Preparation of Supramolecular Ionic Liquid Gels Based on Host

Mar 21, 2019 - In recent years, ionic liquid gels (IGs),1,2 which were obtained by swelling .... (L), capacitance (C), and resistance (R)) meter with ...
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Preparation of Supramolecular Ionic Liquid Gels Based on Host− Guest Interactions and Their Swelling and Ionic Conductive Properties Garry Sinawang,† Yuichiro Kobayashi,§ Yongtai Zheng,§ Yoshinori Takashima,*,†,‡ Akira Harada,*,§ and Hiroyasu Yamaguchi*,† Department of Macromolecular Science, Graduate School of Science and §Project Research Center for Fundamental Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan ‡ Osaka University Institute for Advanced Co-Creation Studies, Osaka University, 1-1 Yamadaoka, Suita, Osaka 565-0871, Japan Macromolecules Downloaded from pubs.acs.org by UNIV PARIS-SUD on 04/01/19. For personal use only.

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S Supporting Information *

ABSTRACT: Ionic liquid gels (IGs) have received much attention due to their electrochemical properties. IGs previously reported were formed by chemically cross-linked structures. The ionic conductivity (σ) of chemically cross-linked IGs was one order of magnitude lower than that of the native ionic liquid. Supramolecular polymeric IGs based on noncovalent bond cross-linkers have the potential to realize higher σ values. We prepared supramolecular polymeric IGs based on host−guest interactions. The supramolecular polymeric IG was prepared from bulk copolymerization of the host−guest complex between peracetylated γ-cyclodextrin (PAcγCD) and 2-ethyl-2-adamantane (Ad) in the presence of acrylate followed by immersing the copolymer in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIm TFSI). The σ value of the supramolecular polymeric IG was higher than those of the chemically cross-linked IGs. Although the σ values of the chemically cross-linked IG, Ad with chemically cross-linked IG, and PAcγCD with chemically cross-linked IG based on poly(ethyl acrylate) showed low σ values (0.54, 0.50, and 1.6 mS/cm, respectively), the σ value of the supramolecular polymeric IG based on poly(ethyl acrylate) reached 8 mS/cm, which is comparable to that of EMIm TFSI (9 mS/cm). These results indicated that the host−guest interaction in the supramolecular polymeric IG increases the σ value.

1. INTRODUCTION In recent years, ionic liquid gels (IGs),1,2 which were obtained by swelling the polymeric materials in an ionic liquid, have received much attention due to their high ionic conductivity (σ) and wide range of applications, such as solid electrolytes,3−8 capacitors,9,10 dye-sensitized solar cells,11−13 actuators,14,15 membranes,16,17 smart materials,18 and electrochemical devices.19,20 These functions are basically produced by physicochemical properties of ionic liquids as molten salts.21−23 Although the low glass-transition temperature and low melting point of ionic liquids as electrolyte salts preserve high σ values and electrochemical stability in polymeric materials,24,25 there were few reports about the physicochemical properties of IGs based on the design of polymer networks.26,27 The polymer backbone in IGs is classified in covalently bonded polymers with chemically cross-links,28−30 or not5,31 whereas nonchemically cross-linked polymers in IGs have not been brought to attention for material design because noncovalent interactions (cation−anion, cation−π, π−π, etc.) are inhibited by the cationic−anionic substituents of ionic liquids. Previously, Yan et al.32 and Zheng et al.33 reported supramolecular IGs using the host−guest interaction between cyclodextrin (CD) and ionic liquid. The host−guest interaction of CD and ionic liquid itself did not show gelation, and low-molecular-weight gelators were needed to form the © XXXX American Chemical Society

