Issue 8, 2018

Syntheses, characterizations and functions of cationic polyethers with imidazolium-based ionic liquid moieties

Abstract

Cationic polyethers with imidazolium-based ionic liquid moieties were synthesized and characterized thoroughly for their properties and functions. Poly(epichlorohydrin) (poly(ECH)) was quaternized by 1-methylimidazole to provide poly(N-glycidyl-N′-methylimidazolium chloride) (poly(ECH-MeIm+Cl)). Anion exchange of the poly(ECH-MeIm+Cl) with Li salts provided other cationic polyethers: hydrophobic poly(N-glycidyl-N′-methylimidazolium bis(trifluoromethanesulfonyl)imide) (poly(ECH-MeIm+TFSI)) and hydrophilic poly(N-glycidyl-N′-methylimidazolium tetrafluoroborate) (poly(ECH-MeIm+BF4)). The 5% thermal decomposition temperatures of these cationic polyethers are quite high (300–400 °C). Contrary to poly(ECH) (glass transition temperature (Tg) = −49 °C), the poly(ECH-MeIm+Cl) is a polymer plastic (Tg = 92 °C) when completely dry. Poly(ECH-MeIm+TFSI) is elastomeric (Tg = −12 °C), whereas poly(ECH-MeIm+BF4) is a plastic (Tg = 67 °C). Poly(ECH-MeIm+Cl) rapidly absorbed a large amount of moisture from the atmosphere, changing its appearance from solid to a viscous fluid even under relatively dry conditions (23 °C, and 40% relative humidity (RH); water uptake = 29 wt%), suggesting its highly deliquescent nature. The hydrated poly(ECH-MeIm+Cl) possesses neither a glass transition nor a phase transition between −60 °C and 80 °C. The ionic conductivity of the hydrated polymer is as high as 1.8 × 10−2 S cm−1 under humid conditions (23 °C, and 80% RH; water uptake = 72 wt%) and is dependent mainly on water uptake. The miscibility between the cationic polyethers and ionic liquids is quite high; mixtures of ethylmethylimidazolium bis(trifluoromethanesulfonyl)imide and the cationic polyethers had no phase transitions between −70 °C and 100 °C. Since the cationic polyethers were miscible with each other to exchange anions, random copolymers with desired copolymerization ratios can be prepared through simple mixing.

Graphical abstract: Syntheses, characterizations and functions of cationic polyethers with imidazolium-based ionic liquid moieties

Supplementary files

Article information

Article type
Paper
Submitted
24 noy 2017
Accepted
24 yan 2018
First published
24 yan 2018
This article is Open Access
Creative Commons BY-NC license

Polym. Chem., 2018,9, 948-960

Syntheses, characterizations and functions of cationic polyethers with imidazolium-based ionic liquid moieties

S. Hayano, K. Ota and H. T. Ban, Polym. Chem., 2018, 9, 948 DOI: 10.1039/C7PY01985H

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