Download or read book Investigation of Charge Transport and Mechanical Properties in Ion Associating Polymeric Materials written by Joshua Everett Bostwick and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Gel polymer electrolytes (GPEs) are ion-conducting polymers where the polymer matrix is swollen with a certain amount of solvent. While GPEs are able to take advantage of both the mechanical properties of the polymer matrix and the conductive properties of the solvent, they are limited due to the inverse relationship between the ionic conductivity ([sigma]o) and the modulus, diminishing their potential as next generation lithium-ion battery electrolytes. In this dissertation, we studied the fundamental properties of three different GPEs, molecular ionic composites (MICs) where the solvent is an ionic liquid (IL), single-ion-based MICs where the 'solvent' is poly(ethylene glycol), and cellulose-ionic liquid solutions, for their potential use as battery electrolytes. MICs utilize the mechanical and thermal stability of a rigid-rod sulfonated polyelectrolyte, poly(2,2')-disulfonyl-4,4'benzidine terephthalamide (PBDT), and the high conductivity, electrochemical stability, and low volatility of ILs. This allows the MICs to produce a simultaneous high modulus (from the PBDT) and a high conductivity (from the IL). The first half of this dissertation explores how the change in either the PBDT concentration with a constant IL or the IL molecular volume (Vm) and chemistry with a constant PBDT concentration affects both the mechanical and charge transport properties of the MICs. The varying PBDT concentration MICs were produced via an ion exchange method to form 3 mm diameter cylinders (ingots) while the varying IL Vm MICs were produced via solvent casting to form six free-standing films. The single-ion PBDT membranes were also formed via the solvent casting method. The mechanical properties were measured using a combination of oscillatory shear rheology and uniaxial tensile tests (only for the films), while the dielectric properties and morphology of the films were determined through dielectric relaxation spectroscopy (DRS) and atomic force microscopy (AFM) respectively. Increasing the MIC PBDT concentration with a constant IL, 1-butyl- 3-methylimidazolium tetrafluoroborate (BMIm-BF4), showed a minimal change in dynamic glass transition temperature (Tg) of roughly 2 °C through rheology with its respective IL. This allowed for the MIC ionic conductivity ([sigma]o) at elevated PBDT concentrations to be within a factor of two of the neat IL at room temperature while also producing a shear modulus (G') in the MPa range up to 200 °C. This is due to the MICs producing a two-phase environment corresponding to an IL-rich "puddle" phase and a PBDT-rich "bundle" phase, shown through the phase contrast in atomic force microscopy (AFM), where IL ions form alternating sheaths of cations and anions around each PBDT rod. As the PBDT concentration increases, these puddles shrink and produce a near single bundle phase. This potentially increases the polarizability of the MIC, shown by an increasing static dielectric constant, as well as allowing for more IL ions to contribute to [sigma]o shown by a decrease in the Haven ratio (HR), the ratio between the total number of charge carriers observed through NMR and the number conductive charge carriers that can be analyzed through the ionic conductivity. Incorporating ILs with different molecular volumes (Vm) and chemistries in the MICs with a constant PBDT concentration showed that all MICs maintain low Tgs, ranging between 0 -- 8 °C above their respective neat IL. This was confirmed through analyzing the derivative spectra from DRS to determine the dynamic Tg as well as measuring the thermal Tg through differential scanning calorimetry (DSC). The agreement in Tg between these