gel. Herein, we chose host−guest interactions of CD with adamantyl (Ad) derivatives as nonchemically cross-linked interactions to obtain supramolecular polymeric IGs. The host−guest interactions in this report take part as the crosslinking point, where, without gelators, the supramolecular polymeric IGs can be formed. The host−guest interactions have been widely used in applications as binders for lithium ion batteries,34 sensors,35 and polymeric materials.36−38 The advantages of the host−guest interaction in supramolecular polymeric IGs are its higher swelling property and lower Young’s modulus. The soft and flexible polymer network will further show high σ values and electrochemical stability as well as high fracture energy. Herein, we report the supramolecular polymeric IG based on CD and Ad [PAcγCD-Ad-R IG(x,y)] (Figure 1). The supramolecular polymeric IG containing CD and Ad was prepared by immersing the supramolecular elastomer in an ionic liquid. 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIm TFSI) was used as the ionic liquid because it has the highest σ value among other hydrophobic ionic liquids available.2,39,40 As reference IGs, Received: November 8, 2018 Revised: March 21, 2019

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Figure 1. (a−c) Chemical structures of (a) peracetylated 6-acrylamido methylether-γCD monomer (PAcγCD) as a host monomer, (b) 1-ethyl-3methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIm TFSI) as an ionic liquid, and (c) supramolecular ionic liquid gel (PAcγCD-Ad-R IG), chemically cross-linked ionic liquid gel (R IG), ionic liquid gel with PAcγCD (PAcγCD-R IG), and ionic liquid gel with Ad (Ad-R IG). (d) Group of main chain monomers (R): ethyl acrylate (EA) and butyl acrylate (BA). x, y, and z indicate the mole percent of PAcγCD, Ad, and 1,4butanediol diacrylate (BDA) units, respectively.

Figure 2. (a) Preparation of the PAcγCD-Ad-R elastomer(x,y) by bulk polymerization. (b) Preparation of the PAcγCD-Ad-R IG(x,y) by immersing the PAcγCD-Ad-R elastomer in the EMIm TFSI. x and y indicate the mole percent of PAcγCD and Ad units, respectively.

(Figure 2a and Tables S1 and S2). The PAcγCD-Ad-R IG was obtained by immersing the PAcγCD-Ad-R elastomer in EMIm TFSI (Schemes S2 and S3 and Figures S4−S8; Figure 2b). The reference samples, such as R IG, PAcγCD-R IG, and Ad-R IG (Figure 1c), were prepared by similar methods as described above using 1,4-butanediol diacrylate (BDA) as a chemical cross-linker (Tables S3−S8). The composition ratios of monomers in IGs are indicated by x, y, and z [PAcγCD-Ad-R IG(x,y), R IG(z), PAcγCD-R IG(x,0.1), and Ad-R IG(y,0.1)], which represent the mole percent of PAcγCD, Ad, and BDA units, respectively. The notation 0.1 at PAcγCD-R IG(x,0.1) and Ad-R IG(y,0.1) indicates 0.1 mol % BDA units. Solid-state 1H field gradient magic-angle spinning (FGMAS) NMR measurements were carried out to demonstrate the amount of PAcγCD and Ad unit ratio in the PAcγCD-Ad-R elastomer and PAcγCD-Ad-R IG according to a predefined ratio (Figures S9−S12). To confirm that the host−guest complexes take part as a cross-linking point, we prepared the

chemically cross-linked IGs, R IG, PAcγCD-R IG, and Ad-R IG were prepared to compare the σ value and fracture energy of PAcγCD-Ad-R IG and other chemically cross-linked IGs. The results show that not only the σ value but also the fracture energy of PAcγCD-Ad-R IGs are higher than those of the chemically cross-linked IGs.

2. RESULTS AND DISCUSSION 2.1. Preparation of Supramolecular Ionic Liquid Gels. Figure 2 shows the synthetic procedure of the PAcγCD-Ad-R IG(x,y). Before bulk radical copolymerization, the 2-ethyl-2adamantyl acrylate monomer (Ad) as a guest monomer was mixed and sonicated in acrylate monomers (EA, ethyl acrylate; BA, butyl acrylate) containing the peracetylated 6-monoacrylamide-methyl ether-modified monomer (PAcγCD; Scheme S1 and Figures S1−S3) as a host monomer to form inclusion complexes (Figure 2a). Polymerization was then carried out using 1-hydroxycyclohexyl phenyl ketone (IRGACURE 184) as a photo-induced radical initiator, successfully giving a supramolecular elastomer (PAcγCD-Ad-R elastomer) B

