Structural and dynamical aspects of PEG/LiClO₄ in solvent mixtures via NMR spectroscopy

Abstract

Motivated by the potential usefulness of polyethylene glycol (PEG)/Li+ salt mixtures in several industrial applications, we investigated the structure and dynamics of PEG/LiClO4 mixtures in D2O and its mixtures with CD3CN and DMSO‐d6, in a series of PEG‐based polymers with a wide variation in their molecular weights. 1H NMR chemical shifts, T1/T2 relaxation rates, pulsed‐field gradient NMR diffusion experiments, and 2D HOESY NMR studies have been performed to understand the structural and dynamical aspects of these mixtures. Increasing the temperature of the medium results in a significant perturbation in the H‐bonded structure of PEG in its PEG/LiClO4/D2O mixtures as observed from the increase in chemical shifts. On the other hand, the addition of molecular cosolvents has a negligible effect. The hydrodynamic structure of PEG shows a pronounced variation at low temperature with increasing molecular weight, which, however, disappears at higher temperatures. Increasing the temperature leads to a decrease in the hydrodynamic structure of PEG, which can be explained on the basis of solvation–desolvation phenomena. The 2D HOESY NMR spectra reveal a new finding of Li+‐water binding in the PEG/LiClO4/D2O mixtures with the addition of molecular solvents, suggesting that the Li+ cation diffuses freely in the D2O mixtures of polymers as compared with the polymer mixtures with DMSO or CD3CN.

Design of Localized High-Concentration Electrolytes via Donor Number

“…More recently, solvating power was proposed as a measure to evaluate the relative coordination ability of solvents. The determination of a solvent’s solvating power was reported through either NMR measurements or simulations . However, the former relies on two internal references, with the reference–solvent interaction being ignored, while the latter lacks standard protocol. − So far, the number of reported solvating power values is rather limited (<20), and they cannot be compared cross different literature sources (see Table S1).…”

“…The determination of a solvent’s solvating power was reported through either NMR measurements or simulations . However, the former relies on two internal references, with the reference–solvent interaction being ignored, while the latter lacks standard protocol. − So far, the number of reported solvating power values is rather limited (<20), and they cannot be compared cross different literature sources (see Table S1). Besides, the Kamlet–Taft Lewis basicity was used to correlate with the solvation structures of LHCEs based on 14 samples .…”

Dynamics of the mixtures of fullerene‐60 and aromatic solvents: A molecular dynamics approach

“…In each simulation, 15 molecules of the fullerene C60 are considered. In each simulation, the solvent and solute molecules are randomly inserted in a cubical box of dimension 5×5×5 nm 3 . The value of cutoff for shortrange electrostatic and Van-der-Waal's potential is 1 nm.…”

“…The carbon atom has a unique ability to participate in robust covalent bonds with the other carbon atoms in various hybridization states, namely, sp, sp 2 , and sp 3 . This property enables them to form different types of structures, namely, long chain polymers and beautiful structured allotropes [1][2][3] and is one of great importance in organic and biochemistry. [4] Over the past few decades, carbon nanoparticles have received a great interest from biologists, chemists, and physicists.…”