Dissertations / Theses on the topic 'Polyelectrolytes Conductivity'
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1
Lilley, Scott J. "Enhancing the conductivity of crystalline polymer electrolytes." Thesis, St Andrews, 2007. http://hdl.handle.net/10023/481.
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Wang, Shanshan. "Development of solid polymer electrolytes of polyurethane and polyether-modified polysiloxane blends with lithium salts." Akron, OH : University of Akron, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1196139638.
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Dissertation (Ph. D.)--University of Akron, Dept. of Polymer Engineering, 2007."December, 2007." Title from electronic dissertation title page (viewed 01/30/2008) Advisor, Kyonsuku Min; Committee members, Mark Soucek, Kevin A. Cavicchi, Gary R. Hamed, Michael H. Cheung; Department Chair, Sadhan C. Jana; Dean of the College, Stephen Z. D. Cheng; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
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Zapata, Pedro José. "High throughput study of fuel cell proton exchange membranes: poly(vinylidene fluoride)/acrylic polyelectrolyte blends and nanocomposites with zirconium." Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/33991.
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In view of the unfavorable panorama of actual energy supply practices, alternative sustainable energy sources and conversion approaches have acquired noteworthy significance in recent years. Among these, proton exchange membrane fuel cells (PEMFCs) are being considered as a pivotal building block in the transition towards a sustainable energy economy. The proton exchange membrane (PEM) is a vital component, as well as a performance-limiting factor, of the PEMFC. Consequently, the development of high performance PEM materials is of upmost importance for the advance of the PEMFC field. In this work, alternative PEM materials based on semi-interpenetrated networks from blends of poly(vinyledene fluoride) (PVDF) and sulfonated crosslinked acrylic polyelectrolytes (PE), as well as tri-phase PVDF/PE/zirconium-based composites, are studied. To alleviate the burden resulting from the vast number of possible combinations of the different precursors utilized in the preparation of the membranes, custom high throughput screening systems have been developed for their characterization. By coupling the data spaces obtained via these systems with the appropriate statistical and data analysis tools it was found that, despite not being directly involved in the proton transport process, the inert PVDF phase plays a major role on proton conductivity. Particularly, a univocal inverse correlation between the PVDF crystalline characteristics (i.e., crystallinity and crystallite size) and melt viscosity, and membrane proton conductivity was discovered. Membranes based on highly crystalline and viscous PVDF homopolymers exhibited reduced proton conductivity due to precluded segmental motion of the PE chains during crosslinking. In addition, a maximum effective amount of PE (55-60wt%) beneficial for proton conductivity was revealed. In the case of composite membranes, despite the fact that nanoparticle dispersion was thermodynamically limited, a general improvement in proton conductivity was evidenced at low to medium nanoparticle loadings (0.5 to 1wt%) in comparison to non-hybrid PVDF/PE references. This beneficial effect was particularly noticeable in membranes based on PVDF homopolymers (7% to 14.3% increment), where the nanoparticles induced a "healing" effect by providing proton-conducting paths between non-crosslinked PE channels separated by dense PVDF areas resulting from large PVDF crystallites. In general, the results presented herein are promising for the development of new cost-effective alternative PEMs.
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Bocharova, Vera. "Electrically Conductive Low Dimensional Nanostructures: Synthesis, Characterisation and Application." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1231161926227-23379.
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Miniaturization has become a driving force in different areas of technology including microelectronics, sensoric- and bio-technologies and in fundamental science. Because of the well-known limitations of conventional lithographic methods, newly emerging bottom-up approach, utilizing self-assembly of various nanoobjects including single polymer molecules and carbon nanotubes constitutes a very promising alternative for fabrication of ultimately small devices. Carbon nanotubes are attractive materials for nanotechnology and hold much promise to revolutionize fundamental science in a investigation of phenomena, associated with the nanometer–sized objects.It was found in this work that grafted chains of poly(2-vinylpyridine) form a shell covering the carbon nanotubes that makes them dispersible in organic solvents and in acidic water (CNTs-g-P2VP).The positively charged poly(2-vinylpyridine) shell is responsible for the selective deposition of carbon nanotubes onto oppositely charged surfaces. It was established that the deposition CNTs-g-P2VP from aqueous dispersions at low pH is an effective method to prepare ultra-thin films with a tunable density of carbon nanotubes.It was shown that poly(2-vinylpyridine) grafted to carbon nanotubes is a universal support for the immobilization of various nanoclusters at the carbon nanotube's surface. Prussian Blue nanoparticles were selectively attached to the surface of CNTs-g-P2VP.Conducting polymer nanowires are another very promising kind of nanomaterials that could be also suitable for applications in nanodevices and nanosensors. In this work was developed a simple method to control the conformation and orientation of single adsorbed polyelectrolyte molecules by co-deposition with octylamine. A simple chemical route to conductive polypyrrole nanowires by the grafting of polypyrrole from molecules of polystyrensulfonic acid was developed. The dc conductivity of individual polypyrrole nanowires approaches the conductivity of polypyrole in bulk.The conductivity can be described using variable-range hopping model.
