Download or read book Design Synthesis and Characterization of Novel Materials with High Ionic Conductivity written by Xiangyun Wei and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Solid anhydrous proton conductors, with room temperature conductivity higher than 10--3 S/cm, were discovered in the mixtures of hydrogen sulfate and sulfate salts. These materials include Li2SO 4-LiHSO4, BeSO4-Be(HSO4)2 and Al2(SO4)3-Al(HSO4)3.

Download or read book Design Synthesis and Characterization of Novel Materials to Construct High energy density Rechargeable Cells written by Zheng Yue and published by . This book was released on 2018 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Design Synthesis and Characterization of Novel Materials for High performance Lithium sulfur Batteries written by Na Zhang and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: With ever-increasing energy demands, tremendous efforts have been devoted to developing rechargeable batteries. Conventional lithium-ion batteries have been widely used for decades, but are approaching their theoretical limit and are unable to meet the rising energy demands. Lithium–sulfur (Li–S) batteries are being actively pursued owing to their high energy density and cost-effectiveness. However, the commercial implementation of Li–S batteries has been impeded by the challenges associated with the sulfur cathodes, including extremely low conductivity, large volumetric expansion and rapid capacity loss arising from the dissolution of the intermediates, and the Li anode, owing to the uncontrollable formation of Li dendrites. To fulfill the promise of Li–S batteries as high-energy devices, it is necessary to solve these issues. In this dissertation, effective materials as sulfur hosts have been studied and possible strategies to improve the performance of the sulfur cathode proposed. These involve designing the structure of the host material to efficiently accommodate sulfur and, at the same time, applying the strong adsorption properties between the active material and the host. As to the Li anode, approaches to suppress the growth of Li dendrites were demonstrated by coating the surface of the anode current collector. These strategies were successful in inhibiting Li dendrites and significantly improve the performance of Li anodes. These studies provide promising results for high-performance Li–S batteries for future large-scale applications.

Download or read book The Design Synthesis and Characterization of Novel Electronic Organic Materials written by Wesley Thomas Walker and published by . This book was released on 2009 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Design Synthesis and Characterization of Novel Semiconducting Metal Chalcogenides with Multifunctional Properties written by and published by . This book was released on 2008 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal chalcogenides possess a wide range of interesting chemical and physical properties, including low-temperature superconductivity, semiconductivity, ionic conductivity, intercalation, and optical properties. To expand chalcogenides beyond their traditional applications, it is desirable to generate novel chalcogenide materials with multifunctionality for uses in the areas of catalysis, separation, ion exchange, and gas storage by modifying the framework architectures and tuning the chemical components. The primary focus of my Ph. D. study is to design and synthesize chalcogenide materials with new structures and interesting multifunctional properties. The large variety of chemical compositions and structures make it possible to tune the properties, such as band gap, luminescence, pore size, surface area, and thermal stability. Most of the synthesis has been carried out using solvothermal reactions refs in pyrex tube or teflon lined autoclaves. Novel three-dimensional (3D) microporous chalcogenides constructed on building units [M-Sn-Q]n- (M=Zn, Cd, Mn; Q=S, Se) have been obtained. Their structures have been characterized by both single crystal and powder X-ray diffraction methods. Optical diffuse reflectance experiments have indicated that these compounds are semiconductors with intermediate band gaps between 1.5~2.9eV. The successful doping/substitution of 5%~20% Mn and Se in the [Zn-Sn-S]n- structure allows systematic tuning of the band gap and optical properties of this semiconductor compound. All compounds show a high thermal stability over 400°C. Our studies also show that the guest molecules and cations residing in the open frameworks are exchangeable. Another novel two dimentional ion sulfide [Fe(en)3]·[Fe16S20]·en compound was synthesized as well. UV-Vis reflectance spectroscopy showed a very low absorption coefficient and small band gap ~0.5eV. Doping/substitution experiments with Co and Mn replacing Fe were carried out and the properties will be discussed. In summary, this work has provided examples of rational synthesis and property tuning of new functional materials with new structure types, and demonstrated structure-property correlation in metal chalcogenide based compounds. It has provided useful information for the future developments of material synthesis with desired multifunctionality.

Download or read book Design Synthesis and Application of Novel Conjugated Materials written by Haichang Zhang and published by Frontiers Media SA. This book was released on 2021-02-11 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 692 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Directory of Graduate Research written by American Chemical Society. Committee on Professional Training and published by . This book was released on 2005 with total page 1932 pages. Available in PDF, EPUB and Kindle. Book excerpt: Faculties, publications and doctoral theses in departments or divisions of chemistry, chemical engineering, biochemistry and pharmaceutical and/or medicinal chemistry at universities in the United States and Canada.

