [Li(G4)]BETI) are very similar because they weakly coordinate with Li(+), which facilitates Li(+)-PEO interactions. [Li(G4)]ClO4 presents a poorer solvent environment for PEO than [Li(G4)]BETI because ClO4(-) binds more strongly to Li(+) and thereby hinders interactions with PEO. [Li(G3)]TFSI is the poorest PEO solvent of these SILs because G3 binds more strongly to Li(+) than G4. Rheological and radius of gyration (Rg) data as a function of PEO concentration show that the PEO overlap concentrations, c* and c**, are similar in the three SILs.
authors.affiliation: Priority Research Centre for Advanced Fluids and Interfaces, Newcastle Institute for Energy and Resources, The University of Newcastle, Callaghan, NSW 2308, Australia. rob.atkin@newcastle.edu.au.
authors.forename: Zhengfei
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Priority Research Centre for Advanced Fluids and Interfaces, Newcastle Institute for Energy and Resources, The University of Newcastle, Callaghan, NSW 2308, Australia. rob.atkin@newcastle.edu.au.
authors.forename: Samila
authors.initials: S
authors.lastname: McDonald
authors.affiliation: School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Fitzgerald
authors.affiliation: School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia.
authors.forename: Gregory G
authors.initials: GG
authors.lastname: Warr
authors.affiliation: Priority Research Centre for Advanced Fluids and Interfaces, Newcastle Institute for Energy and Resources, The University of Newcastle, Callaghan, NSW 2308, Australia. rob.atkin@newcastle.edu.au.
authors.forename: Rob
authors.initials: R
authors.lastname: Atkin