Bulletin of the American Physical Society
APS March Meeting 2018
Volume 63, Number 1
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session R43: Mechanisms of Ionic Conduction and Diffusion in Polymeric Ion Conductors IFocus
|
Hide Abstracts |
Sponsoring Units: DPOLY Chair: Moon Jeong Park, Pohang University of Science & Technology Room: LACC 503 |
Thursday, March 8, 2018 8:00AM - 8:36AM |
R43.00001: Ionic Liquids Inspiring the Design of Charged Polymers: The Allure of Phosphorus Invited Speaker: Timothy Long Ionomers and polyelectrolytes represent families of macromolecules that incorporate cationic or anionic sites either pendant or within the polymer main chain. These charged compositions enable tunable physical properties such as ionic conductivity, thermal and chemical stability, water transport, and anion exchange capability. Ion-containing polymers are versatile materials that continuously enable emerging technologies such as water purification, gas separation, gene delivery, biosensors, fuel cells, and electro-mechanical devices. Ionic liquids continue to inspire the design of new families of ionomers and polyelectrolytes. This lecture will present a library of novel monomer strategies wherein the monomers are tailored with a nitrogen or phosphorous site that is capable of efficient alkylation either using a functional monomer strategy or post-polymerization modification. Living anionic and controlled radical polymerization methods enable the preparation of diverse families of ammonium, imidazolium, and phosphonium containing block copolymers, where the placement of the charged site in a low glass transition temperature sequence provides superior performance. The role of block copolymer morphology is critical in determining both water and ion transport properties. The lecture will also highlight an unprecedented step-growth polymerization process leading to a new family of melt processable phosphonium based ionenes whose diversity is further enriched upon anion exchange to finely tune thermomechanical and rheological performance. The design of charge containing polymers relative to tailored hydrogen bonding sites will be presented, and recent advances in nucleobase-containing acrylates will exemplify potential synergies. The impact of novel multiphase, hydrogen bond and ion-containing polymeric systems on adhesion, electro-active membranes, drug delivery, and 3D printing will be discussed. |
Thursday, March 8, 2018 8:36AM - 8:48AM |
R43.00002: Molecular Dynamics and Charge Transport in Highly Conductive Polymeric Ionic Liquids Falk Frenzel, Ryan Guterman, A. Markus Anton, Jiayin Yuan, Friedrich Kremer Glassy dynamics and charge transport are studied for the polymeric ionic liquid (PIL) poly[tris(2-(2-methoxyethoxy)ethyl)ammonium acryloxypropyl sulfonate (PAAPS) with varying molecular weight (9700, 44200, 51600, and 99500 g/mol) by broadband dielectric spectroscopy (BDS) in a wide frequency (10-2-107 Hz) and temperature range (100-400 K) and by DSC- and AC-chip calorimetry. The dielectric spectra are characterized by a superposition of (i) relaxation processes, (ii) charge transport, and (iii) electrode polarization. The proportionality between the relaxation rate of the dynamic glass transition and the charge carrier hopping rate reflects the nature of charge transport as glass transition assisted hopping. Hereby, the PIL under study exposes the highest dc conductivity values observed for this class of materials below 100 °C, so far; and for the first time a conductivity increase by rising degree of polymerization. The comparison of the polymeric ionic liquids under study with others implies conclusions on the design of novel highly conductive PILs. |
Thursday, March 8, 2018 8:48AM - 9:00AM |
R43.00003: Impact of Cation and Counterion Chemical Structure on Ion Transport and Morphology in Cyclopropenium-Based Polymerized Ionic Liquids Benjamin Paren, Philip Griffin, Jessica Freyer, Karen Winey, Luis Campos Polymerized ionic liquids are being explored as promising polymer electrolytes. Optimizing the electrochemical benefits of ionic liquids with the enhanced mechanical stability of a polymer backbone has the potential to create a mechanically robust, non-volatile electrolyte for batteries or fuel cells. This study investigates the structure and conductivity of trisaminocyclopropenium (TAC)-based monomeric and polymerized ionic liquids (mono-ILs and poly-ILs). Differential scanning calorimetry, X-ray scattering, and broadband dielectric spectroscopy are used to measure the local morphological and ion transport properties in the poly-ILs and mono-ILs. The poly-IL systems examined include polystyrene (PS)-TAC with different counterions and cation-modified chemistries of PS-TAC with chlorine counterions. While the mono-ILs have higher conductivity at most temperatures (1-2 orders of magnitude at 50°C), decoupling of the ions is apparent in the poly-IL systems below the glass transition, which leads to higher conductivity in some of the poly-IL systems below ambient temperature. Changing the functional groups of the TAC cations results in large changes to the glass transition, allowing for optimization of the poly-IL systems at different temperatures. |
