Ionic Conductivity of β‐Cyclodextrin–Polyethylene‐Oxide/Alkali‐Metal‐Salt Complex

Abstract

Highly conductive, crystalline, polymer electrolytes, β-cyclodextrin (β-CD)-polyethylene oxide (PEO)/LiAsF6 and β-CD-PEO/NaAsF6 , were prepared through supramolecular self-assembly of PEO, β-CD, and LiAsF6 /NaAsF6 . The assembled β-CDs form nanochannels in which the PEO/X(+) (X=Li, Na) complexes are confined. The nanochannels provide a pathway for directional motion of the alkali metal ions and, at the same time, separate the cations and the anions by size exclusion.

Supramolecular Self-Assembly of Methylated Rotaxanes for Solid Polymer Electrolyte Application

“…Within this work we compare ion transport properties of nonmodified CD/PEO and methylated CD/PEO complexes and their applicability as SPEs in LMBs. Based on combined computational and experimental efforts, we show that the Li-ion transport in the considered complexes is quite different from anticipated mechanisms, , thereby revealing that major contributions to ionic conductivity originate from lithium ions moving outside the present nanochannels rather than inside along the polymer chain(s), thus limiting the impact of polymer segmental dynamics . Also, methylation of CDs leads to almost 2 orders of magnitude higher ionic conductivity and three times higher transport number compared to nonmodified complexes, thus highlighting rational design strategies for future SPEs with superior properties, aiding other transport mechanisms than the traditional. , …”

“…Supramolecular self-assembled structures as building blocks of functional aggregates have had a large impact on many research fields in chemistry and attracted even more interest when concepts for self-assembly of polymers were introduced that exploit (noncovalent) intermolecular interactions to achieve three-dimensional control of complex architectures. − In particular, self-assembly of polyrotaxanes (PRs) and polypseudorotaxanes (PPRs) where molecular rings (host molecule) are threaded onto a macromolecular chain (guest molecule) via noncovalent host–guest interactions in aqueous solution yields systems with great potential as stimulus-responsive materials, molecular machines, or switches in the fields of nanotechnology and drug delivery. − Cyclodextrins (CDs) with lipophilic inner cavities and hydrophilic outer surfaces have been extensively studied as host molecules mainly due to their bioavailability, low cytotoxicity, as well as capability of readily forming inclusion complexes with a variety of guest molecules, including poly­(ethylene oxide) (PEO) and its derivatives. ,− The head–tail/tail–head sequence of CD shown in Figure a represents the ideal structure with lowest energy . The major driving force for successful self-assembly comprises hydrophobic and van der Waals interactions between the polymer and CDs as well as hydrogen bonds between adjacent CD molecules.…”

NMR Study on the Roles of Li+ in the Cellulose Dissolution Process

“…It indicates that a part of Li + ions combined with cellulose chains directly in the LiOH/cellulose system. − It is the first time to obtain a direct result to prove the relationship between Li + and cellulose on the molecular level. We can speculate that after OH – ions play a role to split the intermolecular hydrogen bond between cellulose chains, a part of Li + ions combines with the oxygen groups of cellulose, , and the rest of Li + exists in the system as Li + –OH – and free Li + existing forms. The process is the main reason that the alkali aqueous solution can partially dissolve cellulose.…”