Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session R50: Ion Transport Mechanisms in Poly(ionic liquids) and Polymer ElectrolytesFocus
|
Hide Abstracts |
Sponsoring Units: DPOLY Chair: Pinar Akcora, Stevens Institute of Technology Room: BCEC 252B |
Thursday, March 7, 2019 8:00AM - 8:12AM |
R50.00001: Decoupling Conductivity and Segmental Motion in Polymerized Ionic Liquids Jordan Keith, Venkatraghavan Ganesan We characterize diffusion trends in polymerized ionic liquids using atomistic molecular dynamics simulations of a number of anion species and imidazolium cations, both tethered to and implanted in poly-alkyl backbones, to develop design guidelines for polymerized ionic liquids with highly decoupled conductivity and polymer segmental dynamics. We use glass-transition-normalized temperature to compare conductivity for similar segmental dynamics behavior across a variety of chemical species. Results suggest that ion mobility decoupling depends on two distinct modes: 1) a small-ion ion-pairing mode where conduction relies heavily on an ion-hopping mechanism that has been explored previously, and 2) a large-ion free-volume diffusion mode that utilizes large, interconnected gaps in the polymer matrix for diffusion in the absence of segmental motion. |
Thursday, March 7, 2019 8:12AM - 8:24AM |
R50.00002: Molecular design of precise network polymerized ionic liquids to control aggregation and conductivity Qiujie Zhao, Chengtian Shen, Christopher Evans Polymerized ionic liquids (PILs) are promising energy storage materials due to their high ionic conductivity and great thermal stability. The structure-property relationships of linear PILs have been extensively studied, yet little is known about other polymer architectures such as networks. We synthesized linear and network PILs containing precise linker lengths between charges using step-growth polymerization. Two different linkers were incorporated, either an 11 carbon chain (C11) or a tetra(ethylene oxide) chain (EO, also 11 atoms), to vary the network polarity. Wide-angle X-ray scattering measurements showed that the ion aggregation peaks were less intense in the EO systems, suggesting that the polar backbone provides better ion solvation. Network PILs had more pronounced ion aggregation peaks than their linear counterparts, indicating a role of polymer architecture on ion clustering. In addition, the EO network showed a two orders of magnitude increase in conductivity relative to the linear analogue at Tg+10°C. We hypothesize that the cross-linked structure provides greater correlation of conduction pathways. This systematic study provides a fundamental understanding on how polymer architecture and polarity can influence the aggregation and transport of ions in PILs. |
Thursday, March 7, 2019 8:24AM - 8:36AM |
R50.00003: Competitive structural and cooperative dynamical heterogeneities of hydrogen bonding and π-type interactions in imidazolium bis(oxalato)borate and polymers Yonglei WANG, Aatto Laaksonen, Michael David Fayer, Jiayin Yuan Delicate intermolecular features like hydrogen bonding (HB) and π-type interactions play pivotal roles in stabilizing molecular structures in ionic liquids (IL) bearing ring planes and HB sites. The nature of these interactions is distinct depending on specific ion types. HB and π-type interactions simultaneously occur in ILs consisting of imidazolium cations coupled with small anions. However, both HB and π-type interactions are considerably weakened when imidazolium cations are associated with large anions. The trade-off between HB and π-type interactions becomes more complicated if anions are featured with ring planes. We performed first-principles and atomistic simulations to explore HB and π-type associations in imidazolium bis(oxalato)borate ILs. Preferential HBs and π-type coordinations among ring planes coexist in ILs. Lengthening alkyl chains in cations leads to a substantial increase in HB strength but decrease in π-π stacking stability between ring structures, indicating a competitive structural feature between HB and π-type associations. A cooperative character is observed in HB dynamics and in reorientations of rings with lengthening alkyl chains in cations. We will explore additional structural and dynamical heterogeneities in polymerized ILs in our ongoing work. |
Thursday, March 7, 2019 8:36AM - 8:48AM |
R50.00004: The Role of Polymer Backbone Chemistry on Ionic Aggregation and Conductivity in Metal-Ligand Coordinating Polymers Nicole Michenfelder-Schauser, My Linh Le, Ram Seshadri, Rachel Segalman Polymeric ionic liquids capable of conducting multivalent ions are based on metal-ligand coordination interactions. This work explores the roles of polymer backbone chemistry, metal-ligand coordination, and ion concentration on ionic conductivity. In these systems, multivalent ion transport is facilitated via ligands pendant to the polymer backbone. While previous results suggest the matrix dielectric constant affects ion dissociation and aggregate structure, this has been studied only in systems where ions interact directly with the polymer backbone. In the case of pendant ligands, it is not clear immediately that the dielectric constant of the backbone would be relevant in determining ion transport. We show for polymers with pendant imidazole ligands, the local dielectric properties of the polymer backbone, based on either poly(ethylene oxide) (PEO) or poly(butadiene) (PBD), still affect ion aggregation and ionic conductivity. While no aggregation is observed at low salt concentration for the PEO-based polymer, Li+, Zn2+ and Cu2+ show aggregation in the PBD polymer resulting in reduced ionic conductivity. This highlights the importance of backbone dielectric properties even in polymer electrolytes with tethered solvating groups. |