Thursday, March 8, 2018 9:00AM - 9:12AM |
R43.00004: The Role of Multivalent Ions on the Mechanics and Ionic Conductivity of Metal-Ligand Coordinating Polymers Nicole Michenfelder-Schauser, Gabriel Sanoja, Joshua Bartels, Christopher Evans, Matthew Helgeson, Ram Seshadri, Rachel Segalman Decoupling mechanical properties and ionic conductivity in conventional ion conducting polymers is challenging due to the highly correlated nature of ion motion and segmental chain dynamics. Polymeric ionic liquids (PILs) formed via metal-ligand coordination interactions present a promising pathway towards this goal. This work explores the effect of the nature and concentration of metal cations and ligands in PILs on both mechanical properties and ionic conductivity. Rheological analysis of the addition of metal salts into a ligand-containing polymer suggests the formation of temporary networks. Impedance spectroscopy reveals comparable conductivities for monovalent, divalent and trivalent salts, suggesting conductivity is governed by the ratio of cations to ligands rather than valency, total ion concentration, or strength of the metal-ligand interaction. Pulse-field-gradient NMR diffusion measurements enable a comparison of measured conductivity to conductivity calculated from the Nernst-Einstein equation assuming full salt dissociation. These results suggest a contribution to the conductivity from cation species in the multivalent salt systems. |
Thursday, March 8, 2018 9:12AM - 9:24AM |
R43.00005: The Influence of Polymer Molecular Weight on Transport Properties in Polymerized Ionic Liquids Jordan Keith, Santhosh Mogurampally, Faisal Aldukhi, Bill Wheatle, Venkatraghavan Ganesan We report results from atomistic molecular dynamics simulations on polymerized 1-butyl-3-vinylimidazolium-PF6- ionic liquids, studying the influence of the polymer molecular weight on the ion mobilities and mechanisms underlying ion transport. We present results for ionic diffusivity, ion-association dynamics, ion hopping, and ion-polymer coordination behavior. With increasing polymer molecular weight, the diffusivity of PF6- ions is seen decrease and plateaus above seven repeat units. The diffusivity is seen to correlate well with the ion-association structural relaxation time for pure ionic liquids, but becomes more correlated with the average ion-association lifetime for larger molecular weight polymers. By analyzing the diffusivity of ions based on coordination structure, we unearth a transport mechanism in which the PF6- moves by “climbing the ladder” while associated with four polymeric cations from two different polymers. |
Thursday, March 8, 2018 9:24AM - 9:36AM |
R43.00006: Quantitative Structure Analysis of Polymerized Ionic Liquids with Atomistic Simulations Hongjun Liu, Stephen Paddison The design of solid-state electrolytes for electrochemical applications that utilize polymerized ionic liquids (polyILs) would greatly benefit from a molecular-level understanding of structure-property relationships. We herein use atomistic molecular dynamics simulations to investigate the structural properties of a homologous series of poly(n-alkyl-vinylimidzolium bistrifluoromethylsulfonylimide) poly(CnVim Tf2N). Excellent X-ray S(q) agreement is found in terms of peak position and shape. The quantitative cluster analysis along with color-coded snapshots vividly demonstrates the morphology evolution. Moreover, we exploit the selective labeling neutron scattering to afford further insight. The neutron scattering profiles markedly depend on the isotopic substitution pattern. The neutron S(q) of the backbone deuterated samples reveal the most noticeable low-q peak. We also investigate a model ammonium based polyILs and anion effect. We hope these insights will pave a path forward towards the rational design of future polyILs for electrochemical devices. |
Thursday, March 8, 2018 9:36AM - 9:48AM |
