Bulletin of the American Physical Society
APS March Meeting 2016
Volume 61, Number 2
Monday–Friday, March 14–18, 2016; Baltimore, Maryland
Session C33: Polymers in Batteries and Electrochemical CapacitorsFocus
|
Hide Abstracts |
Sponsoring Units: DPOLY Chair: David Hallinan, Florida State University Room: 336 |
Monday, March 14, 2016 2:30PM - 2:42PM |
C33.00001: Exploring Strategies for High Dielectric Constant and Low Loss Polymer Dielectrics Lei Zhu Polymer dielectrics having high dielectric constant, high temperature capability, and low loss are attractive for a broad range of applications such as film capacitors, gate dielectrics, artificial muscles, and electrocaloric cooling. Unfortunately, it is generally observed that higher polarization or dielectric constant tends to cause significantly enhanced dielectric loss. It is therefore highly desired that the fundamental physics of all types of polarization and loss mechanisms be thoroughly understood for dielectric polymers. In this presentation, we intend to explore advantages and disadvantages for different types of polarization. Among a number of approaches, dipolar polarization is promising for high dielectric constant and low loss polymer dielectrics, if the dipolar relaxation peak can be pushed to above the gigahertz range. In particular, dipolar glass, paraelectric, and relaxor ferroelectric polymers are discussed for the dipolar polarization approach. [Preview Abstract] |
Monday, March 14, 2016 2:42PM - 2:54PM |
C33.00002: Energy conversion in polyelectrolyte hydrogels Monica Olvera de la Cruz, Aykut Erbas Energy conversion and storage have been an active field of research in nanotechnology parallel to recent interests towards renewable energy. Polyelectrolyte (PE) hydrogels have attracted considerable attention in this field due to their mechanical flexibility and stimuli-responsive properties. Ideally, when a hydrogel is deformed, applied mechanical work can be converted into electrostatic, elastic and steric-interaction energies. In this talk, we discuss the results of our extensive molecular dynamics simulations of PE hydrogels. We demonstrate that, on deformation, hydrogels adjust their deformed state predominantly by altering electrostatic interactions between their charged groups rather than excluded-volume and bond energies. This is due to the hydrogel's inherent tendency to preserve electro-neutrality in its interior, in combination with correlations imposed by backbone charges. Our findings are valid for a wide range of compression ratios and ionic strengths. The electrostatic-energy alterations that we observe in our MD simulations may induce pH or redox-potential changes inside the hydrogels. The resulting energetic difference can be harvested, for instance, analogously to a Carnot engine, or facilitated for sensor applications. [Preview Abstract] |
Monday, March 14, 2016 2:54PM - 3:06PM |
C33.00003: Sulfone-Containing Dipolar Glass Polymers with High Dielectric Constant and Low Loss Property Yufeng Zhu, Zhongbo Zhang, Morton Litt, Lei Zhu Sulfone-containing polyoxetanes are designed and synthesized for high dielectric constant and low loss dipolar glasses. The precursor polymer, poly(3,3-bis(chloromethyl)oxetane) (PBCMO) is synthesized by bulk cationic polymerization with boron trifluoride diethyl etherate as initiator. The number-average molecular weight of PBCMO is 73 kDa, with a polydispersity of 1.53 as obtained from size-exclusion chromatography results. Post-modification of PBCMO yields the dipolar glass polymer, poly(3,3-bis(methylsulfonylmethyl)oxetane) (MST). Nuclear magnetic resonance result shows 100{\%} conversion. Differential scanning calorimetry result indicates that MST has a glass transition temperature of ca. 120 \textdegree C. Due to the large dipole moment (4.25 D) and small size of the side-chain sulfone groups, MST exhibits a high dielectric constant of 8.7 and a low dissipation factor of 0.01 at 25 \textdegree C and 1 Hz. This study suggests that dipolar glass polymers with large dipole moments and small-sized dipoles in the side chains are promising candidates for high energy density and low loss dielectric applications. [Preview Abstract] |
Monday, March 14, 2016 3:06PM - 3:18PM |