Thursday, March 7, 2019 8:48AM - 9:00AM |
R50.00005: Polymerization of a Imidazolium Ionic Liquid Under 2D Confinement and the Resulting Effects on Ion Dynamics Thomas Kinsey, Kaitlin Glynn, Joshua Sangoro We have employed broadband dielectric spectroscopy to probe ion dynamics in 1-ethyl-3-vinylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid (IL) under confinement within ~7nm nanoporous silica membranes. The IL was then polymerized within the pores to a maximum monomer conversion of ~70% as determined using Raman spectroscopy. Compared to the pure systems in bulk, the confined PIL displayed increased ionic conductivity, while the IL displayed decreased ionic conductivity under confinement. To unravel the effects of unconverted monomer and the effects of confinement on the increased ion conduction in the PIL system, a blend of the IL and PIL was prepared at the same monomer to polymer ratio as was achieved during polymerization within the membranes. Decreased conductivity in bulk compared to confinement is described due to aggregation of the IL in the blend with that does not occur within the membranes due to free volume effects. These results are also compared to recent theoretical results from the literature. |
Thursday, March 7, 2019 9:00AM - 9:12AM |
R50.00006: Polymer-Grafted Nanoparticles in Ionic Liquids Siqi Liu, Naresh Osti, Clemens Liedel, Pinar Akcora The newly synthesized zwitterionic liquid (ZIL) 1-butyl-3-methyl imidazole-2-ylidene borane, has superior properties to existing ionic liquids such as good stability in ambient environment. Because it is a zwitterion, there is no self-dissociation of ions, the ion transport and conductivity measured will be due to dynamics of zwitterionic molecule. In this work, deuterated PMMA-grafted nanoparticles with two grafting densities were synthesized. Their dispersion in aprotic ZIL and protic ionic liquid (1-hexyl-3-methylimidazolium bis(trifluormethylsulfonyl)imide) (IL) were investigated in high resolution electron microscopy. We measured dynamics of IL and ZIL with the addition of grafted particles in quasi-elastic neutron scattering experiments. We found translational ionic diffusion of IL slowed down as result of the good mixing and coupling of IL with grafted chains. With the aggregated system, diffusion was similar in bulk, which was due to the phase separation between IL and particles. Interestingly, diffusivity of ZIL increased with the inclusion of particles, particularly with the particles of higher graft density. The increased diffusivity is explained by the confinement of ZIL within structures of grafted nanoparticles. |
Thursday, March 7, 2019 9:12AM - 9:24AM |
R50.00007: Effects of Molecular Architecture on the Simultaneous Enhancement in Modulus and Ionic Conductivity in Polymer Solid Electrolytes Spiros Anastasiadis, Emmanuil Glynos, Paraskevi Petropoulou, Lampros Papoutsakis, Emmanouil Mygiakis, Alkmini D. Nega, Georgios Sakellariou, Wenyang Pan, Emmanuel P. Giannelis In an effort to develop solid polymer electrolytes (SPEs) with enhanced mechanical modulus and ionic-conductivity, we utilize PMMA stars with high functionality as rigid nanoparticle additives to a liquid PEO electrolyte, doped with LiTFSI. The resulting SPEs exhibit two orders of magnitude higher conductivity and one order of magnitude higher mechanical strength compared to their linear PMMA blend analogues. In addition, the former remain solid- like over an extended temperature range. This performance is due to the SPE morphology of dispersed PMMA nanoparticles within the liquid electrolyte host, which allows for the formation of a highly interconnected network of pure liquid electrolyte that leads to high ionic conductivity (comparable to that of the neat PEO electrolyte). |
Thursday, March 7, 2019 9:24AM - 9:36AM |
R50.00008: Increasing Permittivity in Ion-Containing Polymers: Influence of Zwitterion Additives on Ion-Conduction Wenwen Mei, Josh M Rinehart, Josh E Bostwick, Robert Hickey, Ralph H Colby An effective approach to improve the ionic conductivity in ion-containing polymers is to increase the dielectric constant of the host, by adding molecules with large dipole moments. With covalently bonded cation and anion on a single molecule, zwitterions are promising candidates. Despite the high ionic conductivity observed by zwitterion addition in polymerized ionic liquids (PILs), the underlying mechanism remains misunderstood. Here, we studied the change in dielectric constant for a series of sulfonate-imidazolium-based zwitterions blended with glycol solvents using dielectric relaxation spectroscopy (DRS). Adding zwitterions drastically increases the permittivity compared with that of the pure glycol solvents. The Landau-Lifshitz mixing rule describes well the measured permittivities of the blends and was further used to extrapolate to the permittivities of pure zwitterions based on their blend behavior. The dependence of measured permittivity on zwitterion structure, composition, and temperature will be discussed in the context of ion conduction in polymeric materials. The work presented here highlights the exceptional ability of zwitterions to increase permittivity and their potential to boost conductivity of PILs by creating a more polar environment. |