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Figure 3. (a) Swelling ratio of R elastomer(1), Ad-R elastomer(1,0.1), PAcγCD-R elastomer(1,0.1), and PAcγCD-Ad-R elastomer(1,1). (b) Young’s modulus of R IG(1), Ad-R IG(1,0.1), PAcγCD-R IG(1,0.1), and PAcγCD-Ad-R IG(1,1). R indicates the acrylate main chain polymer. Red, ethyl acrylate (EA); green, butyl acrylate (BA). R elastomer(1) and IG(1) are the chemically cross-linked elastomer and IG, respectively. Ad-R elastomer(1,0.1) and IG(1,0.1) are the guest elastomer and IG with a 0.1 mol % chemical cross-linker. PAcγCD-R elastomer(1,0.1) and IG(1,0.1) indicate the host elastomer and IG with a 0.1 mol % chemical cross-linker. PAcγCD-Ad-R elastomer(1,1) and IG(1,1) are the supramolecular elastomer and IG, respectively.

Figure 4. (a) Illustration of the instrument for ionic conductivity measurement. (b) Ionic conductivity of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIm TFSI) as the native ionic liquid and IGs [R IG(1), Ad-R IG(1,0.1), PAcγCD-R IG(1,0.1), and PAcγCDAd-R IG(1,1)]. R indicates the acrylate main chain polymer. Red, ethyl acrylate (EA); green, butyl acrylate (BA). (c) Conductivity of poly(ethyl acrylate)-based IGs with similar ionic liquid content [EA IG(0.5), Ad-EA IG(0.5,0.1), PAcγCD-EA IG(0.5,0.1), and PAcγCD-Ad-EA IG(0.5,0.5)]. R IG(z), Ad-R IG(y,0.1), PAcγCD-R IG(x,0.1), and PAcγCD-Ad-R IG(x,y) are the chemically cross-linked, guest, host, and supramolecular polymeric IG, respectively. Ad-R IG(y,0.1) and PAcγCD-R IG(x,0.1) are cross-linked with a 0.1 mol % chemical cross-linker.

higher than those of the elastomers based on poly(BA) because poly(EA) is more compatible in EMIm TFSI. The swelling ratio of the PAcγCD-Ad-EA elastomer(1,1) with 1 mol % CD and Ad units was larger than that of the EA elastomer(1), which had a 1 mol % chemical cross-linker. In addition, the swelling ratio of the PAcγCD-Ad-EA elastomer(1,1) was higher than those of the PAcγCD-EA elastomer(1,0.1) and the Ad-EA elastomer(1,0.1), even though the concentration of the cross-linking unit was 10 times higher. The swelling ratio is closely correlated with the ionic liquid content in the elastomer; a larger swelling ratio indicates a higher ionic liquid content (Figure S14). The cross-linking points of the host−guest interaction in the PAcγCD-Ad-EA elastomer(1,1) were relaxed during immersion in EMIm TFSI.

PAcγCD-Ad-R IG in 0.5−2 mol % and determined the Young’s modulus (Figure S13). 2.2. Swelling Ratio of Ionic Liquid Gels. We investigate the swelling ratio of the elastomers (PAcγCD-Ad-R, PAcγCDR, Ad-R, and R) immersed in EMIm TFSI for 24 h, which were determined by the following equation swelling ratio of elastomer =

WIG − Welastomer × 100% Welastomer

where Welastomer is the weight of elastomers (before immersion in an ionic liquid) and WIG is the weight of IGs (after elastomer immersed in EMIm TFSI). Figure 3a shows the swelling ratio of the elastomers. The swelling ratios of the elastomers based on poly(EA) were C

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Figure 5. (a) Self-diffusion coefficient of EMIm constituent from EMIm TFSI as the native ionic liquid and IGs [R IG(1), Ad-R IG(1,0.1), PAcγCD-R IG(1,0.1), and PAcγCD-Ad-R IG(1,1)]. R indicates the acrylate main chain polymer. Blue, EMIm TFSI; red, ethyl acrylate (EA); green, butyl acrylate (BA). R IG(1), Ad-R IG(1,0.1), PAcγCD-R IG(1,0.1), and PAcγCD-Ad-R IG(1,1) are the chemically cross-linked, guest, host, and supramolecular polymeric IG, respectively. Ad-R IG(1,0.1) and PAcγCD-R IG(1,0.1) are cross-linked with a 0.1 mol % chemical cross-linker. (b) Schematic illustration for the ionic liquid constituent mobility in IGs.

