Kliknij ten link, aby zobaczyć inne rodzaje publikacji na ten temat: POLYMER OXIDE.
Rozprawy doktorskie na temat „POLYMER OXIDE”
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 50 najlepszych rozpraw doktorskich naukowych na temat „POLYMER OXIDE”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj rozprawy doktorskie z różnych dziedzin i twórz odpowiednie bibliografie.
1
Wang, Yi. "The Synthesis and Characterization of Amphiphilic Poly(Ethylene Oxide)-Block-Poly(Octadecyl Acrylate) Block Copolymers". University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1399491109.
Pełny tekst źródła
2
Wang, Shiping. "THICKNESS AND CRYSTALLINITY DEPENDENT SWELLING OF POLY (ETHYLENE OXIDE) /POLY (METHYL METHACRYLATE) BLEND FILMS". University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1556831245474707.
Pełny tekst źródła
3
Ammar, Ali M. "REDUCTION OF GRAPHENE OXIDE USING MICROWAVE AND ITS EFFECT ON POLYMER NANOCOMPOSITES PROPERTIES". University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1533123263694685.
Pełny tekst źródła
4
Raja, Munira. "Metal-oxide-conjugated polymer interface properties for applications in polymer electronics". Thesis, University of Liverpool, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406832.
Pełny tekst źródła
5
Bhide, Mahesh. "Nitric oxide delivery from polymeric wound dressings". Akron, OH : University of Akron, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1144940498.
Pełny tekst źródłaStreszczenie:
Thesis (Ph. D.)--University of Akron, Dept. of Chemistry, 2006."May, 2006." Title from electronic dissertation title page (viewed 10/11/2006). Advisor, Daniel J. Smith; Committee members, Michael J. Taschner, Wiley J. Youngs, Kim C. Calvo, Darrell H. Reneker; Department Chair, Michael J. Taschner; Dean of the College, Ronald F. Levant; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
6
Cheng, Yen Theng. "Functional Polymer Templates for Metal Oxide Nanostructures". Thesis, The University of Sydney, 2022. https://hdl.handle.net/2123/29660.
Pełny tekst źródłaStreszczenie:
Functional nanostructured metal oxides have attracted tremendous attention in the last several decades owing to their superior semiconducting, catalytic, and electronic properties over their bulk counterparts. While bulk metal oxide materials are typically robust, nanostructured metal oxides have been proven to show enhanced performances due to higher surface-to-volume ratios and shorter ion or electron diffusion paths. The soft templating approaches in combination with controlled polymer syntheses are particularly intriguing as they allow new opportunities to tailor the morphology and composition of the metal oxide nanostructures. The present Thesis aimed to investigate the synthesis of functional polymeric templates using reversible deactivation radical polymerisations that enable facile electrostatic complexation between the polymer templates and the inorganic precursors to nanostructure metal oxides with well-defined morphologies. In the first research chapter, we demonstrated polymerisation-induced self-aseembly as a scalable and modular synthesis approach to yield mesoporous carbon-coated anatase TiO2 in worm-like and vesicular morphologies. We also showed that the worm-like and vesicular carbon-coated TiO2 are viable as anode materials for lithium-ion batteries. In the second research chapter, we utilised cellulose nanocrystal polymer bottlebrushes to construct mesoporous carbon-coated anatase TiO2 nanorods and studied their electrochemical performance as anode materials for lithium-ion batteries. In the last research chapter, we extended the templating approach from the second research chapter to form niobium-based oxides (Nb2O5 polymorphs and titanium niobium oxides).
7
Celik, Guler (bayrakli). "Microwave-assisted Simultaneous Novel Synthesis Of Poly(dibromophenylene Oxide)s, Poly(diiodophenylene Oxide)s (p), Conducting(cp) And/or Crosslinked (clp) And/or Radical Ion Polymers (rip)". Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608296/index.pdf.
Pełny tekst źródłaStreszczenie:
Microwave-assisted novel synthesis of poly(dibromophenylene oxide) or poly(diiodophenylene oxide) (P), conducting polymer (CP) and/or crosslinked polymer (CLP) and/or radical ion polymer (RIP) were achieved simultaneously from lithium, sodium or potassium 2,4,6-bromophenolate or sodium 2,4,6-iodophenolate in a very short time interval.
Polymerizations were carried out by constant microwave energy with different time intervals varying from 1 to 20 minor at constant time intervals with variation of microwave energy from 70 to 900 watt
or varying the water content from 0.5 to 5 ml at constant time intervals and microwave energy. Poly(dihalophenylene oxide) and radical ion polymers were characterized by FTIR (Fourier Transform Infrared), 1H-NMR (Proton Nuclear Magnetic Resonance), 13C-NMR (Carbon-13 Nuclear Magnetic Resonance), TGA/ FTIR (Thermal Gravimetric Analysis / Fourier Transform Infrared), DSC (Differential Scanning Calorimeter), SEM (Scanning Electron Microscope), ESR (Electron Spin Resonance), GPC (Gel Permeation Chromatography), UV-Vis (UV-Visible Spectroscopy), Light Scattering and Elemental Analysis. Conducting and crosslinked polymers were characterized by FTIR, TGA/ FTIR, DSC, SEM, ESR, XRD (Powder Diffraction X-Ray) and Elemental Analysis. The effects of heating time, microwave energy and water content on the percent conversion and the polymer synthesis were also investigated.
8
Couture, Lorraine. "Adsorption of polyethylene oxide on latex particles". Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59265.
Pełny tekst źródłaStreszczenie:
Layer thickness measurements are used to investigate polymer adsorption and possible conformations of adsorbed polymer.In a first step, photon correlation spectroscopy (PCS) is used to monitor the layer thickness at different ratios of polyethylene oxide (PEO) per polystyrene (PS) latex spheres. Comparison of the polymer concentration at which the equilibrium layer thickness was attained with the concentration where the adsorption isotherm reached its plateau leads to a proposed three step adsorption process. Kinetic studies of the layer thickness build-up also support this mechanism. Polymer polydispersity and the effect of anchored end groups on layer thickness are found to be in agreement with theoretical predictions.
In a second step, a rheological investigation of PEO coated polystyrene-butadiene (PSB) latex spheres was performed. The influence of coating on the second virial coefficient was determined. Comparison of the layer thickness as measured by viscosity and PCS shows the relative importance of the latex polydispersity for the two methods.
9
Rodier, Bradley J. "Modification of Graphene Oxide for Tailored Functionality". Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1515509392532651.
Pełny tekst źródła
10
Li, Wei. "Composite polymer/graphite/oxide electrode systems for supercapacitors". University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439309266.
Pełny tekst źródła
11
Owen, Steven Robert. "Antimony oxide compounds for flame retardant ABS polymer". Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/27210.