two methods suggests that the glassy dynamics of MICs is dictated by the rearrangement of IL ions during charge transport. All MICs are able to produce high [sigma]o, ranging from 1 -- 6 mS cm-1 at 30 °C with smaller imidazolium-based cations producing higher [sigma]o than MICs with larger imidazolium cations and similar anions due to their larger molar conductivity. Tensile measurements showed that all MICs produce IL-dependent Young's modulus (E), ranging from 50 -- 500 MPa at 30 °C, up to 60 x higher when compared to the G' of the same MICs. We propose this is due the difference in the distribution of PBDT chains between the shear and tensile planes as well as the competing interactions between the IL ions and the PBDT rods. This hypothesis is supported by the AFM phase contrast images, where the 1-ethyl- 3-methylimidazolium (EMIm+) based MICs show the largest formation of the bundle phase (with very small puddles) while the BMIm+ based MICs produce a larger puddle phases as the anion Vm decreases, thus lowering E. Relating the [sigma]o to their corresponding diffusive coefficients through the Nernst-Einstein shows that all MIC have an ionicity (inverse Haven ratio, HR--1) range between 0.54 -- 0.63, suggesting that a fraction of the diffusive ions do not contribute to charge transport. Along with the IL-based MICs, we analyzed the dielectric and mechanical dynamics of single-ion conducting PBDT-based membranes by incorporating poly(ethylene glycol) with a molecular weight of 400 g mol-1 (PEG400) and either Na+ or Li+ counterions are studied in detail. Varying the PBDT and PEG400 wt% allowed for the preparation of varying PBDT concentrated membranes. All membranes have low DSC Tgs, regardless of counterion attached to the PBDT and the Tg increases with elevated PBDT concentration. The ionic conductivity of the membranes systematically decreases with increasing PBDT concentration, ranging from 0.1 -- 7 [mu]S cm-1` at 30 °C and reaching 100 [mu]S cm-1 at 120 °C in the lowest NaPBDT concentration film. Normalizing the temperature-dependent ionic conductivities divided by their respective Coulombic dielectric constant by the dynamic DRS Tg show that all data roughly collapse onto a single curve, suggesting that the glassy dynamics are dictated the speed of the diffusive motion and the dissociation of ion-pairs produced from strong ionic interactions in the membrane. Tensile stress-strain analysis on the membranes reveal that the E is dominated by the counterion used with the Na+-based membranes producing an E ranging from approximately 100 -- 400 MPa while the Li+-based membranes produced an E ranging from approximately 300 -- 2100 MPa. We suggest that Li+ counterions forms a stronger network with the PBDT sulfonate groups off of the PBDT than the Na+ counterions. The smaller Li+ binds to the sulfonates on the PBDT chain more strongly, confirming that the modulus of this class of materials has ionic origins. We investigated the dielectric dynamics of cellulose in ILs through DRS to understand the fundamental properties of cellulose-IL solutions with varying cellulose concentration and IL. Like the MICs, the cellulose-IL solutions showed relatively high ionic conductivity compared to their respective neat IL, all within a factor of 4 at 30 °C at the highest cellulose concentration, as well as minimal increase in the dynamic DRS Tg (up to 10 °C). The ionic conductivity normalized by the DRS Tg show all data collapsing on a single curve with each IL suggesting that the glassy dynamics in these solutions is dictated by the ion arrangement produced on charge transport. Additionally, increasing the cellulose concentration increases the static dielectric constant relative to the neat ILs suggesting the association between the cellulose and IL ions enhances the polarizability of the solution over the neat IL.