R43.00007: Dynamic-Mechanical and Dielectric Evidence of Long-Lived Mesoscale Organization in Ionic Liquids Joshua Sangoro, James Cosby, Yangyang Wang Experimental evidence of the dynamics of mesoscopic structure in room temperature ionic liquids - a feature expected to correlate with many physicochemical properties of these materials - remains limited. Here, we report the observation of slow, sub-α relaxations corresponding to dynamics of nanoscale hydrophobic aggregates in a systematic series of 1-alkyl-3-methylimidazolium-based ionic liquids from detailed analysis of dynamic-mechanical and broadband dielectric spectra. The emergence of the sub-α relaxations correlates with increases in the zero-shear viscosity and static dielectric permittivity, constituting direct evidence of the influence of mesoscale aggregation on the physicochemical properties of ionic liquids. |
Thursday, March 8, 2018 9:48AM - 10:00AM |
R43.00008: Modulating ion transport properties of PEO-based polymer electrolytes through end-group chemistry Ha Young Jung, Moon Jeong Park The most widely investigated solid polymer electrolytes to dates are based on polyethylene oxide (PEO) owing to its low glass transition temperature and good solvating capability for wide variety of salts. Inherently poor mechanical stability of PEO has prompted various approaches to improve modulus of PEO-based polymers, mostly by linking hard polymer chains and/or incorporating inorganic fillers. This is to prevent dendrite formation at the electrolyte/electrode interfaces; however, it has been found that these approaches are intimately connected to the reduction of ionic conductivity of the resultant polymer electrolytes. In this study, we show a new methodology for improving ion transport properties and mechanical strength simultaneously by introducing various terminal groups in PEO-based polymers. Particularly, by modifying the chain-end with high dipole moment molecules, significant reduction in PEO crystallinity, noticeable increase in the dielectric constant of PEO, and enhancement of storage modulus of the polymers have been achieved. These positive aspects offer effective solvation of lithium salts and amplified intermolecular interactions, tied to improved lithium ion transport properties. |
Thursday, March 8, 2018 10:00AM - 10:12AM |
R43.00009: Enhanced Conductivity Pathways in Block Polymer Electrolytes with Homopolymer Additives Melody Morris, Velencia Witherspoon, Ryan Nieuwendaal, Thomas Epps Block polymer (BP) electrolytes are an attractive alternative to current liquid electrolyte materials for lithium-ion batteries because of their ability to decouple ionic conductivity, modulus, and thermal properties, thereby enhancing performance and stability. To increase the ionic conductivity, A-b-B BPs were blended with A homopolymers, where A was the ion-solvating component, and doped with a series of lithium salts. The homopolymer distributions in the BP were determined via neutron reflectometry by leveraging the scattering length density contrast between deuterated homopolymer and non-deuterated BP. To access the wet and dry brush regimes, various homopolymer molecular weights were employed. The homopolymer distributions were correlated to the conductivity (via AC impedance spectroscopy) and glass transition temperature (via differential scanning calorimetry) to elucidate the effects of homopolymer blending on physical and transport properties. Finally, solid-state nuclear magnetic resonance spectroscopy was used to determine the effect of homopolymer blending on the relative populations of mobile and immobile lithium ions in the nanostructured polymer blend electrolytes. |
Thursday, March 8, 2018 10:12AM - 10:24AM |
R43.00010: Structure-function Properties of Microphase Separated Ion Conducting Block Copolymer Thin Films Yu Kambe, Christopher Arges, Yamil Colon, Weiwei Chu, Juan De Pablo, Paul Nealey In this talk, we will discuss the role of the ion conduction path on the electrochemical behavior of ion conducting block copolymer (BCP) thin films. A BCP thin film with one ion conducting block (poly(2-vinyl n-methylpyridinium iodide)) and one ion insulating block (polystyrene) was micro-phase separated into a variety of conduction paths on top of interdigitated electrodes (IDEs). A random copolymer was grafted onto the IDE surface to align the domains perpendicular to the surface. Therefore, simple top down surface metrology techniques could be used to characterize all of the ion conduction pathways from one electrode to the other. The conductivity and capacitance values, calculated from complex impedance spectra, changed by orders of magnitude when the morphology of the BCP film was altered. Additionally, visual analysis of the conduction paths along with molecular dynamic simulations were used to predict the measured resistance of the film within experimental error. |