To understand the differences of swelling ratio between the elastomers, we investigated the Young’s modulus of the IGs. The Young’s modulus of materials is correlated to the crosslinking density of materials, which means that the sample with a low cross-linking density shows a high swelling ratio. The Young’s modulus of EA IG(1,1) was higher than those of AdEA IG(1,0.1) and PAcγCD-EA IG(1,0.1), because the concentration of the cross-linking unit was 10 times higher. The Young’s modulus of the PAcγCD-Ad-EA IG(1,1) was lower than those of not only EA IG(1,1) but also Ad-EA IG(1,0.1) and PAcγCD-EA IG(1,0.1) because the interactions of CD and Ad units are flexible and reversible. These results indicate that the cross-linking density of PAcγCD-Ad-EA IG(1,1) was lower than that of the chemically cross-linked IG. The flexible and reversible nonchemical cross-linkers of PAcγCD-Ad-R IGs produced high swelling properties. 2.3. Conductivity of Ionic Liquid Gels. Figure 4a shows the ionic conductive measurement system with a computercontrolled Hewlett-Packard 4284A Precision LCR (inductance (L), capacitance (C), and resistance (R)) meter with a frequency of 20 Hz to 1 MHz. The measurement temperature was set constant at 25 °C. The calculation procedure to obtain the σ value is described in the Supporting Information (Figure S15). Figure 4b shows the σ values of EMIm TFSI as the native ionic liquid and IGs. The σ value of EMIm TFSI without polymers was 9.0 mS/cm. The σ values of IGs based on poly(EA) were higher than those of IGs based on poly(BA). The σ value of poly(EA)- or poly(BA)-based IGs was lower than that of EMIm TFSI because of the dispersion of EMIm TFSI was suppressed in the polymer networks. The dispersion properties of EMIm TFSI will be discussed later in Section 2.4 using a self-diffusion coefficient. The σ value of the PAcγCD-Ad-EA IG(1,1) (8.0 mS/cm) was higher than those of the EA IG(1) (0.54 mS/cm), Ad-EA IG(1,0.1) (0.50 mS/cm), and PAcγCD-EA IG(1,0.1) (1.6 mS/ cm). The σ value of PAcγCD-Ad-EA IG(1,1) (8.0 mS/cm) showed a similar result with EMIm TFSI (9.0 mS/cm). These results showed that the host−guest interaction raises the σ value of IGs. Although the σ values of poly(BA)-based IGs