Download or read book Investigations Into Ion Transport Properties of Polymerized Ionic Liquids and Related Materials written by Jordan Reynolds Keith and published by . This book was released on 2019 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt: The body of work on polymerized ionic liquids has been growing rapidly in recent years as researchers expand the synthesis space to achieve novel membrane materials with high conductivity, excellent mechanical stability, and high transference number. Despite progress in identifying specific new polymers and useful properties, there has been limited agreement over the mechanism for ion transport in these materials. It is essential that we resolve said mechanism for polymerized-ionic-liquid conduction, with the goal of streamlining future material design. Molecular dynamics is an excellent tool for analyzing local coordination behavior, ion-hopping pathways, and other phenomena of length- and time-scales that are currently inaccessible to direct experimental observation. Ion transport is seen to proceed via a "climbing the ladder" mechanism involving the formation and breaking of ion-association pairs with, on average, four polymerized ions from two polymer chains. This results in a link between ion-association lifetime and diffusivity for chemically similar polymerized ionic liquids, a feature that distinguishes polymerized ionic liquids from a broad class of polymer electrolytes and low fragility ionomers. This is also shown to be the case for a set of backbone-polymerized ionic liquids, when compared to a chemically similar pendent-polymerized ionic liquid. This is particularly interesting because the pendent architectural motif proves to have significantly higher reversibility of ion-hopping events. The application of design rules inspired by this research has already led to the experimental discovery of highly decoupled polymerized ionic liquids with excellent conductivity at ambient temperature. Parametric simulation studies of poly(vinylimidazolium) polymerized ionic liquids and counterion variants have revealed a decoupling of ion mobility from polymer segmental dynamics. Small counterions are generally more decoupled, but results show that size is not the sole arbiter. For this set of different chemical components, encompassed by the anionic study, ion-association relaxation time, rather than lifetime, was proven to better correlate with diffusivity. Similar physics is observed between polymerized ionic liquids and salt-doped polymerized zwitterions for the population of mobile ions whose polymerized counter-charge is located on the end of a monomeric pendant. However, the cage-relaxation timescale appears to correlate better with diffusivity for the opposite ion in such materials

Download or read book Charge Transport and Mechanical Property Study of High Mobility Conjugated Polymers written by Mingfei Xiao and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ion Mobility Studies of Functional Polymeric Materials for Fuel Cells and Lithium Ion Batteries written by Shilpi Sanghi and published by . This book was released on 2011 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: The research presented in this thesis focuses on developing new functional polymeric materials that can conduct ions, H, or OH− or Li. The motivation behind this work was to understand the similarities and/or differences in the structure property relationships between polymer membranes and the conductivity of H+ and OH− ions, and between polymer membranes and the anhydrous conductivity of H+ and Li+ ions. This understanding is critical to developing durable polymer membranes with high H+, OH− and Li+ ion conductivity for proton exchange membrane fuel cells (PEMFCs), alkaline anion exchange membrane fuel cells (AAEMFCs) and lithium ion batteries respectively. Chapter 1 describes the basic functioning of PEMFCs, AAEMFCs and lithium ion batteries, the challenges associated with each research topic, and the fundamental mechanisms of ion transport. The proton conducting properties of poly(4-vinyl-1H-1,2,3-triazole) were investigated on a macroscopic scale by impedance spectroscopy and microscopic scale by solid state MAS NMR. It was found that proton conductivity is independent of molecular weight of the polymer, but influenced by orders of magnitude by the presence of residual dimethylformamide. To improve the mechanical properties of otherwise liquid-like 1H-1,2,3-triazole functionalized polysiloxane homopolymers, hybrid inorganic-organic proton exchange membranes (PEMs) containing 1H-viii 1,2,3-triazole grafted alkoxy silanes were synthesized, using sol-gel chemistry. This method enabled self-supporting membranes having proton conductivity comparable to uncrosslinked homopolymers. One of the biggest challenges with AEMs for use in AAEMFCs is finding a cationic polyelectrolyte that is chemically stable at elevated temperatures in high pH environment. Novel triazolium ionic salts were developed, having greater chemical stability under alkaline conditions compared to existing imidazolium ionic salts. However, the chemical stability of triazolium cations was not sufficient for AAEMFC applications. Excellent chemical stability of (C5H5)2Co+ in 2 M NaOH at 80°C over 30 days was demonstrated and polymerizable vinyl functionalized cobaltocenium monomers were synthesized. This work paves the way for future development of AEMs containing cobaltocenium moieties to facilitate hydroxide ion transport. Polymers containing covalently attached cyclic carbonates were synthesized and doped with lithium triflate and their lithium ion conductivities were investigated. The findings highlight the importance of high charge carrier density and flexibility of the polymer matrix to achieve high lithium ion conductivity. These results are similar to the key factors influencing anhydrous proton transport.