C33.00004: Generalized Ferroelectricity in the Mesomorphic Phase of Nylon Polymers Zhongbo Zhang, Lei Zhu, Morton Litt Novel ferroelectric polymers, featured by narrow electric displacement-electric (D-E) hysteresis loop, are attractive for electric energy storage applications due to their high dielectric constant and low loss property. Currently, only poly(vinylidene fluoride) (PVDF)-based copolymers (e-beamed) and terpolymers show novel ferroelectric behavior. It is desired to achieve novel ferroelectricity in other polymers such as nylons by carefully modifying the chemical and crystal structures. In this presentation, isomorphic crystals are successfully achieved by copolymerization of nylon 11 and nylon 12 with different compositions. In this way, both chemical and structural defects (i.e., dangling amide groups and kinked bonds) are introduced into the mesomorphic phase. As a consequence, hydrogen bonding interaction is successfully weakened and thus enhanced ferroelectricity with higher maximum polarization and better polarizability is obtained. In addition, for the purpose of further disturbing the mesomorphic phase and pinning effect, partially methylated nylon copolymers are synthesized. With the help of N-methylation of amide groups, the methylated nylon copolymers show relatively narrow hysteresis loops, suggesting the pinning effect from the N-methylated amide moieties. [Preview Abstract] |
Monday, March 14, 2016 3:18PM - 3:30PM |
C33.00005: Nanostructure and free volume effects in enhancing the dielectric response of strongly dipolar polymers Rui Dong, Yash Thakur, Vivek Ranjan, Marco Buongiorno Nardelli, Qiming Zhang, Jerry Bernholc Materials for capacitive energy storage with high energy density and low loss are desired in many fields. We perform multiscale simulations to investigate several members of the aromatic polyurea family. We find that the disordered structures with misaligned chains have considerably larger dielectric constants, due to significant increase in the free volume, which leads to easier reorientation of dipolar groups in the presence of an electric field. Large segment motion is still not allowed below the glass transition temperature, upholding the very low loss at high field and elevated temperature that we observe experimentally. Optimization of the nanostructure and free volume effects thus provides a new, very promising pathway for the design of high-performance dielectrics for capacitive energy storage. [Preview Abstract] |
Monday, March 14, 2016 3:30PM - 3:42PM |
C33.00006: Azobenzene Modified Polymer Electrolyte Membrane for Ion Gating Camilo Piedrahita, Mireille Mballa, Ruixuan He, Thein Kyu By virtue of ion concentration gradient across cell membranes, neuron cells are highly polarized driving electrical potential difference (e.g., Gibbs law). To regulate and control ion movement, living cells have specific channels with gates that are permeable to cations, enabling or excluding them via charge polarity and size. This mechanism for generating and transmitting signals from one neuron to another controls body movement via brain function. By virtue of trans-cis isomerization, azobenzene derivative (AZO) has been heavily sought for ion-gating in biological cells as a means of signal generation and transmission through nervous systems. In this work, PEM consisted of PEGDA/SCN/LiTFSI was modified with AZO derivatives for gating of lithium ions. At low concentrations of azobenzene of 3 wt%, the AZO - PEM mixture is isotropic, but phase separation takes place with increasing AZO. With AZO modification, the ionic conductivity initially declines, but the conductivity increases with further increase of AZO concentration. Upon UV photopolymerization, segregated AZO molecules are presumably entrapped in the cis-state. The cis-to-trans transformation opens the AZO gates to Li+, resulting in enhanced ion transport. [Preview Abstract] |
Monday, March 14, 2016 3:42PM - 3:54PM |