Download or read book Design Strategies for Improving Ionic Conductivity in Solid Polymer Electrolytes written by Yukyung Jung and published by . This book was released on 2015 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lithium-ion batteries are important in many aspects of modern life from portable electronics to electric vehicles. Their high specific energy, light weight, and design flexibility make them especially useful compared to other types of battery technologies. However, there remains room for improvement with regards to battery stability, safety, and increased capacity. One strategy for making lithium batteries both safer and more practical is by using solid polymer electrolytes (SPEs). Not only does the replacement of small molecule liquid electrolytes by SPEs significantly reduce the flammability of the battery, SPEs also make possible the construction of lighter weight batteries with increased flexibility in form factor. However, SPEs have not been widely incorporated into commercial batteries at the current time. Their applications are limited primarily due to their relatively low conductivities (~10-5 S/cm) at ambient temperatures. The first project describes the synthesis and characterization of a set of polyester-based polymer electrolytes. The polyesters were synthesized using transition metal-catalyzed alternating copolymerization of epoxides and anhydrides, which allowed the incorporation of a variety of Li+ ion coordinating functional groups including allyl ethers, pendant oligo(ethylene glycol), and esters. The bulk properties of the polymers and polymer-salt mixtures were investigated and compared to results from molecular dynamics (MD) simulations. The simulations were also used to probe the mechanism of Li + binding and transport in the polyesters. The simulations suggested that the relatively low Li + conductivity of the polyesters compared to PEO was most likely due to a lower than optimal density and spacing of the Li + binding sites in the polyesters. The insights from the polyester study were used to design a set of polyethers to further elucidate the source of PEO's unusually high ionic conductivity, as well as potentially improve the conductivity by further optimizing binding site connectivity. The polyethers were synthesized using acyclic diene metathesis (ADMET) polymerization, and a set of polymers was made with very specific and systematic alterations in structure. By studying the ionic conductivity as a function of temperature, we were able to analyze the effect of binding group density and pattern on the ionic conductivity and Li + ion transport mechanism in polyethers. The third project was inspired by the search for catalysts to develop novel high performance materials. Enantioselective [beta]-diiminate zinc catalysts were designed for the synthesis of highly isotactic polycarbonates from CO2 and meso epoxides. The ligand optimization process is described, as well as the characterization of the catalyst and isotactic poly(cyclohexene carbonate).

Download or read book Design Synthesis and Characterization of Novel Functional Rod like and Disc shaped Molecules written by Wenmiao Shu and published by . This book was released on 2001 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2008 with total page 994 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Design Synthesis Characterization and Application of Novel Processable Conducing Polymers written by Yaoliang Hong and published by . This book was released on 1996 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Design Synthesis and Characterization of Functional Materials for Battery Electrolyte and Marine Antifouling Applications written by Hilda Gail Buss and published by . This book was released on 2017 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, challenges associated with the creation of anti-fouling surfaces and polymer-based electrolytes are addressed using a versatile polymer chemistry that affords control over material functionality through the manipulation of the polymer's side chain composition. The polymers used in this thesis generally have a backbone comprised in-part or wholly of poly(ethylene oxide) (PEO) with pendant allyl side groups, to which various moieties can be attached using a straightforward thio-ene click. I describe the attachment of different side groups to design polymers with desirable properties, then characterize these polymers' performance when used as anti-fouling surface coatings and electrolytic solutions. The development of high lithium cation transference number electrolytes, those in which the ionic conductivity is carried predominantly by the lithium ion instead of its counteranion, could limit concentration polarization that plagues current battery electrolytes. The typical approach for achieving high transference number electrolytes is to immobilize the anion on a polymer to limit anion motion. We designed a lithium neutralized PEO backbone with pendent sulfonate groups to use as a dry single ion conductor. Interestingly, these sulfonate functionalized materials self-assembled into very well ordered, small (2.5nm) lamellae, which result from aggregation and phase segregation of the attached ions from the polymer backbone. Unfortunately, given that the ions are not solvated (i.e., dissociated) by the polymer backbone, no conductivity was observed in these materials, including at high (120°C) temperatures. The lack of ion dissociation suggests that a solvent with higher Lewis basicity or acidity than the PEO backbone is needed to disrupt the contact ion pairs and allow conductivity. Polyelectrolyte solutions were therefore prepared from the polyanion described above and a strong Lewis basic solvent, dimethyl sulfoxide. These solutions exhibited an excellent combination of high ionic conductivity and Li+ transference number (e.g., 1.2 mS/cm and 0.99, respectively, at 25°C). In addition, this system is tunable (polyanion molecular weight and charge concentration can be manipulated), and provided a platform to explore the tradeoff between conductivity and transference number in liquid electrolytes with an unprecedented combination of both. Taking advantage of this tunability, I explored the effect of temperature, polymer molecular weight, solvent choice, and small molecule salt addition on the solution transport properties. Li+ transference number was found to be temperature independent, as expected for solutions that are fully dissociated at all temperatures measured. Scaling theories for molecular weight dependence of diffusion coefficients described the polymer behavior well but did not capture the behavior of the lithium cation, which was generally found to be independent of polymer molecular weight. Solutions made in a variety of solvents all displayed high cation transference number and high conductivity, but there was no simple relationship between solvent and electrolyte properties. Finally, when mixed into the polyelectrolyte solution, small molecule salts, such as LiTFSI, increase the solution conductivity, but at a substantial cost to Li+ transference number. In another application, I designed polymer materials that prevent marine fouling, the attachment of organisms to human-made structures in marine environments. Amphiphilic polymers have been shown to be effective as antifouling materials against a variety of organisms and organic compounds. We therefore designed a polymer platform to present sequence-specific peptoids at the surface of thin film coatings. These amphiphilic coatings were used to study the effect of hydrophobic and hydrophilic residue sequence on antifouling performance. The polymer platform had a polystyrene (PS) anchoring block, and a PEO presentation block to which peptoids were attached. We showed that fluorinated moieties are very surface active and direct the surface composition of the polymer thin film. The position and number of fluorinated groups in the polypeptoid was shown to affect both the surface composition and antifouling properties of the film. Specifically, the position of the fluorinated units in the peptoid chain changes the surface chemistry and the antifouling behavior, while the number of fluorinated residues affects the fouling release properties. In addition to the peptoid sequence, the specific composition of the polymer platform is an important consideration for film stability and surface presentation. The anchoring block molecular weight plays an important role in film stability, but also affects the overall film hydrophobicity, which adversely affects antifouling performance. It was found that the coatings using an entirely hydrophobic scaffold, polystyrene-b-poly(dimethyl siloxane), performed well against only one of the marine organisms studied (Ulva linza), but that hydrophilic coatings comprised of polystyrene-b-poly(ethylene oxide) performed well against all marine organisms studied, including U. linza and Navicula. Finally, it was shown that perfluorooctane thiol attached directly to the polymer chain can direct surface presentation of the entire polymer system, thereby allowing improved anti-fouling film formation.