Pełny tekst źródłaStreszczenie:
Antimony trioxide (Sb2O3) is a common additive in flame retardant formulations and a study has been made to determine the effects of adding it alone, or with four commercial brominated materials (OBDPO, BTBPE, TBBA and PDBS80) to ABS polymer. The results focus upon mechanical, rheological, microscopical and flame retardant properties, and the effects of different Sb2O3 grades with average particle sizes ranging from 0.1 to 11.8 μm. The Sb2O3 was mainly studied up to 12 wt% loading in ABS, since this is considered to be the maximum level used in commercial flame retardant formulations.
12
Al-Bermany, Ehssan. "Polymer/graphene oxide nanocomposites : surface adsorption and interfaces". Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/18510/.
Pełny tekst źródła
13
Chen, Suelin Ph D. Massachusetts Institute of Technology. "Polymer-coated iron oxide nanoparticles for medical imaging". Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59004.
Pełny tekst źródłaStreszczenie:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2010.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 144-157).
One of the most versatile and safe materials used in medicine are polymer-coated iron oxide nanoparticles. This dissertation describes several formulations for in vivo imaging applications. The paramagnetic polymer-coated iron oxide nanoparticle aminoSPARK is used as a fluorescence-mediated tomography (FMT) imaging agent for stratification of prostate cancer tumors. This is achieved by conjugating it to a peptide that targets SPARC (secreted protein acidic rich in cysteine), a biomarker protein associated with aggressive forms of prostate cancer. Several types of polymer coatings for iron oxide nanoparticles have been systematically explored using a novel high-throughput screening technique to optimize coating chemistries and synthetic conditions to produce nanoparticles with maximum stability and ability to lower T2 contrast for MR imaging (R2, or relaxivity). Carboxymethyl dextran emerged from the screen as an ideal coating for superparamagnetic iron oxide nanoparticles. A commercially available, FDA-approved nanoparticle with similar surface chemistry, Feraheme, was chosen as a platform nanoparticle for further development. This work presents the first instance of chemical modification of Feraheme, making it more amenable to bioconjugation by converting its free carboxyl groups to free amine groups. This amine-functionalized Feraheme nanoparticle (amino-FH) is then used as a base nanoparticle to which various targeting and reporting functionalities can be added. A FH-based nanoparticle that can be used for cell loading is synthesized by covalently combining Feraheme with protamine, a pharmaceutical that also acts as a membrane translocating agent. A rhodamine-protamine conjugate is synthesized and then covalently bound to amino-FH using carbodiimide (CDI) chemistry. This results in a magnetofluorescent cell-labeling nanoparticle (ProRho-FH) that is readily taken up by mouse mesenchymal stem cells and U87 glioma cells. ProRho-FH can be used to non-invasively track cells for development and monitoring of cell-based therapies or for further investigation of biological mechanisms such as cell migration, tumor growth, and metastasis. This combination of two FDA-approved, commercially available materials to yield a superparamagnetic and fluorescent cell labeling nanoparticle is an excellent alternative to the recently discontinued Feridex. All polymer-coated iron oxide nanoparticles used in this dissertation were thoroughly characterized to fully understand their physicochemical and magnetic properties.
by Suelin Chen.
Ph.D.
14
Abushrida, Ahmed. "Formulation of novel polymer coated iron oxide nanoparticles". Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/12537/.
Pełny tekst źródłaStreszczenie:
The aim of this study was to investigate how to produce iron oxide nanoparticles, with the potential for long circulation times or the ability to preferentially reach particular tissues. The preparation of iron oxide nanoparticles was achieved using inorganic solution methods to prepare particles of small size using a narrow size distribution. The nanoparticles were coated with dextran and carboxymethyl dextran as reference materials using the same method as in the preparation of the iron oxide nanoparticles. This project investigated the use of the biodegradable polymer poly(glycerol adipate) (PGA) as a coating for iron oxide nanoparticles. PGA is already used in drug delivery systems and showed an ability to control the rate of release of the drug. PGA can be readily modified with pendant functional groups leading to modifications of the physicochemical properties of the polymer. It can also be readily modified to form copolymers with the hydrophilic polymer poly(ethylene glycol) (PEG). PGA 40% acylated with stearic acid (PGA 40%C18) and the PEGylated copolymer PEG–PGA 40%C18 were synthesised for this work. The formulation of coated iron oxide nanoparticles was investigated using PGA and modified PGA polymers. The coating process was optimised producing small coated nanoparticles were measured by TEM and the best sizes are (16 ± 5 nm with PGA while with, modified PGA is 23 ±7 nm and with PEG–PGA 40%C18 is 16 ± 4 in diameter). The PGA–IONPs were over-coated by incubation with albumin and Tween. The coated particles were characterised by DLS, zeta potential, and transmission electron microscopy. The colloidal stability of the various particle formulations was investigated using increasing salt concentrations. These demonstrated that PGA–coated nanoparticles were more stable than the existing dextran formulations, and that increased stability was obtained by overcoating with albumin or Tween. A further increase in stability was seen with PEG-PGA coated nanoparticles. The cellular uptake of the RBITC labelled nanoparticle formulations was studied on the C6 medulloblastoma cell line using monolayer and 3-D aggregate cultures using fluorescence microscopy, confocal microscopy, transmission electron microscopy (TEM) and flow cytometry. The results indicated that these particles were readily internalised in C6 cells, but with an unusual subcellular distribution. Uptake was dependent on both nanoparticle concentration and incubation time. The incubation of cells with internalised particles demonstrated that particles were metabolised and fluorescence was lost from cells over a period of 4–12 hours. TEM studies showed that, after 1 hour, nanoparticles were found in all subcellular compartments, but that the route of entry into cells could not be readily determined. Experiments using 3-D cell cultures demonstrated that nanoparticles were readily taken up into aggregates, with nanoparticles penetrating deep into the aggregates. Overall, these studies demonstrated novel formulations of iron oxide nanoparticles coated with well-defined biodegradable PGA polymer layers, which were stable against aggregation under physiological conditions. These formulations show promise for use in a variety of medical applications.
15
Sutherland, Courtney M. "Poly(Arylene) Ethers Prepared From Functionalized 3,5-Difluorotriphenylphosphine Oxide". Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1341862470.
Pełny tekst źródła
16
Xue, Siqi. "Organic-modifier-free pathways for the preparation of polymer-metal oxide nanocomposites". Diss., Connect to online resource - MSU authorized users, 2007.
Znajdź pełny tekst źródła
17
DI, FRANCO Francesco. "ELECTROCHEMICAL FABRICATION OF METAL/OXIDE/CONDUCTING POLYMER JUNCTIONS FOR ELECTRONIC DEVICES". Doctoral thesis, Università degli Studi di Palermo, 2014. http://hdl.handle.net/10447/91201.
Pełny tekst źródła
18
Más, Noelia Rapún. "New polymer-inorganic oxide hybrid films for optoelectronic devices". Thesis, University of Surrey, 2004. http://epubs.surrey.ac.uk/843214/.
