Subscriber access provided by Caltech Library Services
Communication
Zwitterion-Containing Ionogel Electrolytes Fatin Lind, Luis Rebollar, Prity Bengani-Lutz, Ayse Asatekin, and Matthew J Panzer Chem. Mater., Just Accepted Manuscript • DOI: 10.1021/acs.chemmater.6b04456 • Publication Date (Web): 29 Nov 2016 Downloaded from http://pubs.acs.org on November 30, 2016
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
Chemistry of Materials is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 6
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Chemistry of Materials
Zwitterion-Containing Ionogel Electrolytes Fatin Lind, Luis Rebollar, Prity Bengani-Lutz, Ayse Asatekin, and Matthew J. Panzer* Department of Chemical & Biological Engineering, Tufts University, 4 Colby St., Medford, MA 02155, USA ABSTRACT: Nonvolatile, solid electrolytes represent an important component of future electrochemical energy storage devices possessing enhanced safety attributes. Here, zwitterionic (ZI) sulfobetaine functional groups have been incorporated into polymersupported ionic liquid gel composites, known as ionogels. Zwitterion-containing ionogels are found to exhibit high room temperature ionic conductivity (6.5 mS cm-1) and tunable compressive elastic modulus values (4.1 kPa to 900 kPa), while retaining the outstanding thermal and electrochemical stability of the ionic liquid component, 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide. Covalently attaching the ZI moieties to the polymer scaffold promotes enhanced ionogel homogeneity over time, compared to the use of a ZI additive that is free to diffuse and aggregate within the gel. Evidence of zwitterion self-interactions (dipole-dipole) and zwitterion-ionic liquid interactions (ion-dipole) that promote polymer physical cross-link formation and ionic liquid cation/anion pair dissociation, respectively, has been obtained. This demonstration of ZI copolymersupported ionogels will open up new avenues of inquiry aimed toward understanding the largely unexplored realm of zwitterion/ionic liquid systems.
Ionic liquids, which are molten salts at or near room temperature,1-3 have now been firmly established as a remarkable class of ultralow volatility, next-generation fluids for a variety of applications, including: materials synthesis, catalysis, gas separations, and electrochemical energy storage, to name a few.4-6 Their ion-dense character suggests that ionic liquids may be particularly well-suited to serve as electrolytes that can impart enhanced safety (i.e. nonvolatility, nonflammability7) to future electrochemical devices, including batteries and supercapacitors.8,9 A further gain in electrolyte safety is expected to result from immobilization of the ionic liquid in a leakproof gel form;10 in several manifestations, a cross-linked polymer scaffold has been employed to create what is termed an ionogel (or ion gel).11,12 An ability to tune the flexibility of ionogel electrolytes is highly desirable for many anticipated applications of these materials. As one would expect, ionogel elastic modulus can be increased by introducing additional cross-links within the supporting polymer scaffold.12 However, this usually comes at the cost of reduced ionic conductivity.13-15 Zwitterionic (ZI) molecules contain an equal number of positive and negative charged groups, and can exhibit large molecular dipole moments (e.g. 19–28 D).16 ZI additives have previously been shown to enhance the degree of lithium salt dissociation within ionic liquids and other electrolyte systems,17-19 likely due to significant ion-dipole interactions.20 Moreover, ZI copolymers, having ZI functional groups covalently tethered to the polymer backbone, are known to demonstrate self-associating behavior in aqueous environments21,22 that can be leveraged, for example, to improve the mechanical integrity of hydrogels through the formation of interchain ZI dipole-dipole physical cross-links23,24 or to finely tune the ionic channel domain size of membrane selective layers.25 Although the properties of ZI copolymer/ionic liquid mixtures have not been widely studied, the swelling of a ZI copolymer