Thursday, March 7, 2019 9:36AM - 9:48AM |
R50.00009: Quantitative Evidence of Mobile Ion Hopping in Polymerized Ionic Liquids Hongjun Liu, Alexei P Sokolov, Stephen J Paddison
|
Thursday, March 7, 2019 9:48AM - 10:00AM |
R50.00010: Ion Transport in Precise Sulfonate Ionomers with Layered, Cylindrical, and Gyroid Morphologies Lu Yan, Christina Rank, Stefan Mecking, Karen Winey Precise spacing of ionic pendant groups along linear polymers produces well-defined nanoscale ion-aggregate morphologies and allows new insights into the ion transport mechanism. In this study, we investigate a series of new ionomers synthesized by polycondensation having sodium (Na+) or tetrabutylammonium ([N(C4H9)4]+) sulfosuccinate segments precisely placed every 23 or 48 backbone carbons of a linear backbone. X-ray scattering studies suggest that these precise semicrystalline ionomers containing sodium sulfosuccinate segments form layered or bicontinuous cubic gyroid ionic nanochannels at room temperature and transition to hexagonal symmetry upon heating. In contrast, those containing tetrabutylammonium sulfosuccinate segments exhibit layered ionic aggregates and transition to liquid-like morphologies upon heating. The temperature dependence of ion transport includes both VFT and Arrhenius behavior and varies with ion aggregate morphology. Overall, increasing cation size from Na+ to [N(C4H9)4]+ leads to faster ion transport due to the enhanced ion dissociation. These precise ionomers provide a promising way to design solid polymer electrolytes with interconnected ionic nanochannels for fast ion transport. |
Thursday, March 7, 2019 10:00AM - 10:12AM |
R50.00011: Nanostructured Polymer Particles for High Modulus and High Conductivity Polymer Electrolytes Emmanouil Glynos, Lampros Papoutsakis, Spiros Anastasiadis, Wenyang Pan, Emmanuel P. Giannelis, Petra Bacova, Vagelis Harmandaris, Emmanouil Mygiakis, Alkmini D. Nega, Georgios Sakellariou We will present a facile new approach for the synthesis of all-polymer nanostructured solid electrolytes that exhibit and unprecedented combination of high modulus and ionic-conductivity at room temperature. Novel nanostructured polymer particles, composed of mikto-arm star-shaped copolymers, were synthesized and used as additives to liquid electrolytes. The mechanical properties of the resulting SPEs are dramatically improved compared to the pure liquid electrolyte (the shear modulus increased by up to 8-orders of magnitude), while the ionic conductivity was maintained close to that of the pure liquid electrolyte. Key to their performance is their morphology that stems from the ability of the mikto-arm copolymers to self-assembly in highly interconnected structures within the liquid electrolytes host. With the help of atomistic molecular dynamics we will show that our strategy offers a tremendous potential for the design of nanostructured polymeric materials where the morphology of the nanostructured SPEs could be precisely controlled as is encrypted within the macromolecular characteristics of the star-shaped nanoparticles. |
Thursday, March 7, 2019 10:12AM - 10:24AM |
R50.00012: Multivalent cation conduction in dual cation-exchanged polyanions Bumjun Park, Jennifer Schaefer Batteries based on active multivalent metal cations are the topic of research worldwide due to the high abundance of these metals. Unfortunately, transport of hard multivalent cations such as Mg2+ and Al3+ in polymers is known to be very slow, due to the strong interactions of these ions with the polar constituents on solvating polymers resulting in chain crosslinking and sluggish coordination site exchange rates. Here we report on the transport of multivalent cations in certain poly(ionic liquids). The inclusion of bulky organic cations is found to reduce the glass transition temperature of the matrix and screen metal multivalent cation interactions, resulting in enhanced ion transport. Characterization of the structure and dynamics of a family of materials incorporating varying organic cation types will be discussed. |
Thursday, March 7, 2019 10:24AM - 11:00AM |
R50.00013: Poly(ionic liquid)s: marriage of ionic liquids and polymers for better materials Invited Speaker: Jiayin Yuan This talk will focus on poly(ionic liquid)s (PILs), a class of multifunctional ionic polymers made up from ionic liquid (IL) monomers. The covalent linkage of IL species into polymeric chains or networks incorporates some unique properties of ILs into that of macromolecular architectures. This innovation in structure design catalyzes new chemistry and physics, and in turn expands the property and function window of ILs and traditional polyelectrolytes.1-3 |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700