Confinement of Ionic Liquid by Networked Polymers Based on Multifunctional Epoxy Resins

Abstract

Networked polymers confining an ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide (EMImTFSI), were prepared by curing a mixture of bisphenol A diglycidyl ether (BADGE) and tetrafunctional epoxy resins with tetraethylenepentamine (TEPA) in the presence of ionic liquid. It was found that addition of the tetrafunctional epoxy resins was inevitable for better ionic liquid confinement. The ionic liquid confinement, ionic conductivity, mechanical strength, and morphology of the materials strongly depended on the ionic liquid content. At a low ionic liquid content (<40 wt %), the material tightly confined the ionic liquid and showed little ionic conductivity with a high Young’s modulus, while at a high ionic liquid content (>40 wt %), it did not confine the ionic liquid showing higher ionic conductivity with a low Young’s modulus. At a high ionic liquid content (>40 wt %), microphase separation between the ionic liquid and the epoxy networked polymer was observed by scanning electron microscopy (SEM). A transition of the microphase separation from discrete sphere to continuous structure was also observed between 40 wt % and 50 wt % ionic liquid contents. This morphology transition caused a drastic change of the material properties around these ionic liquid contents.

Synthesis and Characterization of Epoxy/MCDEA Networks Modified with Imidazolium‐Based Ionic Liquids

“…The high price of ILs as well as their commercial availability limited to organic salts functionalized with short alkyl chains may be the main reasons. In fact, Matsumodo and Endo [14] employed different imidazolium-based ILs in epoxy networks cured with tetraethylene pentamine and observed a confinement of IL by the epoxy matrix. A similar system was patented by the same authors for preventing elution of IL from hardening components.…”

Composition as a Means To Control Morphology and Properties of Epoxy Based Dual-Phase Structural Electrolytes

“…31,33,[41][42][43][44] In addition, the properties/structure (morphology) of the epoxy/IL blends and resulting cured epoxies can be adjusted, for example to improve wear and scratch resistance, 32, 33 thermal stability 44 or ion conduction. 10,18 In an earlier study, we described a strong effect of the morphology on the properties of electrolytes based on a blend of an epoxy/amine system and a lithium salt doped IL 10 ; the conclusion was that a relatively coarse bicontinuous structure is the most promising for structural electrochemical applications. Here, we further tune the morphology to optimize the desirable combination of ionic conductivity and mechanical performance, using commercial epoxy resin and IL based electrolytes.…”

“…18,19 The interest in epoxy/amine systems is also driven by the excellent set of specific properties of the cured resins, including excellent mechanical properties as well as thermal and chemical stability. It has been shown in the literature 10,18 that the properties of the final structural electrolytes are affected by the microstructure of the polymer phase. As epoxies have the ability to form bicontinuous structures via polymerization induced phase separation, [20][21][22][23] this approach has been used to produce porous monoliths for chromatography and biomedical applications.…”

Ionic Liquids and Polymeric Ionic Liquids as Stimuli-Responsive Functional Materials

“…Ionic liquid confinement by epoxy resins has been examined [128] for C 2 ImC 1 NTf 2 , C 4 ImC 1 NTf 2 , and C 6 ImC 1 NTf 2 in resins based on bisphenol A diglycidyl ether (BADGE), N,N,N 0 ,N 0 -tetraglycidyl-diaminodiphenylmethane (MY-721), and N,N,N 0 ,N 0 -tetraglycidyl-m-xylenediamine (Tetrad-X). The glycidyl ether groups were cross-linked using tetraethylenepentamine (TEPA).…”

“…) at room temperature [128][129][130]. Rogers's group reported the first cross-linking reaction of disuccinimidylpropyl poly (ethylene glycol) (PEG) monomers with four-arm tetraamine PEG cross-linkers in the hydrophobic ionic liquid, C 6 ImC 1 NTf 2 [131].…”