C33.00007: Molecular Dynamics Simulation of Ion Solvation in Polymer Melts: Effects of Dielectric Inhomogeneity and Chain Connectivity on Solvation Energy of Ions Lijun Liu, Issei Nakamura We study the ion solvation in block copolymer melts and polymer blends using molecular dynamics simulations. In our simulations, polymers are formed through the connection of beads that provide the dielectric response. Thus, we highlight the effect of the dielectric contrast between different species on the solvation energy of ions. We demonstrate the local enrichment of higher-dielectric components near ions, which corresponds well with the result of mean-field theories. Moreover, the chain connectivity significantly affects the reorientation of molecular dipoles in response to the electrostatic field from ions. Thus, we illustrate the marked difference in the solvation energy between the block copolymer and polymer blend. Importantly, the solvation energy substantially depends on the chain length of the polymers, in stark contrast to the Born solvation energy. We also show that our simulation results exhibit striking similarity to the result of the recent self-consistent mean field theories. However, for strongly correlated dipoles and ions, our simulations provide qualitatively opposite behaviors to these results, suggesting further development of the theoretical frameworks. [Preview Abstract] |
Monday, March 14, 2016 3:54PM - 4:06PM |
C33.00008: A new lattice Monte Carlo method for simulating dielectric inhomogeneity Xiaozheng Duan, Zhen-Gang Wang, Issei Nakamura We present a new lattice Monte Carlo method for simulating systems involving dielectric contrast between different species by modifying an algorithm originally proposed by Maggs et al. The original algorithm is known to generate attractive interactions between particles that have different dielectric constant than the solvent. Here we show that such attractive force is spurious, arising from incorrectly biased statistical weight caused by the particle motion during the Monte Carlo moves. We propose a new, simple algorithm to resolve this erroneous sampling. We demonstrate the application of our algorithm by simulating an uncharged polymer in a solvent with different dielectric constant. Further, we show that the electrostatic fields in ionic crystals obtained from our simulations with a relatively small simulation box correspond well with results from the analytical solution. Thus, our Monte Carlo method avoids the need for the Ewald summation in conventional simulation methods for charged systems. [Preview Abstract] |
Monday, March 14, 2016 4:06PM - 4:18PM |
C33.00009: Effect of Eutectic Concentration on Conductivity in PEO:LiX Based Solid Polymer Electrolytes Pengfei Zhan, Lalitha Ganapatibhotla, Janna Maranas Polyethylene oxide (PEO) and lithium salt based solid polymer electrolytes (SPEs) have been widely proposed as a substitution for the liquid electrolyte in Li-ion batteries. As salt concentration varies, these systems demonstrate rich phase behavior. Conductivity as a function of salt concentration has been measured for decades and various concentration dependences have been observed. A PEO:LiX mixture can have one or two conductivity maximums, while some mixtures with salt of high ionic strength will have higher conductivity as the salt concentration decrease. The factors that affect the conductivity are specific for each sample. The universal factor that affects conductivity is still not clear. In this work, we measured the conductivity of a series of PEO:LiX mixtures and statistical analysis shows conductivity is affected by the concentration difference from the eutectic concentration ($\Delta $c). The correlation with $\Delta $c is stronger than the correlation with glass transition temperature. We believe that at the eutectic concentration, during the solidification process, unique structures can form which aid conduction. [Preview Abstract] |
Monday, March 14, 2016 4:18PM - 4:54PM |
C33.00010: Status of Li-polymer batteries for vehicle applications Invited Speaker: Venkat Srinivasan Polymer-based batteries have the potential to revolutionize energy storage because of their ability to allow lithium metal anodes to be used, thereby promising higher energy densities. In addition, there have been vast strides in tuning polymers specific to battery applications, including the use of mixed conductors that provide both electronic and ionic conduction, and multifunctional polymers that serve as, for example, conductors and binders. There has been renewed interest in this topic recently, in the context of solid-state batteries. However, it is still not clear if the properties of presently available solid electrolytes are sufficient to meet the targets for electric vehicle applications. In this talk, we will present a material-to-cell level analysis of solid electrolytes to access the status of presently available materials. Continuum scale models will be used with experiments to understand the underlying processes in the battery and to project energy and power capabilities of solid-state cells based on their material properties. The models use appropriate material properties, where available, and are compared to experimental data to ensure validity. The validated model is then used to estimate the cell-level energy and power capability following the testing protocols specific to electric vehicle application. This analysis helps to identify existing challenges and provides guidelines for research at both material and cell levels for this promising class of next-generation batteries. [Preview Abstract] |