were low, the trend was similar to poly(EA)-based IGs (Figure 4b). The σ value of IGs slightly depended on the molar ratio of cross-linkers (0.5−2 mol %); however, it did not make any significant difference on the σ value (Figure S16). Figure 4c compares the σ values of the similar ionic liquid content of poly(EA)-based IGs. The σ value of the PAcγCDAd-EA IG(0.5,0.5) (8.0 mS/cm) was 13 times higher than that of the EA IG(0.5) (0.61 mS/cm). The σ value of the PAcγCDAd-EA IG(0.5,0.5) was also 13 and 4 times higher than those of Ad-EA IG(0.5,0.1) and PAcγCD- EA IG(0.5,0.1), respectively. Therefore, the host−guest interactions working as a cross-linking point in supramolecular polymeric IGs are an effective network structure to increase the σ value. 2.4. Self-Diffusion Coefficient of Ionic Liquid Gels. The σ value is related to the mobility of ionic liquid. The faster mobility of ionic liquid will show the higher σ value in the IGs. To understand the mobility of an ionic liquid constituent, the self-diffusion coefficient (D) of EMIm TFSI was determined from diffusion-ordered spectroscopy (DOSY) NMR (Figures S17−S25). In this regard, the diffusion of the TFSI substituent was slower than that of the EMIm substituent;2 therefore, we focus on the D value of the EMIm substituent to determine the ionic liquid constituent mobility. Figure 5a shows the D value of the EMIm substituent in the IGs. The D value of poly(EA)-based IGs (Figures S18−S21) was faster than that of the poly(BA)-based IGs (Figures S22− S25) because poly(EA)-based IGs have a shorter side chain compared with poly(BA)-based IGs. The D value of PAcγCDAd-EA IG(1,1) (2.30 × 10−9 cm2/s, Figure S18) was faster than that of the EA IG(1) (7.99 × 10−10 cm2/s, Figure S19), Ad-EA IG(1,0.1) (2.49 × 10−10 cm2/s, Figure S20), or PAcγCD-EA IG(1,0.1) (1.09 × 10−9 cm2/s, Figure S21). The D value of the PAcγCD-Ad-EA IG(1,1) (2.30 × 10−9 cm2/s) showed a similar result with EMIm TFSI (2.83 × 10−9 cm2/s, Figure S17). These results showed that the host−guest interaction raises the mobility of ionic liquid. The σ value of IGs is in agreement with the D value from the EMIm TFSI constituent. The EMIm substituent in the PAcγCD-Ad-R IG showed the fastest D value compared with the EMIm substituent in chemically cross-linked IGs. Figure D

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Figure 6. (a, b) Relationship between Young’s modulus and ionic conductivity for (a) poly(EA)-based IGs and (b) poly(BA)-based IGs. (c, d) Relationship between fracture energy with ionic conductivity for (c) poly(EA)-based IGs and (d) poly(BA)-based IGs [square, R IG(z); circle, AdR IG(y,0.1); triangle, PAcγCD-R IG(x,0.1); diamond, PAcγCD-Ad-R IG(x,y); black, 0.5 mol %; blue, 1 mol %; red, 2 mol %].

PAcγCD-Ad-EA IG; however, the σ value of PAcγCD-Ad-BA IG was lower than that of PAcγCD-Ad-EA IG due to the inhibition of EMIm TFSI mobility. On the basis of these findings, we successfully prepared a greater fracture energy IG with the low cross-linking density by using the host−guest interaction that still showed high σ values.

5b shows the schematic illustration of the ionic liquid constituent mobility in the IGs. The ionic liquid constituent is almost static in R IGs, whereas the ionic liquid constituent shows high mobility in the PAcγCD-Ad-R IGs. The mesh size of supramolecular polymeric IGs is larger than those of chemically cross-linked IGs because the cross-linking density of the supramolecular polymeric IGs is lower than those of chemically cross-linked IGs due to the flexibility and reversibility of the host−guest cross-linking point. Therefore, the ionic mobility in supramolecular polymeric ionic liquid gels is faster than those in cross-linked ionic liquid gels. 2.5. Relationship between Young’s Modulus or Fracture Energy and Conductivity. Panzer and Visentin41 reported the relationship between Young’s modulus and σ by using poly(ethylene glycol) diacrylate with EMIm TFSI. They demonstrated that conductive materials with low Young’s modulus should have high σ values. Although lower Young’s modulus materials with less than 50 kPa are expected to realize high σ values, these materials were soft and brittle due to low fracture energy. Supramolecular polymeric IGs (PAcγCD-Ad-R IGs) with lower Young’s modulus will be compatible with high σ values and high fracture energy. Therefore, we investigate the relationship between Young’s modulus or fracture energy and σ. Figure 6a,b shows the relationship between Young’s modulus and σ of IGs. The σ value of PAcγCD-Ad-R IG with low Young’s modulus was higher than those of R IG, AdR IG, and PAcγCD-R IG. Figure 6c,d shows the relationship between fracture energy and σ of IGs. The PAcγCD-Ad-R IG showed higher fracture energy than R IG, Ad-R IG, and PAcγCD-R IG in the case of the same molar ratio. The fracture energy of PAcγCD-Ad-BA IG was higher than that of