Download or read book 2015 2016 Assessment of the Army Research Laboratory written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2017-03-31 with total page 235 pages. Available in PDF, EPUB and Kindle. Book excerpt: The National Academies of Sciences, Engineering, and Medicine's Army Research Laboratory Technical Assessment Board (ARLTAB) provides biennial assessments of the scientific and technical quality of the research, development, and analysis programs at the Army Research Laboratory (ARL), focusing on ballistics sciences, human sciences, information sciences, materials sciences, and mechanical sciences. This biennial report summarizes the findings of the ARLTAB from the reviews conducted by the panels in 2015 and 2016 and subsumes the 2015-2016 interim report.

Download or read book Postdoctoral Research Associateships written by and published by . This book was released on 1986 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Study of transport properties and structure of extended chain polymers written by R. Edward Barker (Jr) and published by . This book was released on 1985 with total page 564 pages. Available in PDF, EPUB and Kindle. Book excerpt: The broad objective of the work was to relate charge, heat, and mass transport in the Air Force's extended chain polymers (especially poly-para-phenylene benzobisthiazole PBT) to other electrical, thermal, mechanical nad microstructural properties of the polymers and also to compare these very unusual, highly anisotropic Air Force materials with other materials when it is scientifically relevant or when potential applications may be involved. Special techniques were developed for making transport-property determinations on samples in the form of thin fibers and small area films. Two types of miniature cells were developed in the study of PBT transport properties. A very promising area of the research relates to an anisotropic version of the Barker-Sharbaugh weak electrolyte model for ionic conduction in polymers. A new technique which has been termed the diffusion controlled-differential current (DCDC) method evolved from experiments related to the weak electrolyte model. This DCDC-technique looks promising as a new analytical tool. The results for PBT turned out to be especially interesting because the ratio of ionic conductivities parallel and perpendicular to the chain axis was very large (100,000 at 300 K) and temperature dependent (smaller ratio at a higher temperature). Special techniques for the thermal conductivity allowed the axial and perpendicular thermal conductivities to be determined.

Download or read book Structure function property Relationships in Conjugated Polyelectrolytes written by Andres Garcia and published by . This book was released on 2009 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt: The attractive optoelectronic and mechanical properties of conjugated polymers have lead to intense research in understanding of their semiconducting properties and application in various devices. The properties of conjugated polymers are highly dependent and sensitive to intra- and inter-polymer chain contacts and new methods to manipulate and control these solution and solid state interactions and optoelectronic properties are thus continually being pursued. Conjugated polyelectrolytes (CPEs) are a class of conjugated polymers containing ionic substituents in which polymer chain interactions are known to be influence by long-range electrostatic interactions, not feasible in non-ionic conjugated polymers. Although, CPEs have exhibit device improvement when incorporated in light emitting and photovoltaic devices, the optical and particularly charge carrier transport properties are not fully understood. In this dissertation the influence of the ionic substituents on both the optical and charge transport properties of CPEs are systematically investigated in pursue of constructing concrete structure-function-property relationships that can be use as guidelines for the future design of CPEs that have tailored properties and function.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 602 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1975 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Handbook Of Solid State Batteries And Capacitors written by M Z A Munshi and published by World Scientific. This book was released on 1995-05-11 with total page 739 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solid state power sources have developed remarkably in the last three decades owing to improvements in technology and a greater understanding of the underlying basic sciences. In particular, a greater impetus has recently been placed in developing and commercializing small, lightweight, and highly energetic solid state power sources driven by demands from portable consumer electronics, medical technology, sensors, and electric vehicles. This comprehensive handbook features contributions by forerunners in the field of solid state power source technology from universities, research organizations, and industry. It is directed at the physicist, chemist, materials scientist, electrochemist, electrical engineer, science students, battery and capacitor technologists, and evaluators of present and future generations of power sources, as a reference text providing state-of-the-art reviews on solid state battery and capacitor technologies, and also insights into likely future developments in the field. The volume covers a comprehensive series of articles that deal with the fundamental aspects and experimental aspects of solid state power sources, an in-depth discussion on the state of the various technologies, and applications of these technologies. A description of the recent developments on solid state capacitor technology, and a comprehensive list of references in each and every article will help the reader with an encyclopedia of hidden information. The organization of the material has been carefully divided into thirty-one chapters to ensure that the handbook is thoroughly comprehensive and authoritative on the subject for the reader.