with a water-miscible ionic liquid has been reported.26 Inspired by these works and the unique attributes of ZI materials, this work sought to examine the potential for ZI copolymersupported ionogels to simultaneously exhibit high room temperature ionic conductivities and tunable elastic moduli, due to the ion-dissociating and self-associating properties of ZI materials, respectively. In this Communication, we demonstrate that ZI copolymer-supported ionogels can be readily fabricated via in situ UV-initiated free radical polymerization,27,28 and that they indeed display high, nearly constant room temperature ionic conductivities, even as gel compressive elastic modulus values are increased more than 200-fold by varying the ZI content. Ionogel electrolytes were prepared using the aprotic ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI TFSI, Fig. 1a) due to its high room temperature ionic conductivity (approximately 10 mS cm-1) and wide electrochemical stability window (4.2 V),29 which are important for electrical energy storage devices. The ZI monomer, sulfobetaine vinylimidazole (SBVI, Fig. 1b), was selected due to its imidazolium moiety (common to the EMI+ cation), in an attempt to promote better compatibility with the ionic liquid. Since the large dipole moments of ZI molecules typically render them strongly self-associating and hydrophilic,30,31 one could reasonably expect to encounter a challenge dissolving zwitterions into a hydrophobic, waterimmiscible ionic liquid (such as EMI TFSI). Indeed, we observed extremely low/sparing solubility of several ZI monomers, including SBVI, in neat EMI TFSI. However, it was found that the compatibility of SBVI with the ionic liquid could be substantially improved through the addition of 2,2,2trifluoroethyl methacrylate (TFEMA), which played the dual role here of cosolvent/comonomer in preparing homogeneous ionogel precursor solutions; it should be noted that 2,2,2trifluoroethanol is routinely used as a good solvent for ZI co-
1 ACS Paragon Plus Environment
Chemistry of Materials
The increase in SBMI gel elastic modulus with greater ZI content, therefore, can be explained by the unintended creation of SBMI particles that act as nanofillers.33 In contrast, the SBVI gels maintained their transparent and homogeneous appearance (Fig. 2c) because the ZI functional groups were covalently bonded to the polymer scaffold.
a 10
Elastic Modulus (kPa)
polymers.25,32 By varying the SBVI/TFEMA molar ratio in ionogel precursor solutions that contained a fixed amount of EMI TFSI (80 ± 1 mol%, 76 ± 1 vol.%), ZI contents as high as 7 mol% could be realized; ionogel synthesis and electrical characterization were performed under strictly O2/H2O-free conditions (see Supporting Information, SI). In order to examine potential differences in the properties of ionogels having a ZI component covalently tethered to the polymer scaffold versus simply present within the gel as an additive, a nonpolymerizable ZI analogue to SBVI, sulfobetaine methylimidazole (SBMI, Fig. 1c), was also used to prepare ionogels. Both SBVI- and SBMI-containing ionogels included TFEMA, as well as a small amount of pentaerythritol tetraacrylate (PETA4) as a covalent cross-linker;28 photographs of representative free-standing zwitterion-containing ionogel samples are displayed in Figures 1d and 1e.
10
10
10
3
SBVI Gels SBMI Gels Non ZI Gel 2
1
0
0
b 1
Compressive elastic modulus and room temperature ionic conductivity values for the two types of zwitterion-containing ionogels, possessing varying ZI contents for a fixed ionic liquid volume fraction (76 ± 1 vol.%), are shown in Figures 2a and 2b; for comparison, the properties of a non-ZI ionogel that contained only TFEMA/PETA-4 in the precursor solution are also displayed. It is important to note that the same quantity of PETA-4 (1.5 ± 1 mol%) was employed in each ionogel formulation. As seen in Fig. 2a, increasing the ZI content incorporated within the polymer scaffold (i.e. SBVI gels) within a range of 1–7 mol% resulted in a dramatic increase in ionogel elastic modulus values (4.1 kPa to 900 kPa) that is attributed to the spontaneous formation of ZI dipole-dipole physical cross-links between copolymer chains. While this phenomenon has been reported to occur in hydrogels,23,24 the present results clearly demonstrate that ZI copolymers can self-associate within a hydrophobic ionic liquid such as EMI TFSI, as well. By comparison, the elastic modulus values of SBMI-containing ionogels, for which the ZI component was not covalently incorporated into the polymer scaffold, increased only slightly (10 kPa to 20 kPa) with increasing ZI content (2.5–7 mol%). Due to its ability to diffuse freely within the ionogel, SBMI tended to self-associate into visible colloidal aggregates within a day or two following gel formation, as seen in Fig. 2c.