Pełny tekst źródłaStreszczenie:
This thesis reports research into the development of metal oxide-polymer hybrids as novel materials for optoelectronic packaging. Transparent hybrids have been successfully achieved, the chemistry of the interaction between organic-inorganic phases in the hybrid has been studied and the optical and thermal properties are reported. Polyacrylate-silica hybrids have been synthesised in acidic media via the sol-gel process from TEOS and acrylate monomer to yield a sol which has been coated and cured using UV irradiation, resulting in transparent and semi-transparent films. Various acrylates have been used and organically modified alkoxysilanes have been introduced in order to obtain hybrids of type I and II with different properties. For the characterisation of these films 13C NMR, 29Si NMR, FTIR and Raman spectroscopies and scanning electron microscopy (SEM) have been used. Ellipsometry has been used to measure refractive indices, thickness and to estimate thermal expansion coefficients. Polyacrylate-silica hybrids have been expanded with the synthesis and characterisation of polyacrylate-titania and polyacrylate-hafhia, wherein the acrylate plays a dual role as a complexing agent and a polymerisable species. These hybrids lead to transparent films with higher refractive indices than polyacrylate-silica hybrids. Epoxy resins cured with anhydride and imidazole catalyst are also reported and the incorporation of titania and zirconia nanoparticles is explored. Good miscibility and transparency are found when zirconia nanoparticles modified by silane coupling agents are utilised. The modification of the nanoparticles is studied by means of FTIR, 29Si NMR and Raman spectroscopies while the modified epoxy resins are studied by FTIR and Raman spectroscopy and SEM. Thermal studies are carried out with differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). Finally, the polymerisation kinetics of the modified epoxy resins are reported.
19
Bin, Manaf Ishak. "Ceramers from aqueous polymer solutions of poly(ethylene oxide)". Thesis, Loughborough University, 2001. https://dspace.lboro.ac.uk/2134/36083.
Pełny tekst źródłaStreszczenie:
The combination of inorganic and organic components in single materials makes accessible an immense new area of materials science that has profound implications in the development of novel materials, exhibiting a wide range of multifunctional properties. The so-called "sol-gel" process is normally used for the production of an inorganic phase within an organic polymer or cross-linkable oligomers. When the domain size of such materials is reduced to nanometer levels and the phases are interconnected, the hybrid materials are usually called "ceramers". The systems considered in this work are based on a water-soluble polymer, poly(ethylene oxide) (PEO) and silica (SiO2) networks produce by the sol-gel method. The PEO precursor solution was prepared by dissolving the resin in water at room temperature. Tetraethoxysilane (TEOS) was used as the alkoxysilane precursor. Different types of alkoxysilane precursors were prepared, based on TEOS and silane coupling agent. The silica present in the hybrid system was formulated to be at 25%, 35% and 50% w/w.
20
Galpaya, Dilini. "Synthesis, characterization and applications of graphene oxide-polymer nanocomposites". Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/85062/12/85062%28thesis%29.pdf.
Pełny tekst źródłaStreszczenie:
Graphene has emerged as one of the most exciting materials of the 21st century due to its unique properties which have demonstrated great potential for applications in energy storage, flexible electronics and multifunctional composites. This thesis has established a new technique for investigating the structure-property relationship of graphene-polymer nanocomposites at micro and nanoscales. The outcomes can help gain a fundamental understanding of the toughening mechanism in these novel nanocomposites and benefit the development of broad graphene based materials and devices.
21
Ravirajan, Punniamoorthy. "Characterisation and optimisation of hybrid polymer/metal oxide photovoltaic devices". Thesis, Imperial College London, 2005. http://hdl.handle.net/10044/1/8682.
Pełny tekst źródła
22
Abdallah, Mohammad Raji AlGhazi. "Role of polymer entanglements in polyethylene oxide induced fines flocculation". Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=38140.
Pełny tekst źródłaStreszczenie:
On a papermaking machine, fines and colloids are retained in a paper sheet. The most important particle interactions are among particles having a high weight fraction and a short characteristic interaction time. Most of these interactions follow Langmuir kinetics, in which the flocculation efficiency is one of the important parameters. To enhance retention, many retention aids are available, one of which is neutral polyethylene oxide (PEO) used in combination of a phenolic cofactor (CF).In this work, a new model was derived in which all possible interactions were considered and assumed to follow Langmuir kinetics. Since fines are the main component in the headbox of mechanical grade furnishes, fines homo- and heteroflocculation with a PEO/CF retention aid were investigated in a circulating flow loop, and found to follow Langmuir kinetics. The small amount of fines deposited on the fibers was attributed to the large detachment rate in turbulent shear. The apparent difference in the deposition time and the half time of flocculation was attributed to difference in efficiency. Fines homoflocculation showed that fines are flocculated (without a retention aid) to various extents depending on shear, and that aggregates of flocs will form when a retention aid is added.
The PEO/CF flocculation efficiency was found to be a function of various parameters, i.e., aging of PEO solution, stirring intensity and time of stirring during dissolution, concentration at storage, shearing and dilution prior to injection. Optimum conditions were found for most parameters, and a critical shear intensity was determined. This PEO behavior was attributed to the extent of entanglements of PEO coils, which can be characterized prior to its addition to the flocculation vessel by a newly developed method. In this method, the pressure drop of a PEO solution passing through a capillary constriction was measured and correlated with its flocculation efficiency. Using the derived correlation, the flocculation efficiency can be estimated, and the relevant parameters can be controlled. Moreover, the salt effect on a PEO/CF system in a pulp was investigated. Salt was found to react with a CF causing a decrease in the flocculation efficiency. The effect of this reaction can be eliminated if PEO is added directly after CF addition.
23
Naghavi, N. "Development of nitric oxide eluting nanocomposite polymer for cardiovascular applications". Thesis, University College London (University of London), 2016. http://discovery.ucl.ac.uk/1502301/.