3. CONCLUSIONS Supramolecular polymeric IGs were successfully prepared from immersion of the host−guest elastomer containing PAcγCD and Ad in EMIm TFSI. The PAcγCD-Ad-R elastomer showed a larger swelling ratio among the other chemically cross-linked elastomers because EMIm TFSI was easier to penetrate the PAcγCD-Ad-R elastomer than the chemically cross-linked elastomers due to relaxation of the host−guest cross-linking point in the PAcγCD-Ad-R elastomer by immersion in EMIm TFSI. Therefore, the Young’s modulus of the PAcγCD-Ad-R IGs was lower than those of the chemically cross-linked IGs, indicating that the cross-linking density of the PAcγCD-Ad-R IGs was the lowest. The σ value of IGs is in agreement with the D value of the EMIm substituent from EMIm TFSI in the IGs. The PAcγCD-Ad-R IG showed higher σ and D values of the EMIm substituent in the PAcγCD-Ad-R IG compared with chemically cross-linked IGs because of the low Young’s modulus. The σ and D values of the PAcγCD-Ad-EA IG were almost similar to EMIm TFSI as the native ionic liquid. The fracture energy of the PAcγCD-Ad-R IG with low Young’s modulus was higher than those of chemically cross-linked IGs. Although low Young’s modulus materials were soft and brittle due to low fracture energy in general, the fracture energy of the PAcγCD-Ad-R IG with low Young’s modulus was higher than those of the chemically cross-linked IGs. We concluded that E

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(7) Le Bideau, J.; Ducros, J.-B.; Soudan, P.; Guyomard, D. SolidState Electrode Materials with Ionic-Liquid Properties for Energy Storage: the Lithium Solid-State Ionic-Liquid Concept. Adv. Funct. Mater. 2011, 21, 4073−4078. (8) Wang, S.; Hsia, B.; Carraro, C.; Maboudian, R. Highperformance all solid-state micro-supercapacitor based on patterned photoresist-derived porous carbon electrodes and an ionogel electrolyte. J. Mater. Chem. A 2014, 2, 7997−8002. (9) Lewandowski, A.; Zajder, M.; Frąckowiak, E.; Beguin, F. Supercapacitor based on activated carbon and polyethylene oxideKOH-H2O polymer electrolyte. Electrochim. Acta 2001, 46, 2777− 2780. (10) Sato, T.; Masuda, G.; Takagi, K. Electrochemical properties of novel ionic liquids for electric double layer capacitor applications. Electrochim. Acta 2004, 49, 3603−3611. (11) Li, B.; Wang, L.; Kang, B.; Wang, P.; Qiu, Y. Review of recent progress in solid-state dye-sensitized solar cells. Sol. Energy Mater. Sol. Cells 2006, 90, 549−573. (12) Snaith, H. J.; Schmidt-Mende, L. Advances in liquid-electrolyte and solid-state dye-sensitized solar cells. Adv. Mater. 2007, 19, 3187− 3200. (13) Yang, H.; Huang, M.; Wu, J.; Lan, Z.; Hao, S.; Lin, J. The polymer gel electrolyte based on poly(methyl methacrylate) and its application in quasi-solid-state dye-sensitized solar cells. Mater. Chem. Phys. 2008, 110, 38−42. (14) Ding, J.; Zhou, D.; Spinks, G.; Wallace, G.; Forsyth, S.; Forsyth, M.; MacFarlane, D. Use of ionic liquids as electrolytes in electromechanical actuator systems based on inherently conducting polymers. Chem. Mater. 2003, 15, 2392−2398. (15) Imaizumi, S.; Kokubo, H.; Watanabe, M. Polymer Actuators Using Ion-Gel Electrolytes Prepared by Self-Assembly of ABATriblock Copolymers. Macromolecules 2012, 45, 401−409. (16) Gin, D. L.; Noble, R. D. Designing the Next Generation of Chemical Separation Membranes. Science 2011, 332, 674−676. (17) Hoarfrost, M. L.; Segalman, R. A. Ionic Conductivity of Nanostructured Block Copolymer/Ionic Liquid Membranes. Macromolecules 2011, 44, 5281−5288. (18) Mecerreyes, D. Polymeric ionic liquids: Broadening the properties and applications of polyelectrolytes. Prog. Polym. Sci. 2011, 36, 1629−1648. (19) Lu, J.; Yan, F.; Texter, J. Advanced applications of ionic liquids in polymer science. Prog. Polym. Sci. 2009, 34, 431−448. (20) Ye, Y.-S.; Rick, J.; Hwang, B.-J. Ionic liquid polymer electrolytes. J. Mater. Chem. A 2013, 1, 2719−2743. (21) Rogers, R. D.; Seddon, K. R. Ionic Liquids–Solvents of the Future? Science 2003, 302, 792−793. (22) Welton, T. Room-temperature ionic liquids. Solvents for synthesis and catalysis. Chem. Rev. 1999, 99, 2071−2084. (23) Wilkes, J. S.; Zaworotko, M. J. Air and Water Stable 1-Ethyl-3Methylimidazolium Based Ionic Liquids. J. Chem. Soc., Chem. Commun. 1992, 0, 965−967. (24) Angell, C. A.; Liu, C.; Sanchez, E. Rubbery Solid Electrolytes with Dominant Cationic Transport and High Ambient Conductivity. Nature 1993, 362, 137−139. (25) Watanabe, M.; Yamada, S.-I.; Sanui, K.; Ogata, N. High ionic conductivity of new polymer electrolytes consisting of polypyridinium, pyridinium and aluminium chloride. J. Chem. Soc., Chem. Commun. 1993, 0, 929−931. (26) Ohno, H.; Ito, K. Room-temperature molten salt polymers as a matrix for fast ion conduction. Chem. Lett. 1998, 27, 751−752. (27) Yuan, J.; Antonietti, M. Poly(ionic liquid)s: Polymers expanding classical property profiles. Polymer 2011, 52, 1469−1482. (28) Kamio, E.; Yasui, T.; Iida, Y.; Gong, J. P.; Matsuyama, H. Inorganic/Organic Double-Network Gels Containing Ionic Liquids. Adv. Mater. 2017, 29, 1704118. (29) Obadia, M. M.; Mudraboyina, B. P.; Serghei, A.; Montarnal, D.; Drockenmuller, E. Reprocessing and Recycling of Highly CrossLinked Ion-Conducting Networks through Transalkylation Exchanges of C-N Bonds. J. Am. Chem. Soc. 2015, 137, 6078−6083.