4
6
8
11 SBVI Gels SBMI Gels Non ZI Gel EMI TFSI
10 9 8 7 6 5 4 3 0
Figure 1. Molecular structures of: (a) ionic liquid, EMI TFSI, (b) zwitterionic (ZI) monomer, SBVI, and (c) non-polymerizable ZI additive, SBMI. Panels (d) and (e): photographs of freestanding SBVI- (5 mol%) and SBMI- (1 mol%) containing ionogels, respectively. Both ionogels are cylindrical, with a diameter/height of 6.7 mm/3.3 mm.
2
Zwitterion Content (mol %) Ionic Conductivity (mS cm )
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 2 of 6
2
4
6
8
Zwitterion Content (mol %)
c
0h
48 h
SBVI Gel
SBMI Gel
Figure 2. (a) Compressive elastic modulus and (b) room temperature ionic conductivity values of zwitterion-containing and non-ZI ionogel electrolytes; all ionogel samples contained 76 ± 1 vol.% ionic liquid (EMI TFSI). (c) Photographs of SBVI-containing ionogel (top) and SBMI-containing ionogel (bottom) samples inverted in a small glass vial, taken immediately after gel formation (0 h) and after 48 h.
The room temperature ionic conductivity values shown in Fig. 2b reveal a remarkable feature of these zwitterioncontaining ionogels: gel ionic conductivity (approximately 6.5 ± 1 mS cm-1) is essentially independent of ZI content over the range of compositions examined (0-7 mol%), even as gel elastic modulus values increase by orders of magnitude over the same range. Ionogel conductivity values were lower than that of the neat ionic liquid (10.2 mS cm-1) due to the presence of the polymer scaffold, which both reduces the ionic liquid concentration and impedes ionic motion. However, the fact that
2 ACS Paragon Plus Environment
Page 3 of 6
SBVI gel elastic modulus values could be increased more than 200-fold while maintaining an undiminished level of ionic conductivity represents a significant departure from previously-studied ionogel systems. Typically, such a dramatic increase in gel compressive elastic modulus is accompanied by a substantial decrease in ionic conductivity due to the presence of additional polymeric scaffold material/cross-links.12 Thus, the invariance of the ionic conductivity values obtained for these zwitterion-containing ionogels provides evidence that ZI functional groups may also serve to effectively dissociate additional cation/anion pairs or clusters in the ionic liquid34,35 via ion-dipole interactions. Further evidence of enhanced EMI TFSI ion pair dissociation can be seen in Figure 3, which shows the room temperature ionic conductivity values of several zwitterion-containing ionogel precursor solutions (prior to gelation), along with those of their corresponding ionogels (i.e., post-UV curing). All of the SBVI- and SBMI-containing ionogel precursor solutions exhibited higher ionic conductivities relative to their gelled forms due to the lack of a solid polymer scaffold that hinders ionic motion. Notably, the SBVI-containing precursor solutions displayed ionic conductivity values nearly equal to that of the neat ionic liquid, despite the fact that they contained only 76 vol.% ionic liquid. This observation clearly demonstrates the ability of the ZI functional groups to augment the degree of cation/anion pair dissociation relative to the level exhibited by neat EMI TFSI. A similar effect was observed for the non-ZI precursor solution, suggesting that TFEMA may also assist with ion pair dissociation.28 It is likely that the SBMI-containing precursor solutions displayed lower ionic conductivity compared to the SBVI solutions due to a greater degree of ZI self-association in the case of SBMI, which would reduce the effective number of zwitterion-ion interactions.
Figure 3. Room temperature ionic conductivity values of SBVIand SBMI-containing ionogel precursor solutions before gelation (open symbols), and for the corresponding ionogels after gelation (filled symbols). The dashed line indicates the ionic conductivity of the neat ionic liquid (EMI TFSI).
The schematic shown in Figure 4 illustrates our current understanding of the different types of cross-links and ZI interactions present within zwitterion-containing ionogels having ZI functional groups covalently bonded to the polymer scaffold. ZI groups augment the macroscopic stiffness of covalently cross-linked ionogel scaffolds through the formation of addi-
tional inter-/intrachain physical cross-links via Coulombic self-association of their charged portions; in addition, ZI groups can promote ionic liquid cation/anion dissociation (iondipole interaction) to enhance ionic conductivity by creating additional mobile charge carriers. Covalently tethering ZI functionality to the polymer backbone can prevent significant zwitterion aggregation within the gel (as seen in Fig. 2c), which promotes better ionogel homogeneity over time and facilitates a greater degree of zwitterion-ionic liquid interaction compared to the use of a non-tethered ZI additive. Importantly, the SBVI/TFEMA/PETA-4 copolymer scaffolds demonstrated here also do not significantly decrease the outstanding electrochemical and thermal stability of the ionic liquid, EMI TFSI (see SI).