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Bocharova, Vera. "Electrically Conductive Low Dimensional Nanostructures: Synthesis, Characterisation and Application." Doctoral thesis, Technische Universität Dresden, 2008. https://tud.qucosa.de/id/qucosa%3A23607.
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Miniaturization has become a driving force in different areas of technology including microelectronics, sensoric- and bio-technologies and in fundamental science. Because of the well-known limitations of conventional lithographic methods, newly emerging bottom-up approach, utilizing self-assembly of various nanoobjects including single polymer molecules and carbon nanotubes constitutes a very promising alternative for fabrication of ultimately small devices. Carbon nanotubes are attractive materials for nanotechnology and hold much promise to revolutionize fundamental science in a investigation of phenomena, associated with the nanometer–sized objects.It was found in this work that grafted chains of poly(2-vinylpyridine) form a shell covering the carbon nanotubes that makes them dispersible in organic solvents and in acidic water (CNTs-g-P2VP).The positively charged poly(2-vinylpyridine) shell is responsible for the selective deposition of carbon nanotubes onto oppositely charged surfaces. It was established that the deposition CNTs-g-P2VP from aqueous dispersions at low pH is an effective method to prepare ultra-thin films with a tunable density of carbon nanotubes.It was shown that poly(2-vinylpyridine) grafted to carbon nanotubes is a universal support for the immobilization of various nanoclusters at the carbon nanotube's surface. Prussian Blue nanoparticles were selectively attached to the surface of CNTs-g-P2VP.Conducting polymer nanowires are another very promising kind of nanomaterials that could be also suitable for applications in nanodevices and nanosensors. In this work was developed a simple method to control the conformation and orientation of single adsorbed polyelectrolyte molecules by co-deposition with octylamine. A simple chemical route to conductive polypyrrole nanowires by the grafting of polypyrrole from molecules of polystyrensulfonic acid was developed. The dc conductivity of individual polypyrrole nanowires approaches the conductivity of polypyrole in bulk.The conductivity can be described using variable-range hopping model.
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Lin, Chia-Hung, and 林家宏. "Ionic Conductivity and Electrochemical s Reactions of Rigid-Rod Solid Polyelectrolytes." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/38022107140773093720.
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碩士國立中山大學
材料科學研究所
91
ABSTRACT sPBI is a heterocyclic aromatic polymer assuming a para- catenated backbone yielding a rod-like configuration. Because of its rigidity, this rod-like molecule displays superior mechanical tenacity, thermo-oxidative stability, and solvent resistance. It is also the precursor of rigid-rod solid polyelectrolyte exhibiting high solubility and superior ionic conductivity. Isotropic solution were prepared by dissolving sPBI in distilled methanesulfonic acid containing 0.0, 0.989, 4.76, 9.09, 15.0, 20.0, 23.1 wt. % lithium ion of dopants of LiCF3SO3 or LiN(CF3SO2)2. The room-temperature DC conductivity of sPBI cast film doped with 15.0 wt. % LiN(CF3SO2)2 parallel (�翣|) and transverse (�粻) to the film surface was as large as 8.26×10-6 and 1.84×10-7 S/cm, respectively. The concentration of 15.0 wt. % lithium ion was considered to be the critical concentration; and LiN(CF3SO2)2 was the more effective dopant. Scanning electron microscopy micrograph of a cut edge of the film displayed a layered structure parallel to the film surfaces, thus the parallel DC conductivity (�翣|) was batter than the transverse DC conductivity (�粻) of the same film. Because the dissociation energy of lithium salt and the relation of temperature and conductivity, we proved that sPBI film had ionic conduction. We used cyclic voltammetry with non-blocking electrode and without auxiliary electrolyte to study the electrochemical reactions of the sPBI rigid-rod solid polyelectrolyte.