Pełny tekst źródłaStreszczenie:
Cardiovascular implants must resist thrombosis and intimal hyperplasia, but they are prone to such patency limiting conditions during graft implantation and prior to endothelialisation. Nitric oxide (NO) elution from healthy endothelium maintains haemostasis throughout the vasculature, and surgical devices that release NO are known as desirable treatment options. Polyhedral oligomeric silsesquioxane poly(carbonate-urea)urethane (POSS-PCU) nanocomposite polymer, developed in our laboratory, has already been fabricated in the form of bypass grafts, showing promising mechanical and biocompatible properties. NO donors have been passively incorporated within POSS-PCU; however, the study recognised a need for better donor retention and sustained NO release. Therefore, this thesis has focussed on utilising novel NO-eluting POSS-PCU bypass grafts with the aim to prepare materials that can release prolonged sustained levels of NO within physiological concentration range, with greater retention of the donor within the base polymer. Methods: POSS-PCU was functionalised with S-nitrosothiol NO donors using two modification methods including 1) covalent technique, and 2) using nanoparticles as delivery vehicles for NO donors. In addition, the importance of the analytical method for NO measurement was established through comparison of NO release from the grafts prepared via passive modification method using two different measurement techniques, which included amperometric and chemiluminescence. Each synthesis step in the preparation of NO-releasing polymer was extensively characterised and NO release properties studied. Finally, the biocompatibility of these materials was assessed. Results: It was established that chemiluminescence method detected NO at higher level than the amperometric technique. The two different synthesis methods resulted in the production of two types of nanocomposite polymer for the preparation of bypass grafts capable of NO release. Both modification techniques eliminated the problems associated with donor leaching observed with the non-covalently modified POSS-PCU. Incorporation of nanoparticles did not significantly change the elastic modulus of the original polymer, whereas covalently modified samples resulted in a significant change in the elastic modulus, as well as viscosity of POSS-PCU. Covalently modified grafts released NO at levels ranging from 1 – 24 pmol.cm-2 .min- 1 for a short time period of 6 h; however, the incorporation of different wt% of the nanoparticles into POSS-PCU resulted in higher flux of NO release which ranged from 2 to 85 pmol.cm-2 .min-1 for durations of 9 to 20 h. NO-releasing polymers showed less degree of clot formation and platelet adhesion/activation compared with the unmodified POSS-PCU, with nanoparticle conjugated samples showing greater anti-thrombogenic effects compared with the covalently modified samples. Conclusion: NO donor functionalisation within POSS-PCU enabled research on prolonging sustained NO release at physiologically relevant concentrations and enhanced the anti-thrombogenic properties of POSS-PCU. In addition, methods of determining NO level clearly demonstrated the relative difference between analysis techniques for case specific NO detection that can be applied to distinct experimental models associated with NO-eluting cardiovascular implants.
24
Alquraini, Zahra. "Highly Conductive Solid Polymer Electrolytes: Poly(ethylene oxide)/LITFSI Blends". DigitalCommons@Robert W. Woodruff Library, Atlanta University Center, 2018. http://digitalcommons.auctr.edu/cauetds/145.
Pełny tekst źródłaStreszczenie:
In this study, highly ionic conductive solid polymer electrolytes have been prepared by blending high molecular weight polyethylene oxide (PEO: MW 35,000 and 100,000) and bis(trifluoromethane)sulfonamide lithium (LiTFSI) salt. The ionic conductivities were determined for several compositions of the blends at different temperatures. A maximum ionic conductivity of 9.45 x 10-6 S cm-1 at 25 °C has been obtained for the blends containing PEO-35,000/LiTFSI at an ethylene oxide to lithium salt ratio (EO/Li+) of 5, whereas a maximum ionic conductivity 7.7 x 10-6 S cm-1 at 25 °C was observed for the PEO-100,000/LiTFSI blend at EO/Li+ mole ratio of 5. For all the blends, increasing the temperature resulted in enhanced ionic conductivity. Furthermore, addition of tris(pentafluorophenyl)borane (TPFB) increased the conductivities at 25 oC. The overall conclusion of the study is that using LiTFSI and the TPFB in the blends results in ionic conductivities suitable for use in Li-air and/or Li-ion batteries.
25
Jaggernauth, Aneeta. "Polymer funcionalization of nano-graphene oxide by molecular layer deposition". Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/14832.
Pełny tekst źródłaStreszczenie:
Mestrado em Engenharia de MateriaisO presente trabalho aborda o processo de funcionalização por via seca de nanopartículas de óxido de grafeno (nano-GO) visando o estabelecimento de ligações a polietilenoglicol (PEG) na sua superfície. Atualmente utilizam-se métodos químicos de funcionalização por via húmida com esta finalidade, no entanto são demorados e resultam em perdas significativas de amostra. O trabalho foi realizado em duas fases: o GO foi primeiramente sintetizado em forma de filme e pó utilizando um método “Hummers” modificado, sendo caracterizado por FTIR, SEM e DLS; em seguida o GO foi exposto aos precursores do PEG num reator de deposição por camada molecular (MLD) sob condições de vácuo. Utilizaram-se temperaturas diversas de deposição, tendo-se observado uma adsorção ótima entre 90-100° C. Primeiramente, a deposição de PEG em pó de GO, com terminações de amina, confirmou por FTIR a presença dos picos característicos de PEG, aproximadamente aos 2925 cm-1 e 2850 cm-1, corroborando a funcionalização a seco do GO por um mecanismo de vaporização-condensação. A via MLD, usando TMA e EG como precursores foi então realizada no pó de GO, tendo proporcionado uma camada de passivação inicial rica em alumínio, na qual ciclos subsequentes de exposição ao monómero EG resultaram na sua adsorção e polimerização, tal como demonstrado por FTIR e análises EDS. O nano-GO-PEG é vantajoso para aplicações na área da biomedicina, incluindo sistemas de administração de fármacos, biossensores e terapia fototérmica. O PEG permite ao nano-GO ser reconhecido como biocompatível, estabelecendo uma superfície repelente e incrementando o transporte citoplasmático, permitindo assim características essenciais, tais como alta absorvância óptica, fluorescência e estabilidade em meio fisiológico, essenciais para os sistemas biológicos. O sucesso da produção do nano-GO funcionalizado com PEG pela via a seco aqui proposta poderá será favorável para outros tipos de funcionalização e copolimerização de nanopartículas.
This research aims to achieve a dry functionalization approach for covalently attaching polyethylene glycol (PEG) onto the surface of nano-graphene oxide (GO). Currently, wet chemical methods are used to achieve this, being characteristically time consuming and resulting in significant loss of sample. This work is carried out in two stages; GO is first synthesized using a modified Hummers’ method, and then characterized by FTIR, SEM and DLS; it is then produced in film and powder form, for exposure to precursors in an MLD reactor under rough vacuum conditions. GO films were exposed to PEG at variable temperatures, determining that at 90oC and 100oC the optimal adsorption occurred. Deposition of amine-terminated PEG on GO powder confirmed the presence of characteristic PEG peaks around 2925cm-1 and 2850cm-1 via FTIR, substantiating the dry functionalization of GO via vaporization-condensation. An MLD route, using TMA and EG precursors was then performed on GO powder, delivering an initial passivation layer of Al, onto which subsequent cycles of EG adsorbs, demonstrated by FTIR and EDS analysis. PEGylated-nano-GO is advantageous for applications in the area of biomedicine; including drug delivery systems, biosensors and photothermal therapy. PEG permits nano-GO to be recognized as biocompatible; establishing on it a non-fouling surface and increasing its cytoplasmic transport, thereby allowing its inherent characteristics such as high optical absorbance, fluorescence, and stability in physiological media to be pertinent to biological systems. Successful production of PEG functionalized nano-GO via the proposed method will be favourable for other possibilities of nanoparticle surface functionalization and copolymerization.