ZI association (physical x-link)
− + covalent x-link
IL dissociation (ion-dipole)
+ − − + + −
+ EMI
TFSI−
+ −
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Chemistry of Materials
Figure 4. Schematic illustration of the two types of cross-links (xlinks) present in zwitterion-containing ionogels, as well as an attractive interaction (ion-dipole) between an ionic liquid ion and ZI functional group. These features serve to increase elastic modulus and promote high ionic conductivity in zwitterion-containing ionogel electrolytes, respectively.
In conclusion, zwitterion-containing ionogel electrolytes have been successfully synthesized via in situ UV-initiated free radical polymerization/cross-linking within an aprotic, hydrophobic ionic liquid, EMI TFSI. The solubility of the ZI monomer (SBVI) or ZI additive (SBMI) in the ionogel precursor solution was made possible through the use of a liquid comonomer (TFEMA). While both types of zwitterioncontaining ionogels created here (i.e., SBVI gels, with ZI groups covalently bonded to the polymer scaffold vs. freelydiffusing ZI additives, SBMI gels) displayed high room temperature ionic conductivities (≈6.5 mS cm-1), SBVI gels were found to exhibit better homogeneity over time and compressive elastic modulus values that could be tuned over two orders of magnitude by varying the ZI content, without suffering a loss in ionic conductivity. Within the ion-dense environment of the ionic liquid, ZI groups interact strongly with each other as well as with the ions of the ionic liquid, resulting in the formation of physical cross-links within the polymer scaffold and enhanced cation/anion dissociation, respectively. Therefore, zwitterion-containing ionogels represent an intriguing class of solid electrolyte materials that may offer new ways to effectively exploit the outstanding properties of ionic liquids for safer energy storage and other future applications.
ASSOCIATED CONTENT Supporting Information. The Supporting Information is available free of charge on the ACS Publications website. Experimental details and additional data (PDF).
3 ACS Paragon Plus Environment
Chemistry of Materials
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Corresponding Author *
[email protected] Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS M.J.P. thanks the NSF (ECCS-1201935), and A.A. thanks the NSF (CBET-1437772, CHE-1508049) and the Massachusetts Clean Energy Center for financial support.
REFERENCES (1) Huddleston, J. G.; Visser, A. E.; Reichert, W. M.; Willauer, H. D.; Broker, G. A.; Rogers, R. D. Characterization and Comparison of Hydrophilic and Hydrophobic Room Temperature Ionic Liquids Incorporating the Imidazolium Cation. Green Chem. 2001, 3, 156–164. (2) Rogers, R. D.; Seddon, K. R. Ionic Liquids--Solvents of the Future? Science 2003, 302, 792–793. (3) Krossing, I.; Slattery, J. M.; Daguenet, C.; Dyson, P. J.; Oleinikova, A.; Weingärtner, H. Why Are Ionic Liquids Liquid? A Simple Explanation Based on Lattice and Solvation Energies. J. Am. Chem. Soc. 2006, 128, 13427–13434. (4) Antonietti, M.; Kuang, D.; Smarsly, B.; Zhou, Y. Ionic Liquids for the Convenient Synthesis of Functional Nanoparticles and Other Inorganic Nanostructures. Angew. Chem. Int. Ed. 2004, 43, 4988– 4992. (5) Armand, M.; Endres, F.; MacFarlane, D. R.; Ohno, H.; Scrosati, B. Ionic-Liquid Materials for the Electrochemical Challenges of the Future. Nature Mater. 