Thursday, March 8, 2018 10:24AM - 10:36AM |
R43.00011: Probing Ion Dynamics in Solid Polymer Blend Electrolytes via T1-T2 Correlation NMR and Inversion of the Laplace Transform Luis Smith, Sergio Granados-Focil NMR spectroscopy can provide element specific information on ion motion in solid polymer electrolytes via relaxation rate studies. Local motions can be inferred from measurements of longitudinal, T1, and spin-spin, T2, relaxation mechanisms, however extraction of correlation times can be challenging due to the distributions of dynamics present in these systems. The inversion of the Laplace transform can extract relaxation rate distributions in a decay process. When used with T1-T2 correlation NMR experiments, the dynamic environments can be observed and aspects of the distributions dissected in terms of correlation time, electric field gradient, and dipolar coupling to hydrogen in the polymer. This approach has been applied to the study of a single-ion conductor made from blends of linear poly(ethyleneimine)-graft-poly(ethylene glycol) with linear poly(ethyleneimine) bearing lithium N-propylsulfonate groups. While conductivities of 10-3 S/cm are observed, the amount of free lithium ion participating in conductivity is not obvious and data on lithium ion dissociation from the N-propylsulfonate group is needed. Using correlation spectroscopy, the varying lithium populations as a function of temperature and Li:O ratio will be presented and the utility of this method described. |
Thursday, March 8, 2018 10:36AM - 10:48AM |
R43.00012: Principles of Static and Dynamic Flexoelectricity in Viscoelastic Solid Polymer Electrolyte Membranes Jinwei Cao, Camilo Piedrahita, Zhiyang Zhao, Bryan Vogt, Thein Kyu Inspired by the basic principles of bioelectricity and signal transmission in neurons, a multilayer laminate consisting of flexible solid polymer electrolyte membranes (PEM) and flexible carbonaceous electrodes has been fabricated. The laminated PEM generates electrical voltage/current via ion shuttling or pumping during PEM bending/flexing and therefore may be used for harvesting energy from wind and tidal waves. Flexoelectricity operates based on the principle of ‘bending’ piezoelectricity, wherein electricity is produced via ion polarization during mechanical deformation. To determine the flexoelectric property of the PEM system, a unique experimental setup has been designed by combining dynamic mechanical analyzer (DMA) and Solartron Potentiostat/Galvanostat. DMA serves as an actuator for cantilever bending/flexing of the PEM sample, whereas Solartron instrument monitors the electrical energy output. The flexoelectric coefficient, ion polarization density, and electrical energy output have been determined under static and dynamic oscillatory flexing modes and subsequently flexoelectric principles of viscoelastic PEMs will be discussed. |
Thursday, March 8, 2018 10:48AM - 11:00AM |
R43.00013: Flexoelectric Effect in Solid-state Polymer Electrolyte Membrane during Mechanical Deformation Camilo Piedrahita, Jinwei Cao, Thein Kyu Ion diffusion is a chemical driving force for electrical power generation and signal transmission in neuron cells. There are two types of ion diffusion; passive and active. Passive diffusion is due to ion movement driven by ion concentration gradient across the membrane, which is the energy restoration process of the solid-state Li-ion batteries. During battery resting, after being fully discharged, only ~8% of energy was recovered. Alternatively, active diffusion of ions may be sought, which occurs when subjected a pressure gradient, i.e., ion pumping. In this work, the active ion diffusion process has been investigated under pressure (stress or strain) gradients across the solid polymer electrolyte membrane (PEM). Under an applied electric field, the solid PEM undergoes bending deformation and vice versa, an electric field is produced when the PEM is bent, which may be attributed to ion polarization. Of particular interest is that the flexoelectric coefficients of several PEMs, as determined under static experiment were found to be orders of magnitude greater than its counter parts - ferroelectric ceramic crystals and bent-core liquid crystals. |
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