26
Yu, Kui 1967. "Multiple morphologies of polystyrene-b-poly(ethylene oxide) diblock copolymers in dilute solution". Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36076.
Pełny tekst źródłaStreszczenie:
Multiple morphologies of self-assembled aggregates of polystyrene- b-poly(ethylene oxide) (PS-b-PEO) diblock copolymers in dilute solution have been studied. The PS blocks are relatively long compared to the PEO blocks. The aggregates are prepared by the addition of water or methanol to the copolymer solutions in N,N-dimethylformamide (DMF), dioxane, or tetrahydrofuran (THF) to induce the aggregation of the PS blocks. Aqueous solutions of the aggregates are obtained by dialysis with water. Morphologies are directly studied by transmission electron microscopy (TEM).The morphogenic effect of the copolymer composition indicates that as the EO content in the diblock decreases, the morphology of the self-assembled aggregates changes progressively through spheres, rods, bilayers, and ultimately to inverted aggregates. The observed bilayers include lamellae, vesicles, tubules and large compound vesicles (LCVs), and the inverted aggregates include inverted (hollow) hoops with a hexagonal array and large compound micelles (LCMs).
The morphological transition from vesicles to inverted hoops is investigated, and a three-step mechanism is proposed. This mechanism involves a thickening of the vesicle walls accompanied by the formation of the hollow rods in the walls, and a decrease in the size of the original water core. Possible mechanisms of the formation of large vesicles from lamellae, as well as tubules and LCVs from vesicles are discussed.
The formation of the self-assembled aggregates with various morphologies is believed to be mainly controlled by the balance of three interactions arising from the core, the corona, and the core-solvent interface. Any factors, such as the addition of salt, which affect the balance will cause morphological changes. Accordingly, the morphogenic effects of added electrolytes, temperature, the common solvent, and the precipitant are studied. The study shows that various morphologies can be prepared from one diblock copolymer.
27
Yin, Wenbin. "Transient Studies of Electrochemical Reactions in Solid Oxide Fuel Cells and Li-ion Batteries". University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1521121469667941.
Pełny tekst źródła
28
Cerezo, Frances Therese, i francestherese_cerezo@hotmail com. "Thermal stability and mechanical property of polymer layered graphite oxide composites". RMIT University. Applied Sciences, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080627.161157.
Pełny tekst źródłaStreszczenie:
Polymer composites formed from layered fillers with high surface volume ratio show enhanced reinforcement. Graphite oxide is a high modulus material that can be separated into thin layers with high surface area. The aim of this study is to prepare polymer layered graphite oxide composites using functionalised polyolefin to enhance compatibility with various forms of layered graphite oxide in varying concentration. Functionalised polyolefins reinforced with layered graphite oxides and expanded graphite oxides were prepared using solution blending and melt blending methods. Three different mixing methods with varying shear intensity were employed to prepare polymer layered graphite oxide composites. The crystalline structure, thermal and mechanical properties of the prepared polymer layered graphite oxide composites was studied. Oxidised graphite prepared from the Staudenmaier method and its exfoliated form were dispersed in poly(ethylene-co-methyl acrylate-co-acrylic acid) (EMAA) via solution blending to prepare EMAA layered composites. The thermal stability was determined using thermogravimetric analysis. The EMAA layered composites showed higher thermal stability in comparison with pure EMAA. The mechanical properties of these EMAA layered composites were determined through dynamic mechanical analysis. Shear modulus, yield stress and storage modulus of EMAA in the presence of graphite oxide fillers decreased. A solution blending method was used to prepare poly(propylene-grafted-maleic anhydride) layered expanded graphite oxide composites (PPMA-EGO). Two types of PPMA-EGO were prepared using different mixing methods - low and high shear were employed. The effects of preparative mixing methods on the PPMA-EGO properties were investigated. The mechanical properties of PPMA-EGO obtained from dynamic mechanical analysis indicated that EGO had a reinforcing effect on the elastic behaviour of PPMA-EGO. This is due to strong interfacial adhesion between PPMA and EGO as a result of hydrogen bonding. The elastic behaviour of PPMA-EGO was affected by the surface area of graphite flakes. Low sheared PPMA-EGO elastic behaviour was found to be higher compared with that of high sheared PPMA-EGO. A melt blending method was used to prepare PPMA-EGO with varying EGO concentration. The interconnected network structure of EGO in the PPMA-EGO was not observed as shown by its scanning electron microscopy images. Thermogravimetric analysis of PPMA-EGO indicates increased decomposition temperature of the PPMA matrix. Dynamic mechanical analysis showed enhanced storage modulus of PPMA-EGO. The maximum elastic modulus of PPMA-EGO was observed at 3 %wt of EGO. The electrical conductivity of PPMA-EGO was measured only for EGO concentrations above 2 %wt. The EGO concentration was found to be the most critical factor in the enhancement of the electrical conductivity of PPMA-EGO. Wide angle X-ray diffraction analysis of all polymer layered graphite oxide composites revealed no change in interlayer spacing of graphite layers, indicating the absence of EMAA intercalation in the graphite layers. The crystallisation temperature and crystallinity of all polymer layered graphite oxide composites were determined using differential scanning calorimetry. The results indicated that graphite oxide and expanded graphite oxides acted as nucleating agents in inducing the crystallisation of functionalised polyolefin in the layered composites. However, the degree of crystallinity of functionalised polyolefin decreased in the layered composites.
29
McAlduff, Michael. "Solid-state NMR studies of polymer adsorption onto metal oxide surfaces". Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115692.
Pełny tekst źródłaStreszczenie:
This dissertation presents solid-state NMR studies that probe the dynamic and conformational properties of polymers adsorbed on solid surfaces in the dry state. The systems studied include a series of ethylene based random copolymers where the binding group is modified, and two diblock copolymer systems where the blocks have different intrinsic mobilities and surface interactions. The thesis begins by looking at the structures formed by the adsorption of poly (ethylene-co-acrylic acid) (PEA), poly (ethylene- co-vinyl alcohol) (EVOH), poly (ethylene-co-vinyl acetate) (EVA), and polyethylene (PE) on metal oxide powders (zirconia and alumina). NMR spectroscopy, FTIR-PAS, and TGA were used to characterize the surface behaviour of the systems with comparisons made between the bulk and adsorbed copolymers. 13C CPMAS, 1H and T 1 relaxation measurements were all recorded with the aim of correlating the microscopic structure of the surface with changes in NMR data. The chain conformation of adsorbed ethylene copolymers was found to strongly depend on the binding strength of the polar sticker groups with the substrates.The chain dynamics of adsorbed diblock copolymers in the dry state are reported for the first time. Poly (styrene)-b-poly ( t-butyl acrylate) (PS-PtButA) and poly (styrene)-b-poly (acrylic acid) (PS-PAA) were selected to vary both the block size and the binding strength. Once again the primary surface characterization methods are NMR spectroscopy, FTIR-PAS, and TGA. 13C CPMAS, 1H, T1, and T1rho relaxation measurements were all recorded with the aim of correlating the surface structures with changes in NMR data. For the most part, the observed trends in the chain mobilities of the anchor (PAA) and buoy (PS) blocks with block size can be correlated with the predicted mushroom, intermediate and extended brush structures which collapse upon removal of the solvent. However, the chain mobility of the PS buoys decreases with increasing anchor block size. Although the chain mobility of the PS buoys are moderately enhanced relative to the bulk state, the mobility is sufficiently restricted to comfirm the picture of a thin glassy layer with adhesive properties similar to the surface of bulk polystyrene.