2009, 8, 621–629. (6) Gurkan, B. E.; la Fuente, de, J. C.; Mindrup, E. M.; Ficke, L. E.; Goodrich, B. F.; Price, E. A.; Schneider, W. F.; Brennecke, J. F. Equimolar CO2 Absorption by Anion-Functionalized Ionic Liquids. J. Am. Chem. Soc. 2010, 132, 2116–2117. (7) MacFarlane, D. R.; Tachikawa, N.; Forsyth, M.; Pringle, J. M.; Howlett, P. C.; Elliott, G. D.; Davis, J. H.; Watanabe, M.; Simon, P.; Angell, C. A. Energy Applications of Ionic Liquids. Energy Environ. Sci. 2014, 7, 232–250. (8) Lin, R.; Taberna, P.-L.; Fantini, S.; Presser, V.; Pérez, C. R.; Malbosc, F.; Rupesinghe, N. L.; Teo, K. B. K.; Gogotsi, Y.; Simon, P. Capacitive Energy Storage From −50 to 100 °C Using an Ionic Liquid Electrolyte. J. Phys. Chem. Lett. 2011, 2, 2396–2401. (9) Kim, G. T.; Jeong, S. S.; Xue, M. Z.; Balducci, A.; Winter, M.; Passerini, S.; Alessandrini, F.; Appetecchi, G. B. Development of Ionic Liquid-Based Lithium Battery Prototypes. J. Power Sources 2012, 199, 239–246. (10) Marr, P. C.; Marr, A. C. Ionic Liquid Gel Materials: Applications in Green and Sustainable Chemistry. Green Chem. 2015, 18, 105–128. (11) Gu, Y.; Zhang, S.; Martinetti, L.; Lee, K. H.; McIntosh, L. D.; Frisbie, C. D.; Lodge, T. P. High Toughness, High Conductivity Ion Gels by Sequential Triblock Copolymer Self-Assembly and Chemical Cross-Linking. J. Am. Chem. Soc. 2013, 135, 9652–9655. (12) Visentin, A. F.; Panzer, M. J. Poly(Ethylene Glycol) Diacrylate-Supported Ionogels with Consistent Capacitive Behavior and Tunable Elastic Response. ACS Appl. Mater. Interfaces 2012, 4, 2836–2839. (13) Visentin, A. F.; Alimena, S.; Panzer, M. J. Influence of Ionic Liquid Selection on the Properties of Poly(Ethylene Glycol) Diacrylate-Supported Ionogels as Solid Electrolytes. ChemElectroChem 2014, 1, 718–721. (14) Zhang, S.; Lee, K. H.; Sun, J.; Frisbie, C. D.; Lodge, T. P. Viscoelastic Properties, Ionic Conductivity, and Materials Design Considerations for Poly(Styrene- B-Ethylene Oxide- B-Styrene)Based Ion Gel Electrolytes. Macromolecules 2011, 44, 8981–8989. (15) Ueki, T.; Nakamura, Y.; Usui, R.; Kitazawa, Y.; So, S.; Lodge, T. P.; Watanabe, M. Photoreversible Gelation of a Triblock
Page 4 of 6
Copolymer in an Ionic Liquid. Angew. Chem. Int. Ed. 2015, 54, 3018–3022. (16) Galin, M.; Chapoton, A.; Galin, J.-C. Dielectric Increments, Intercharge Distances and Conformation of Quaternary Ammonioalkylsulfonates and Alkoxydicyanoethenolates in Aqueous and Tirfluoroethanol Solutions. J. Chem. Soc., Perkin Trans. 2 1993, 545–553. (17) Byrne, N.; Howlett, P. C.; MacFarlane, D. R.; Forsyth, M. The Zwitterion Effect in Ionic Liquids: Towards Practical Rechargeable Lithium-Metal Batteries. Adv. Mater. 2005, 17, 2497–2501. (18) Byrne, N.; Pringle, J. M.; Tiyapiboonchaiya, C.; MacFarlane, D. R.; Forsyth, M. The Additive Effect of Zwitterion and NanoParticles on Ion Dissociation in Polyelectrolytes. Electrochim. Acta 2005, 50, 2733–2738. (19) Yoshizawa, M.; Hirao, M.; Ito-Akita, K.; Ohno, H. Ion Conduction in Zwitterionic-Type Molten Salts and Their Polymers. J. Mater. Chem. 2001, 11, 1057–1062. (20) Shao, Q.; He, Y.; Jiang, S. Molecular Dynamics Simulation Study of Ion Interactions with Zwitterions. J. Phys. Chem. B 2011, 115, 8358–8363. (21) Vasantha, V. A.; Jana, S.; Parthiban, A.; Vancso, J. G. Water Swelling, Brine Soluble Imidazole Based Zwitterionic Polymers – Synthesis and Study of Reversible UCST Behaviour and Gel–Sol Transitions. Chem. Commun. 