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Open AccessArticle

Effect of Noncovalent Dispersion of Poly(Ethylene Oxide) in Columnar Polyether-Based Discotic Liquid Crystal on the Ionic Conductivity and Dynamics of Lithium Ions

Department of Chemistry, National Sun Yat Sen University, Kaohsiung 804, Taiwan
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Crystals 2019, 9(12), 627; https://doi.org/10.3390/cryst9120627
Received: 11 November 2019 / Revised: 23 November 2019 / Accepted: 26 November 2019 / Published: 28 November 2019
(This article belongs to the Special Issue Liquid-Crystalline Ion Conductors)
The ionic conductivity of an electrolyte is represented by a product of carrier density, charge (electric), and ionic mobility. The overall goal of this study was to provide an insight into the influence of lithium ion conductivity and dynamic when a continuous discotic liquid crystal (DLC) matrix of hexaazatrinapthylene-polyether, HATN-TEG-1, is doped with a small amount of polyethylene oxide (PEO, 5% of MW 8000). The favorable non-covalent interactions between PEO and the DLC triethylene glycol side-chains is supported by the maintenance of the mesophase. The lithium ionic conductivity of HATN-TEG-1 was found to be 1.1 × 10−6 S cm−1, which is better than the corresponding HATN-TEG-1-5%PEO-8000 with a value of 6.06 × 10−7 S cm−1. These results are further supported by the dynamics of the lithium ions in HATN-TEG-1 and HATN-TEG-1-5%PEO-8000 as characterized by 7Li, and 1H NMR spin-lattice relaxation time and self-diffusion coefficient measurements. Though the additional PEO was found to increase the ion carriers, the significant lowering of the ionic conductivity may be attributed to the more pronounced decrease of the mobility of the ionic part when the HATN-TEG-1 matrix is dispersed with PEO. This finding indicates that the doping of 5% PEO onto the matrix of HATN-TEG-1 DLC has an adverse effect on both its diffusion rate and ion conductivity. View Full-Text
Keywords: discotic liquid crystal; polyethylene oxide dispersion; Ionic conductivity; mobility and diffusion coefficients; solid-state 1H and 7Li NMR discotic liquid crystal; polyethylene oxide dispersion; Ionic conductivity; mobility and diffusion coefficients; solid-state 1H and 7Li NMR
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MDPI and ACS Style

Hwang, J.-D.; Chen, P.-Y.; Ding, S.-W.; Ong, C.W. Effect of Noncovalent Dispersion of Poly(Ethylene Oxide) in Columnar Polyether-Based Discotic Liquid Crystal on the Ionic Conductivity and Dynamics of Lithium Ions. Crystals 2019, 9, 627.

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