The diblock copolymers poly (2-vinylpyridine), poly (isoprene)- b-poly (2--vinylpyridine), (PI-P2VP) and poly (isoprene)- b-poly (4-vinylpyridine) (PI-P4VP) were selected to complement the PS-PAA system as both systems have been studied by surface force microscopy. The large contrast in chain mobilities of the PI and PVP blocks allowed spectral editing through variation of the 13C cross polarization parameters. The trends in mobility with block size differ from that of PS-PAA in that the segmental mobility of the buoys increases with anchor block size as expected. The chain mobility of the collapsed PI brushes is significantly enhanced as compared to the bulk state, again supporting the interpretation of surface microscopy studies which require an entropically unfavorable flattened, yet rubbery, surface structure.
30
Livingstone, Veronica Jean. "One-Pot In-Situ Synthesis of Conductive Polymer/Metal Oxide Composites". University of Toledo / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=toledo158860469194691.
Pełny tekst źródła
31
Li, Zhehui. "Barium Oxide as an Intermediate Layer for Polymer Tandem Solar Cell". University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1365975150.
Pełny tekst źródła
32
Tokmoldin, Nurlan. "Fabrication and characterization of hybrid metal-oxide/polymer light-emitting diodes". Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/6327.
Pełny tekst źródłaStreszczenie:
Hybrid metal-oxide/polymer light-emitting diodes (HyLEDs) are a novel class of electronic devices based on a combination of electroluminescent organic and charge-injecting metal-oxide components. These devices employ air-stable electrodes, such as ITO and Au, and are therefore well suited for fabrication of encapsulation-free light-emitting devices. The current work is intended to provide an insight into operating mechanisms and limitations of the HyLEDs, and, on the basis of this knowledge, aims at modifying the device architecture in order to improve the performance. The choice of optically transparent metal-oxide charge-injection layers appears to be critical in this respect in order to optimize the electron-hole balance within the polymer layer. Starting from the original device architecture, ITO/TiO2/F8BT/MoO3/Au, which uses ITO as a cathode and Au as an anode, we follow different approaches, such as the use of dipolar self-assembled monolayers and nanoscale structuring of the electron-injecting interface, pursuing the goal of enhancing electron injection into the emissive layer. However, substitution of the electron-injecting layer of TiO2 with ZrO2 is demonstrated to be the most efficient of the approaches employed herein. Further, optimization of the device utilizing the latter metal oxide is demonstrated in terms of deposition and post-deposition treatment of the electron-injecting and electroluminescent layers. Substrate temperature during spray pyrolysis deposition of the electron-injecting layer is found to have a strong influence on the HyLED performance, as well as the precursor solution spraying rate and the layer thickness. On the other hand, post-deposition annealing of the polymer layer is shown to improve the device efficiency and brightness significantly, possible explanations lying in enhancement in polymer luminescence efficiency and formation of a more intimate contact between the electron-injecting and the active polymer layers. Combining electron-transporting (TiO2 and ZnO) and hole-blocking (Al2O3 and ZrO2) materials into a single electron-injecting layer is demonstrated to be an effective strategy of enhancing efficiency in the HyLEDs. The search for a hole-injecting electrode alternative to the conventionally used MoO3/Au leads to the device employing the PEDOT:PSS/VPP-PEDOT system, which though resulting in a poorer device efficiency, provides route for fabrication of vacuum deposition-free organic light-emitting devices. Finally, the HyLED architecture is demonstrated to offer better stability than the conventional architecture using LiF/Al as a cathode. It is hoped that the current work provides a better understanding of the requirements for fabrication of encapsulation-free organic light-emitting devices.
33
Ainsworth, David A. "Crystalline polymer and small molecule electrolytes". Thesis, University of St Andrews, 2010. http://hdl.handle.net/10023/2156.
Pełny tekst źródłaStreszczenie:
The research presented in this thesis includes a detailed investigation into factors influencing ionic conductivity in the crystalline polymer electrolyte PEO₆:LiPF₆. It has previously been shown that preparing PEO₆:LiPF₆ with PEO modified with larger –OC₂H₅ end groups increases ionic conductivity by one order of magnitude [¹],primarily due to disruption of the crystal structure caused by the inclusion of the larger end groups. In this study it is shown that by reducing PEO molecular weight in crystalline PEO₆:LiPF₆ ionic conductivity is also increased. This was attributed to an increasing concentration of polymer chain end regions upon lowering molecular weight resulting in the creation of more defects, as well as possible increases in crystallite size resulting in longer continuous pathways for ion transport. Similar results were observed using both polydispersed and monodispersed PEO to prepare complexes. In addition, it is demonstrated here that ionic conductivity in crystalline polymerelectrolytes is not confined to PEO₆:LiXF₆ (X=P, As, Sb)[²][³] type materials. The structures and ionic conductivity data are reported for a series of new crystalline polymer complexes: the alkali metal electrolytes. They are composed of low molecular weight PEO and different alkali metal hexafluoro salts (Na⁺, K⁺ and Rb⁺), and include the best conductor poly(ethylene oxide)₈:NaAsF₆ discovered to date [⁴], with a conductivity 1.5 orders of magnitude higher than poly(ethylene oxide)₆:LiAsF₆. A new class of solid ion conductor is reported: the crystalline small-molecule electrolytes. Such materials consist of lithium salts dissolved in low molecular weight glyme molecules [CH₃O(CH₂CH₂O)[subscript(n)]CH₃, n=1-12], forming crystalline complexes [⁵][⁶]. These materials are soft solids unlike ceramic electrolytes and unlike polymer electrolytes they are highly crystalline, are of low molecular weight and have no polydispersity. By varying the number of repeat units in the glyme molecule, many complexes may be prepared with a wide variety of structures. Here, ionic conductivity and cation transference number (t₊) data for several such complexes is presented [⁷][⁸][⁹].These complexes have appreciable ionic conductivities for crystalline complexes and their t₊ values vary markedly depending on the glyme molecule utilized. The differences in t₊ values can be directly attributed to differences in their crystal structures. [¹] Staunton, E., Andreev, Y.G. & Bruce, P.G. Factors influencing the conductivity of crystalline polymer electrolytes. Faraday Discussions 134, 143-156 (2007). [²] Gadjourova, Z., Andreev, Y.G., Tunstall, D.P. & Bruce, P.G. Ionic conductivity in crystalline polymer electrolytes. Nature 412, 6846 (2001). [³] Stoeva, Z., Martin-Litas, I., Staunton, I., Andreev, Y.G. & Bruce, B.G. Ionic Conductivity in the Crystalline Polymer Electrolytes PEO₆:LiXF₆, X = P, As, Sb. J. Am. Chem. Soc. 125, 4619-4626(2003). [⁴] Zhang, C., Gamble, S., Ainsworth, D., Slawin, A.M.Z., Andreev, Y.G. & Bruce, P.G. Alkali metal crystalline polymer electrolytes. Nature Materials 8, 580-584 (2009). [⁵] Henderson, W.A., Brooks, N.R., Brennessel, W.W. & Young Jr, V.G. Triglyme-Li⁺ Cation Solvate Structures: Models for Amorphous Concentrated Liquid and Polymer Electrolytes (I). Chem. Mater. 