2014, 50, 46–48. (22) Jiménez, Z. A.; Yoshida, R. Temperature Driven SelfAssembly of a Zwitterionic Block Copolymer That Exhibits Triple Thermoresponsivity and pH Sensitivity. Macromolecules 2015, 48, 4599–4606. (23) Herrick, W. G.; Nguyen, T. V.; Sleiman, M.; McRae, S.; Emrick, T. S.; Peyton, S. R. PEG-Phosphorylcholine Hydrogels as Tunable and Versatile Platforms for Mechanobiology. Biomacromolecules 2013, 14, 2294–2304. (24) Peng, X.; Liu, H.; Yin, Q.; Wu, J.; Chen, P.; Zhang, G.; Xie, Y.; Liu, G.; Wu, C. A Zwitterionic Gel Electrolyte for Efficient SolidState Supercapacitors. Nat Comms 2016, 7, 11782. (25) Bengani, P.; Kou, Y.; Asatekin, A. Zwitterionic Copolymer Self-Assembly for Fouling Resistant, High Flux Membranes with Size-Based Small Molecule Selectivity. J. Membr. Sci. 2015, 493, 755–765. (26) Brown, R. H.; Duncan, A. J.; Choi, J.-H.; Park, J. K.; Wu, T.; Leo, D. J.; Winey, K. I.; Moore, R. B.; Long, T. E. Effect of Ionic Liquid on Mechanical Properties and Morphology of Zwitterionic Copolymer Membranes. Macromolecules 2010, 43, 790–796. (27) Stępniak, I.; Andrzejewska, E. Highly Conductive Ionic Liquid Based Ternary Polymer Electrolytes Obtained by in Situ Photopolymerisation. Electrochimica Acta 2009, 54, 5660–5665. (28) D’Angelo, A. J.; Grimes, J. J.; Panzer, M. J. Deciphering Physical Versus Chemical Contributions to the Ionic Conductivity of Functionalized Poly(Methacrylate)-Based Ionogel Electrolytes. J. Phys. Chem. B 2015, 119, 14959–14969. (29) O’Mahony, A. M.; Silvester, D. S.; Aldous, L.; Hardacre, C.; Compton, R. G. Effect of Water on the Electrochemical Window and Potential Limits of Room-Temperature Ionic Liquids. J. Chem. Eng. Data 2008, 53, 2884–2891. (30) Wu, T.; Beyer, F. L.; Brown, R. H.; Moore, R. B.; Long, T. E. Influence of Zwitterions on Thermomechanical Properties and Morphology of Acrylic Copolymers: Implications for Electroactive Applications. Macromolecules 2011, 44, 8056–8063. (31) He, K.; Duan, H.; Chen, G. Y.; Liu, X.; Yang, W.; Wang, D. Cleaning of Oil Fouling with Water Enabled by Zwitterionic Polyelectrolyte Coatings: Overcoming the Imperative Challenge of Oil– Water Separation Membranes. ACS Nano 2015, 9, 9188–9198. (32) Page, Z. A.; Liu, F.; Russell, T. P.; Emrick, T. Rapid, Facile Synthesis of Conjugated Polymer Zwitterions in Ionic Liquids. Chem. Sci. 2014, 5, 2368–2373. (33) Taguchi, S.; Matsumoto, T.; Ichikawa, T.; Kato, T.; Ohno, H. Gelation of an Amino Acid Ionic Liquid by the Addition of a Phosphonium-Type Zwitterion. Chem. Commun. 2011, 47, 11342–11344. (34) Tokuda, H.; Tsuzuki, S.; Susan, M. A. B. H.; Hayamizu, K.; Watanabe, M. How Ionic Are Room-Temperature Ionic Liquids? an Indicator of the Physicochemical Properties. J. Phys. Chem. B 2006, 110, 19593–19600.
4 ACS Paragon Plus Environment
Page 5 of 6
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Chemistry of Materials
(35) Zhang, Y.; Maginn, E. J. Direct Correlation Between Ionic Liquid Transport Properties and Ion Pair Lifetimes: a Molecular Dy-
namics Study. J. Phys. Chem. Lett. 2015, 6, 700–705.
5 ACS Paragon Plus Environment
Chemistry of Materials
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Insert Table of Contents artwork here
6 ACS Paragon Plus Environment
Page 6 of 6