Download or read book Designing Ion containing Polymers with Controlled Structure and Dynamics written by Joshua Enokida and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Ion-containing polymers are a unique class of materials for which strong electrostatic interactions dictate physical properties. By altering molecular parameters, such as the backbone chemical structure, the ion content, and the ion-pair identity, the structure and dynamics of these polymers can be altered. Further investigation of the molecular parameters that govern their structure-property relationships is critical for the future development of these polymeric materials. Particularly, the incorporation of ammonium-based counterions into these polymers offers a facile method to tune their electrostatic interactions and hydrophobicity. Applying this concept, a bulky dimethyloctylammonium (DMOA) counterion was used to modify the organic solubility of styrenesulfonate in order to facilitate its direct solution copolymerization with isoprene. With these poly(isoprene-ran-styrenesulfonate) (P(I-ran-SS)) copolymers the effect of ion content and the counterion identity on the structure and dynamics were evaluated. In the first project, poly(isoprene-ran-dimethyloctylammonium styrenesulfonate) (P(I-ran-DMOASS)) copolymers with high molecular weights and dimethyloctylammonium styrenesulfonate (DMOASS) compositions ranging between 8 and 40 mol% (30 - 77 wt%) were synthesized via nitroxide-mediated polymerization. Thermal and viscoelastic characterization revealed distinct behaviors for the low (30 - 51 wt%) and high (56 - 77 wt%) DMOASS content copolymers. Three structural regimes were identified: ion clusters (30 wt% DMOASS), continuous ionic phase (56 - 77 wt% DMOASS), and the coexistence of the two (42 - 51 wt% DMOASS). As DMOASS content increased, small angle X-ray scattering revealed a gradual transition from the characteristic ion cluster structure to a smaller, more regular backbone-backbone structure associated with a continuous ionic phase. The ion clusters acted as physical crosslinks and introduced additional elasticity into the low DMOASS content copolymer, while the continuous ionic phase showed restricted flow behavior and the disappearance of a definitive plateau modulus. Dynamic mechanical analysis revealed two distinct Tg's at intermediate DMOASS content, indicating the coexistence of both structures. In the second project, the role of counterion sterics on the structure and dynamics of a low glass transition temperature, amorphous P(I-ran-SS) at low ion contents (7 mol%) was investigated using a series of symmetric, tetraalkylammonium counterions with methyl (TMA), ethyl (TEA), propyl (TPA), and butyl (TBA) pendent groups in addition to a sodium cation control. A detailed analysis of the aggregate structure was achieved by fitting the X-ray scattering profiles with a modified hard sphere model. Increasing the counterion sterics from sodium to TEA resulted in slight changes to the aggregates with some ionic groups present in the isoprene matrix. For the more sterically hindered TPA and TBA counterions, considerable disruption of the structure occurs. Using solid-state NMR, dynamic mechanical analysis, and rheology, the effect of the counterion sterics on the copolymer dynamics was determined. The larger counterions exhibited an increase in the dynamic moduli at high frequency while decreasing the dynamic moduli at lower frequencies in addition to possessing faster molecular dynamics. These two observations correspond to the incorporation of more ionic groups into the isoprene matrix and weakening of the dipole-dipole interactions, respectively. Lastly, binary mixtures of TMA and TBA ammonium counterions were employed in these P(I-ran-SS) copolymers. The P(I-ran-SS) ionomers with TMA:TBA weight ratios of 100:0, 75:25, 50:50, 25:75, and 0:100 were prepared through solution blending. The SAXS profiles and Kinning-Thomas fitting showed only slight structural changes between 100:0 and 50:50, while major modification of the structure appears once the ratio reaches 75:25 and above. The alterations of the structure also indicated a mixed counterion aggregate structure. The linear viscoelastic characterization of the mixed counterion ionomers showed an increase in the polymer dynamics at low frequencies with increasing TBA weight percentages. Additionally, preliminary tensile tests were collected that showed increased mechanical properties with the stronger electrostatic interaction associated with TMA counterions. Thus, the structure and properties of these low Tg, amorphous ionomers can be specifically tuned by using multiple counterions. Through these studies, the role of both ion content and counterion identity on the structure and dynamics of low Tg, amorphous P(I-ran-SS) copolymers have been elucidated. Furthermore, ammonium-based cations have been shown to offer a versatile means to modify both the ion aggregate structure and interaction strength of an ionomer. Appropriate selection of the pendent groups and mixture of different counterions allow for the properties of the ionomer to be freely tuned.