15, 4679-4684 (2003). [⁶] Henderson, W.A., Brooks, N.R. & Young Jr, V.G. Tetraglyme-Li⁺ Cation Solvate Structures: Models for Amorphous Concentrated Liquid and Polymer Electrolytes (II). Chem. Mater. 15, 4685-4690 (2003). [⁷] Zhang, C., Andreev, Y.G. & Bruce, P.G. Crystalline small-molecule electrolytes. Angewandte Chemie, International Edition 46, 2848-2850 (2007). [⁸] Zhang, C., Ainsworth, D., Andreev, Y.G. & Bruce, P.G. Ionic Conductivity in the Solid Glyme Complexes [CH₃O(CH₂CH₂O)[subscript(n)]CH₃]:LiAsF₆ (n = 3,4). J. Am. Chem. Soc. 129, 8700- 8701 (2007). [⁹] Zhang, C., Lilley, S.J., Ainsworth, D., Staunton, E., Andreev, Y.G., Slawin, A.M.Z. & Bruce, P.G. Structure and Conductivity of Small-Molecule Electrolytes [CH₃O(CH₂CH₂O)[subscript(n)]CH₃]:LiAsF₆ (n = 8-12). Chem. Mater. 20, 4039-4044 (2008).
34
Polverari, Marco. "Dynamic and evanescent wave light scattering of poly(ethylene oxide) - latex systems". Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28515.
Pełny tekst źródłaStreszczenie:
The principal aims of the thesis were to carry out a systematic analytical study to determine the solution properties of narrow-distribution and broad-distribution linear poly(ethylene oxide) (PEO) polymer samples in aqueous and organic solution and to study the adsorption properties of these polymer samples onto glass interfaces and spherical latex particles. The deposition characteristics of various types of bare and PEO coated latex particles onto collector surfaces were also studied.These studies allowed to ascertain the presence of PEO clusters in aqueous solution. The cluster size was found to be time dependent and to vary between 0.45 $ mu$m and 0.90 $ mu$m. The clusters were found to be in a thermodynamic equilibrium with the free polymer in solution and were found to reform spontaneously after a 30 minute period following filtration.
Adsorption studies indicated that the adsorption of PEO onto latex particles is kinetically controlled and that increased surface roughness and polarity of the latex particles decreases PEO adsorption. PEO clusters in solution were found to increase the value of the effective diffusion constant, D$ rm sb{eff}$ and thus decrease the calculated hydrodynamic layer thickness.
Evanescent wave light scattering was used in conjunction with a hydrodynamic impinging jet method for the study of depositing and non-depositing colloidal systems near interfaces. For non-depositing systems a comparison of the measured particle concentration profiles to the theoretically expected particle concentration profiles, calculated from DLVO theory, was made. The agreement was found to be very good.
The deposition of bare and PEO-coated latex particles onto glass interfaces was also investigated. From the data it was found that bare and smooth latex particles adsorb much more strongly onto collector surfaces than "hairy" latex particles which have long copolymer chains, such as itachonic acid, grafted onto their surfaces. The results indicated that the thicker the adsorbed polymer layer, the stronger the steric force preventing deposition of the polymer coated colloidal particles onto the collector surface. When the combined ellipsometric layer thickness of the particles and the collector surface exceeded a critical value, found to be about 15 nm, no particle deposition onto the collector surface was possible.
35
Wu, Qinghua 1977. "Self-assembly of poly(ethylene oxide)-b-polystyrene-b-poly(acrylic acid) triblock copolymers in solution". Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=98522.
Pełny tekst źródłaStreszczenie:
The self-assembly behavior of poly(ethylene oxide)-b-polystyrene- b-poly(acrylic acid) (PEO-b-PS-b-PAA) triblock copolymers in solution is the focus of this thesis. The triblock copolymers were synthesized by atom transfer radical polymerization (ATRP). The compositions of the block copolymers were determined by 1H NMR. The synthesized block copolymers have relatively low polydispersity indexes (PDI < 1.3) as proved by GPC. The influence of several factors on the ATRP of styrene or t-BA, such as temperature, catalyst and polymerization time, was also explored. The effects of several parameters on the self-assembly behavior of this triblock copolymer were investigated, including the nature and composition of the common solvent, PAA block length, pH, water content, and initial copolymer concentration. Multiple morphologies, such as spheres, vesicles, lamellae and rods have been prepared by varying the above parameters. In particular, vesicles with either PEO or PAA outside have been successfully prepared in dioxane/water. These vesicles may serve as carriers for potential encapsulation applications. The average size and corona chain composition of the triblock copolymer vesicles can be controlled by varying factors such as the PAA block length and pH. The polymer chains may have different arrangements in the vesicle wall, resulting in different corona chain compositions. The vesicles with PAA outside are stable in water, while the vesicles with PEO outside tend to flocculate. Nevertheless, the sediment can be redispersed under vigorous stirring.
36
Vu, Quoc Trung. "Electrophoretic deposition of semiconducting polymer metal oxide nanocomposites and characterization of the resulting films". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1137420064480-98497.
Pełny tekst źródłaStreszczenie:
Conducting polymer nanocomposites composed of metal oxides and polythiophene was synthesized by chemical polymerization in colloidal suspensions. The electrochemical and photoelectrochemical properties of such nanocomposites have been studied. For these investigations films of nanocomposites were prepared by an electrophoretic deposition process. The deposition process was studied in greater detail and kinetic details were determined. The high voltage electrophoretic deposition process was combined with a quartz crystal microbalance (QCM). Then the films were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and photocurrent spectroscopy.