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Chen, Chien-Chang, and 陳建彰. "Chemical Synthesis and Ionic Conductivity of Water-Soluble Articulated Rigid-Rod Solid Polyelectrolytes." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/73559897782059643859.
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碩士國立中山大學
材料科學研究所
91
A water-soluble rigid-rod polyelectrolyte sPBI-PS(Li+) could be doped with LiI and cast as a freestanding film from aqueous solution showing a room-temperature in-plane DC conductivity (�������n) of 8.3╳10-3 S/cm. However, the cast film assumed an anisotropic microstructure due to nematic liquid-crystalline rigid-rod backbone leading to an out-of-the plane DC conductivity (����) which was three orders smaller than those of the ������, and severely limited its applications as a solid polyelectrolyte for thin-film battery. 2-Sulfo-terephthalic acid and 5-sulfo-isophthalic acid in ratios of 5：1, 15：1, 25：1, or 50：1 were synthesized via copolycondensation reaction making the rigid-rod backbone of sPBI-PS(Li+) become articulated. Further reaction with 1,3-propanesultone pendants, the rigid-rod polyelectrolyte was changed into a new water-soluble articulated rigid-rod polyelectrolyte a-sPBI-PS(Li+). Various analyses were applied to ascertain chemical structure and purities of synthesized monomers and polymers. The copolymer conductivity and intrinsic viscosity would decrease with increasing the articulation ratio. For a-sPBI-PS(Li+), LiClO4 was a better dopant, compared to LiI, to enhance conductivity. a-sPBI-PS(Li+) (25:1) doped LiI had a room-temperature conductivity as high as 4.7´10-3 S/cm. No layered structure was revealed by wide-angle X-ray scattering and scanning electron microscope. The cast thin-film thus had 3-dimensionally isotropic structure and electrical conductivity.
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Sun, Ju-Pin, and 孫如彬. "Chemical Synthesis and Ionic Conductivity of Water-SolubleRigid-Rod and Articulated Rigid-Rod Solid Polyelectrolytes." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/24000426847352258497.
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碩士國立中山大學
材料科學研究所
89
ABSTRACT A water-soluble rigid-rod polyelectrolyte sPBI-PS(Li+) could be doped with LiI and cast as a freestanding film from aqueous solution showing a room-temperature in-plane DC conductivity (s|| ) of 8.3╳10-3 S/cm. However, the cast film assumed an anisotropic microstructure due to preferential orientation of the rigid-rod backbone leading to an out-of-the plane DC conductivity (s^) which was three orders smaller than those of the s||, and severely limited its applications as a solid polyelectrolyte for thin-film battery. In addition to synthesizing rigid-rod polyelectrolyte sPBI-PS(Li+) for comparison, this study used 2-sulfo-terephthalic acid and isophthalic acid in ratios of 15：1, 25：1, or 50：1 for copolycondensation reaction making the rigid-rod backbone of sPBI-PS(Li+) become articulated. Further reaction with 1,3-propanesultone pendants, the rigid-rod polyelectrolyte was changed into a new water-soluble articulated rigid-rod polyelectrolyte A-sPBI-PS(Li+). Various analyses were applied to ascertain chemical structure, purities, thermal properties and molecular weight of synthesized monomers and polymers. Freestanding films of sPBI-PS(Li+) and A-sPBI-PS(Li+) were cast from aqueous solutions doped with LiI, LiBF4, or LiCF3SO3 for various concentrations up to 5 wt.%. Thin-film room-temperature s|| of sPBI-PS(Li+) could be 3.15´10-3 S/cm, and of A-sPBI-PS(Li+) could be 2.76´10-3 S/cm. X-ray scattering and electron microscopic results suggested that the sPBI-PS(Li+) cast film was in-plane isotropic but out-of-the plane anisotropic, and the A-sPBI-PS(Li+) cast film was three-dimensionally isotropic.
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Du, Yue-Lin, and 杜岳霖. "Chemical Synthesis and Ionic Conductivity of Water-Soluble Articulated Rigid-Rod Polyelectrolytes Derivatized with Sulfonated Ionomer Pendants." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/50733740246668114282.