Download or read book Polymer Science and Engineering written by National Research Council and published by National Academies Press. This book was released on 1994-01-01 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymers are used in everything from nylon stockings to commercial aircraft to artificial heart valves, and they have a key role in addressing international competitiveness and other national issues. Polymer Science and Engineering explores the universe of polymers, describing their properties and wide-ranging potential, and presents the state of the science, with a hard look at downward trends in research support. Leading experts offer findings, recommendations, and research directions. Lively vignettes provide snapshots of polymers in everyday applications. The volume includes an overview of the use of polymers in such fields as medicine and biotechnology, information and communication, housing and construction, energy and transportation, national defense, and environmental protection. The committee looks at the various classes of polymersâ€"plastics, fibers, composites, and other materials, as well as polymers used as membranes and coatingsâ€"and how their composition and specific methods of processing result in unparalleled usefulness. The reader can also learn the science behind the technology, including efforts to model polymer synthesis after nature's methods, and breakthroughs in characterizing polymer properties needed for twenty-first-century applications. This informative volume will be important to chemists, engineers, materials scientists, researchers, industrialists, and policymakers interested in the role of polymers, as well as to science and engineering educators and students.

Download or read book SRIM the Stopping and Range of Ions in Matter written by James F. Ziegler and published by Lulu.com. This book was released on 2008 with total page 683 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This is a textbook the gives the background of the stopping and range of ions in matter (www.SRIM.org). It is written to be the prime resource for those who use SRIM in scientific work."--Lulu.com.

Download or read book Energy Research Abstracts written by and published by . This book was released on 1994-12 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book U S Government Research Reports written by and published by . This book was released on 1963 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Electrode Materials for Energy Storage and Conversion written by Mesfin A. Kebede and published by CRC Press. This book was released on 2021-11-17 with total page 518 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive overview of the latest developments and materials used in electrochemical energy storage and conversion devices, including lithium-ion batteries, sodium-ion batteries, zinc-ion batteries, supercapacitors and conversion materials for solar and fuel cells. Chapters introduce the technologies behind each material, in addition to the fundamental principles of the devices, and their wider impact and contribution to the field. This book will be an ideal reference for researchers and individuals working in industries based on energy storage and conversion technologies across physics, chemistry and engineering. FEATURES Edited by established authorities, with chapter contributions from subject-area specialists Provides a comprehensive review of the field Up to date with the latest developments and research Editors Dr. Mesfin A. Kebede obtained his PhD in Metallurgical Engineering from Inha University, South Korea. He is now a principal research scientist at Energy Centre of Council for Scientific and Industrial Research (CSIR), South Africa. He was previously an assistant professor in the Department of Applied Physics and Materials Science at Hawassa University, Ethiopia. His extensive research experience covers the use of electrode materials for energy storage and energy conversion. Prof. Fabian I. Ezema is a professor at the University of Nigeria, Nsukka. He obtained his PhD in Physics and Astronomy from University of Nigeria, Nsukka. His research focuses on several areas of materials science with an emphasis on energy applications, specifically electrode materials for energy conversion and storage.