the host−guest interaction at supramolecular polymeric IGs is an important part to prepare low cross-linking density materials with high σ values and high fracture energy. This supramolecular polymeric IGs based on the host−guest interaction are expected to be applied as electrochemical materials (minimum σ value required is equal or over 0.1 mS/ cm42) in the future.

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.macromol.8b02395. Experimental details, measurements, preparation and characterization of peracetylated 6-acrylamido methylether-γCD (PAcγCD), ionic liquid (EMIm TFSI) and elastomers, and characterization of ionic liquid gels (IGs) (PDF)

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AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected] (Y.T.). *E-mail: [email protected] (A.H.). *E-mail: [email protected] (H.Y.). ORCID

Garry Sinawang: 0000-0002-2248-0485 Yuichiro Kobayashi: 0000-0002-9967-5520 Yongtai Zheng: 0000-0001-8906-8412 Yoshinori Takashima: 0000-0002-2620-3266 Akira Harada: 0000-0002-9309-5939 Hiroyasu Yamaguchi: 0000-0002-4801-5071 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This research was funded by the Grants-in-Aid for Scientific Research (B) (JP18H02035, JP17H03115, and JP17H03416) from MEXT, Japan and the Mazda Foundation. We wish to thank Prof. T. Inoue and Dr. O. Urakawa of Osaka University for access to conductivity measurements. We also wish to acknowledge the NMR technical assistance of Dr. N. Inazumi.

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REFERENCES

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DOI: 10.1021/acs.macromol.8b02395 Macromolecules XXXX, XXX, XXX−XXX