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碩士國立中山大學
材料科學研究所
93
Articulated rigid-rod polymers asPBI were synthesized via polycondensation reaction. Using 2-sulfoterephthalic acid and 5-sulfoisophthalic acid in different ratios for copolycondensation reaction making the fully conjugated rigid-rod backbone became articulated. Both rigid-rod and articulated rigid-rod were further derivatized using alkane sulfonated pendants and became water-soluble rigid-rod and articulated rigid-rod polyelectrolytes. Lithium salt doped cast films of the polyelectrolytes showed a root-temperature DC conductivity parallel to film surface (
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Tsay, Pei-yun, and 蔡珮芸. "Chemical Synthesis and Ionic Conductivity of Water-Soluble Rigid-Rod Solid Polyelectrolytes with Aspect Ratio and Pendant Modifications." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/04523684329511900792.
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碩士國立中山大學
材料科學研究所
93
Polycondensation reaction was carried out for synthesizing rigid-rod polymer hPBI. Various molar ratios (50:1, 25:1, and 15:1) of 2-hydroterephthalic acid and 5-hydroisophthalic acid were also introduced in the synthesis for articulated rigid-rod polymer a-hPBI. The polymers were further derivatized with 1,3-propanesulton for pendants of lithium ionomer to become water soluble polyelectrolytes hPBI-PS(Li+) and a-hPBI-PS(Li+), respectively. Lithium salt doped cast film of the rigid-rod polyelectrolyte hPBI-PS(Li+) showed a room-temperature DC conductivity parallel to film surface as high as 4.02×10-3 S/cm. Molecular weight of the rigid-rod polyelectrolyte was low indicating a small molecular aspect ratio. In cast film, the molecules were randomly distributed and highly isotropic facilitated Li cations mobility for a high film conductivity. The conductivity was also insensitive to the anion of lithium salt. No apparent layered structure was revealed by scanning electron microscope suggesting that the cast films had near three-dimensionally isotropic structure and conductivity.
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Binesh, Nader. "NMR And Conductivity Investigations Of Certain Polymeric And Inorganic Fast Protonic Conductors." Thesis, 1997. http://etd.iisc.ernet.in/handle/2005/1828.
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Ezzeddine, Alaa. "Surface Modification of Carbon Nanotubes with Conjugated Polyelectrolytes: Fundamental Interactions and Applications in Composite Materials, Nanofibers, Electronics, and Photovoltaics." Diss., 2015. http://hdl.handle.net/10754/582475.
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Ever since their discovery, Carbon nanotubes (CNTs) have been renowned to be potential candidates for a variety of applications. Nevertheless, the difficulties accompanied with their dispersion and poor solubility in various solvents have hindered CNTs potential applications. As a result, studies have been developed to address the dispersion problem. The solution is in modifying the surfaces of the nanotubes covalently or non-covalently with a desired dispersant. Various materials have been employed for this purpose out of which polymers are the most common. Non-covalent functionalization of CNTs via polymer wrapping represents an attractive method to obtain a stable and homogenous CNTs dispersion. This method is able to change the surface properties of the nanotubes without destroying their intrinsic structure and preserving their properties.
This thesis explores and studies the surface modification and solublization of pristine single and multiwalled carbon nanotubes via a simple solution mixing technique through non-covalent interactions of CNTs with various anionic and cationic conjugated polyelectrolytes (CPEs). The work includes studying the interaction of various poly(phenylene ethynylene) electrolytes with MWCNTs and an imidazolium functionalized poly(3-hexylthiophene) with SWCNTs. Our work here focuses on the noncovalent modifications of carbon nanotubes using novel CPEs in order to use these resulting CPE/CNT complexes in various applications. Upon modifying the CNTs with the CPEs, the resulting CPE/CNT complex has been proven to be easily dispersed in various organic and aqueous solution with excellent homogeneity and stability for several months. This complex was then used as a nanofiller and was dispersed in another polymer matrix (poly(methyl methacrylate), PMMA). The PMMA/CPE/CNT composite materials were cast or electrospun depending on their desired application. The presence of the CPE modified CNTs in the polymer matrix has been proven to enhance the composites thermal, mechanical and electrical properties compared to pristine CNTs.