Download or read book The Design Synthesis and Characterization of Organic Functional Group Organization in Silica Via Imprinting written by John David Bass and published by . This book was released on 2005 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Electrically Conducting Organic Materials Design Synthesis and Characterization written by J. Bernstein and published by . This book was released on 1988 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: During this initial two month period of activity we have already made progress in our program to learn to design organic conducting materials. We are concentrating our efforts mainly, but not exclusively, on the D ... A ... D and A ... D ... A molecular motifs outlined in the original proposal. As noted in the original proposal the archetypal molecular unit 1 is potentially endowed with a number of properties which are considered to be necessary conditions for electrical conduction in organic charge-transfer complexes: the stoichiometric donor:acceptor (D:A) ratio is predesigned into the molecule; appropriate chemical variations in A and D may be employed to modify the degree of charge-transfer from D to A and to obtain the desired delocalized electronic state. In the framework of this program we have completed the synthesis of two additional members of the family (2), and crystals of sufficient quality for structure determination have been obtained for 2b and 2c.

Download or read book Design Synthesis and Characterization of Novel Lead free Multiferroic and Relaxor Materials written by Hsin Yu Wu and published by . This book was released on 2019 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: New multiferroic solid solutions of (1-x)BiFeO3-xBaHfO3 (BF-BaHf) with x = 0.05 - 0.95 has been prepared by conventional solid-state reaction in the form of ceramics. X-ray powder diffraction revealed that the perovskite structure of BF-BaHf transfers from rhombohedral to cubic symmetry with the increasing concentration of BaHf, resulting in the formation of solid solution. Compared with pure BF, the ferromagnetism in the BF-BaHf solid solution is substantially enhanced by the structural distortion due to A-and B-site co-substitutions, with remanent magnetization Mr = 0.0469 ????" ⁄????. ???? in x = 0.15. Meanwhile, ferroelectric domains were observed by transmission electron microscopy for x = 0.15. This confirms the beneficial role of BaHf substitution in enhancing magnetic properties while maintaining ferroelectric properties of the BF-based multiferroic materials. Another new multiferroic solid solution of pseudo-binary system (1-x)[0.8BiFeO3- 0.2BaHfO3]-xBaTiO3 [(1-x)(0.8BF-0.2BaHf)-xBaT] has been successfully synthesized by solid state reaction with x = 0.15 - 0.95. All the composition studies showed a gradual phase transition from rhombohedral to tetragonal phase as the BaT concentration increases. A morphotropic phase boundary is found in the composition range of 0.70

Download or read book Beyond the Molecular Frontier written by National Research Council and published by National Academies Press. This book was released on 2003-03-19 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemistry and chemical engineering have changed significantly in the last decade. They have broadened their scopeâ€"into biology, nanotechnology, materials science, computation, and advanced methods of process systems engineering and controlâ€"so much that the programs in most chemistry and chemical engineering departments now barely resemble the classical notion of chemistry. Beyond the Molecular Frontier brings together research, discovery, and invention across the entire spectrum of the chemical sciencesâ€"from fundamental, molecular-level chemistry to large-scale chemical processing technology. This reflects the way the field has evolved, the synergy at universities between research and education in chemistry and chemical engineering, and the way chemists and chemical engineers work together in industry. The astonishing developments in science and engineering during the 20th century have made it possible to dream of new goals that might previously have been considered unthinkable. This book identifies the key opportunities and challenges for the chemical sciences, from basic research to societal needs and from terrorism defense to environmental protection, and it looks at the ways in which chemists and chemical engineers can work together to contribute to an improved future.