Monday, March 14, 2016 4:54PM - 5:06PM |
C33.00011: Pendant Dynamics of Ethylene-Oxide Containing Polymers with Diverse Backbones Joshua Bartels, Jing-Han Helen Wang, Quan Chen, James Runt, Ralph Colby In the last twenty years, a wide variety of ion conducting polymers have used ether oxygens to facilitate ion conduction, and it is therefore important to understand the dynamics of ether oxygens (EOs) when attached to different polymer backbones. Four different EO-containing polymer architectures are studied by dielectric spectroscopy to understand the backbone effect on the EO dipoles. Polysiloxanes, polyphosphazenes, polymethylmethacrylates, and a polyester ether are compared, with different EO pendant lengths for the siloxane and methylmethacrylate backbones. The flexible polysiloxanes and polyphosphazene backbones impart superior segmental mobility with a glass transition temperature ~15 K lower than that of the organic backbone polymers. Short EO pendants are found to impart a lower static dielectric constant at comparable EO content as compared to longer EO pendants of either inorganic or organic backbones. The long-pendant polymethylmethacrylate polymers show two relaxations corresponding to fast EOs near the pendant tail end and slow EOs close to the slower backbone, whereas the long-pendant polysiloxane shows a single relaxation due to the siloxane backbone relaxing faster than the EO pendant. [Preview Abstract] |
Monday, March 14, 2016 5:06PM - 5:18PM |
C33.00012: \textbf{Understanding self-assembly of charged--neutral block copolymer (BCP) and surfactant complexes using molecular dynamics (MD) simulation} Monojoy Goswami, Bobby Sumpter, Michael Kilbey Here we report the formation of phase separated BCP-surfactant complexes resulting from the electrostatic self-assembly of charge-neutral block copolymers with oppositely charged surfactants. Complexation behaviors of oppositely charged polyelectrolytes has gained considerable attention in the field of soft condensed matter physics due to their potential application as functional nanomaterials for batteries, wastewater treatment and drug delivery systems. Numerous experiments have examined the self-assembled structures resulting from complexation of charge-neutral BCP and surfactants, however, there is a lack of comprehensive understanding at the fundamental level. To help bridge this gap, we use, MD simulations to study self-assembly and dynamics of the BCP-surfactant complex at the molecular level. Our results show an overcharging effect in BCPs with hydrophobic neutral blocks and a formation of core-shell colloidal structure. Hydrophilic neutral blocks, on the other hand, show stable, hairy colloidal structures with neutral blocks forming a loosely-bound, fuzzy outer layer. Our results qualitatively agree with previous SANS and SAXS experiments. [Preview Abstract] |
Monday, March 14, 2016 5:18PM - 5:30PM |
C33.00013: Charge transport and structural dynamics in nanoscale confined ionic liquids: role of the dimensionality of confinement Joshua Sangoro, Maximilian Heres, Tyler Cosby Charge transport and structural dynamics in systematic series of low molecular weight and polymerized ionic liquids (ILs) confined in nanopores and as thin films are investigated by broadband dielectric spectroscopy. Detailed analysis of the dielectric spectra of ILs confined in unidirectional nanopores with mean diameters down to 3 nm and ultra thin polymer films with thicknesses down to 5 nm reveal that the dimensionality of confinement plays a crucial role in determining the resultant ion transport properties in confined ionic liquids. In this talk, the impact of the dimensionality of confinement on ion transport and dynamics will be discussed within the framework of current theories of charge transport and glassy dynamics. [Preview Abstract] |
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