Various spectroscopic and microscopic techniques such as UV-vis, fluorescence, TEM, AFM and SEM were used to study and characterize the CPE/CNT complexes. Also, TGA, DSC and DMA were used to study the thermal and mechanical properties of the composite materials.
Our current work represents a fundamental study on the non-covalent interactions between CNTs and CPEs on one hand and gives a real life example on the CPE/CNT application in composite materials and electronics.
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Chen, Yun-Sheng, and 陳昀聖. "Chemical Synthesis and Ionic Conductivity of Water-Soluble Rigid-Rod Polyelectrolyte." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/87571283566328804510.
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碩士國立中山大學
材料科學研究所
89
Poly(p-phenylenebenzobisimidazole), PBI, is a rigid-rod polymer with a fully conjugated backbone having superior mechanical properties, thermo-oxi- dative and solvent stabilities. The stabilities cause processing difficulties and in terms limit its applications in critical technologies, such as conducting polymers, nonlinear optics, and solid polyelectrolytes. In this study, a chemical derivative of PBI, poly[1,7-dihydrobenzo[1,2- d:4,5-d’]diimidazo-2,6-diyl[2-(2-sulfo)-p-phenylene]], sPBI, was synthesized by polycondensation reaction of 1,2,4,5-tetraaminobenzene tetrahydrochloride with 2-sulfoterephthalic acid in poly(phosphoric acid). Isolated sPBI was measured in 30oC methanesulfonic acid for an intrinsic viscosity as high as 10.5 dL/g. sPBI polymer was then reacted with 1,3-propanesultone in dimethylsulfoxide containing sodium hydride for water-soluble rigid-rod polyelectrolyte, poly[1,7- dipropylsulfobenzo-[1,2-d:4,5-d’]diimidazo-2,6-diyl-[2,(2-sulfo)-p-phenylene]], sPBI-PS(Na+). sPBI-PS(Na+) was further converted to sPBI-PS(Li+) with hydrochloride and followed with lithium hydroxide. Various analyses were applied to ascertain chemical structure, purities and thermal properties of synthesized monomers and polymers. sPBI-PS(Li+) aqueous solutions were doped individually with lithium salts of LiI, LiBF4, and LiCF3SO3 at concentrations up to 1.7×10-5 wt./wt., which were cast into freestanding films of 10-25 μm in thickness. Direct-current conductivity measured at room- temperature parallel to the film surface was as large as 9.74×10-5 S/cm. The ionic nature of the conductivity was revealed by constant-voltage depletion measurements. X-ray scattering results suggested that the cast film was in-plane isotropic but out-of-the plane anisotropic with the rigid-rod backbone lying in the plane of the film.
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Yang, Szu-nang, and 楊思楠. "Studies on Molecular Configuration and Thermodynamic Behavior of Polyelectrolyte Solutions Based on their Conductivity Characterasitic." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/55918442071706617974.
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碩士國立臺灣大學
材料科學與工程學研究所
86
The main purpose of this research thesis is to explore the of the thermodynamics and transport characteristics of polyelectrolyte solutions. Generally, the behavior of polyelectrolyte solutions is affected by three main factors: 1. Viscosity effect (which includes the viscosity of the polyelectrolyte and the viscosity after salt is added). 2. Shape effects (the degree of difficulty of dispersion and migration). 3.The inter chain's and intra chain's electrostatic force. These three factors are not completely independent and then intricate interaction renders the thermodynamics of polyelectrolyte solutions different from other polymer solutions. A novel theories, based on the "Core shell Model" and "Coagulation Phenomena", was proposed to give an accurate perdiction on the scaling relationship of equivalent conductivity vs. concentration and molecular weight of polyelectrolytes. Description of the conformations of polyelectrolyte under different concentration was also provided. A reported conductivity data of Poly( sodium styrene sulfonate) [NaPSS] solutions with monodispersed molecular weight was choose to check the application of the theory. The conductivity and viscosity of Poly( sodium styrene sulfonate) [NaPSS] solution with multidispersed molecular weight were also measured and the results were employed to investigat the effect of multidispersity of molecular weight on the theoretical prediction.
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Yang, Si-Nan, and 楊思楠. "Studies on Molecular Configuration and Thermodynamic Behavior of Polyelectrolyte Solutions Based on their Conductivity Characterasitic." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/87135636568262959542.
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