37
Anderson, Virginia Rose. "Atomic Layer Deposition of Platinum Particles, Titanium Oxide Films, and Alkoxysilane Surface Layers". Thesis, University of Colorado at Boulder, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3621292.
Pełny tekst źródłaStreszczenie:
Atomic Layer Deposition (ALD) is a an excellent technique for depositing conformal thin films on complex geometries in layer by layer fashion. The mechanisms of depositing TiO2, platinum, and ethoxysilane molecules were probed with in situ Fourier transform infrared (FTIR) in order to better understand and improve the process. Each of these studies involves TiO2.
There are many uses for thin films of titanium dioxide, a semiconductor and high dielectric material. Current Atomic Layer Deposition (ALD) of TiO 2 generally involves water or ozone, which can oxidize and corrode some substrates of interest. Ritala et al. successfully deposited an assortment of metal oxides using no water, but instead, metal alkoxides and metal halides as precursors. Presented is a study of ALD of titanium dioxide using titanium tetrachloride (TiCl4) and titanium tetraisopropoxide (TTIP). In situ Fourier transform infrared (FTIR) studies revealed that the mechanism for TiO2 ALD using titanium tetrachloride and titanium tetraisopropoxide changed with temperature. At temperatures between 250 and 300°, the isopropoxide species after TTIP exposures quickly underwent β-hydride elimination to produce TiOH species on the surface. The observation of propene by quadrupole mass spectrometry supported the β-hydride elimination reaction pathway. Deposition was investigated between 150 and 300° on substrates including zirconia, alumina, and silica. Quartz crystal microbalance results and X-ray reflectivity showed that the system grew 0.5–0.6 Å/cycle at 250° X-Ray photoelectron studies also confirmed TiO2 film growth.
In another aspect of ALD use, self-limiting chemistry assisted with terminating a surface with alkoxysilanes. Tire rubber contains additives such as carbon black or silica particles to provide strength. Although in theory Kevlar fibers would provide strength while lowering the density and increasing car fuel efficiency, in practice Kevlar fibers disperse only very poorly in the rubber, leading to inhomogeneity. In order the increase the mixing likelihood between rubber and Kevlar, the reactions of some sulfurous siloxanes were examined on both aluminum oxide and titanium oxide. The titanium oxide adhesion layer allowed the deposition of molecules on the surface that looked promising for improving mixing with rubber and decreasing the weight of tires.
Atomic layer deposition offers the possibility of more precision in platinum deposition. In a platinum deposition study, the nucleation and growth of non-conformal platinum on TiO2 and WOx powder using Pt(hfac) 2 and formalin was examined with in-situ FTIR and transmission electron microscopy (TEM). Interest in substitution of Pt/C as the oxidation reduction reaction catalyst in polymer electrolyte membrane fuel cells (PEMFCs) led to the ALD synthesis of Pt/WOx and Pt/TiO2. A nucleation period on the order of 100 cycles was observed, after which, platinum loading and particle size measurably increased with increasing cycle number. The adsorption of the hfac ligand on the metal oxide substrate effectively inhibits nanoparticle coalescence during the growth phase, which led to further investigation of its use as a site-blocking agent. The results showed that Pt particle distance could be increased with the use of hfacH.
38
Hamza, Ali Abdalla. "Preparation and performance testing of sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) - polyethersulfone thin film composite membranes". Thesis, University of Ottawa (Canada), 1995. http://hdl.handle.net/10393/9576.
Pełny tekst źródłaStreszczenie:
Thin film composite membranes were prepared by coating the surface of polyethersulfone ultrafilnation membranes with dilute solutions of sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) polymer. Poly(2,6-dimethyl-1,4-phenylene oxide) was first sulfonated to different degrees, thus obtaining polymers of different ion exchange capacities, from which the coating solutions in methanol or methanol/chloroform mixtures were prepared. The reverse osmosis performance of the thin film composite membranes was studied using electrolyte solutes of different valences and ionic radii. The effect of the solvent used for the preparation of the polymer solution for surface coating was also investigated through testing the performance of the composite membranes in separating different electrolyte solutions as well as by micrographic techniques using a Scanning Electron Microscope and an Atomic Force Microscope. It was found that the preparation of thin film composite membranes with high selectivity and high flux was possible by adjusting properly the ion exchange capacity and the solvent used in making the coating solution. It was also found that the membrane performance was governed primarily by the ion exchange reaction between the solute cation and the proton in-SO$\sb3\sp{-}$H$\sp{+},$ as well as by the Donnan equilibrium. An attempt was also made to investigate the effect of changing the microporous substrate of the thin film composite membrane on the membrane permeation rate and selectivity. The porosity and the structure of the substrate play a significant role in determining the performance of the composit membrane.
39
Li, Bohao. "Room Temperature Processed Molybdenum Oxide Thin Film as a Hole Extraction Layer for Polymer Photovoltaic Cells". University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1368015443.
Pełny tekst źródła
40
Miles, William Clayton. "The Design of Stable, Well-Defined Polymer-Magnetite Nanoparticle Systems for Biomedical Applications". Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/28725.
Pełny tekst źródłaStreszczenie:
The composition and stability of polymer-magnetite complexes is essential for their use as a treatment for retinal detachment, for drug targeting and delivery, and for use as a MRI contrast agent. This work outlines a general methodology to design well-defined, stable polymer-magnetite complexes. Colloidal modeling was developed and validated to describe polymer brush extension from the magnetite core. This allowed for the observation of deviations from expected behavior as well as the precise control of polymer-particle complex size. Application of the modified Derjaguin-Verwey-Landau-Overbeek (DLVO) theory allowed the determination of the polymer loading and molecular weight necessary to sterically stabilize primary magnetite particles.
Anchoring of polyethers to the magnetite nanoparticle surface was examined using three different types of anchor groups: carboxylic acid, ammonium, and zwitterionic phosphonate. As assessed by dynamic light scattering (DLS), the zwitterionic phosphonate group provided far more robust anchoring than either the carboxylic acid or ammonium anchor groups, which was attributed to an extremely strong interaction between the phosphonate anchor and the magnetite surface. Coverage of the magnetite surface by the anchor group was found to be a critical design variable for the stability of the zwitterionic phosphonate groups, and the use of a tri-zwitterionic phosphonate anchor provided stability in phosphate buffered saline (PBS) for a large range of polymer loadings.
Incorporation of an amphiphlic poly(propylene oxide)-b-poly(ethyelene oxide) (PPO-b-PEO) diblock copolymer attached to the magnetite surface was examined through colloidal modeling and DLS. The relaxivity of the complexes was related to aggregation behavior observed through DLS. This indicated the presence of a hydrophobic interaction between the PPO layers of neighboring complexes. When this interaction was large enough, the complexes exhibited an increased relaxivity and cellular uptake.
Thus, we have developed a methodology that allows for design of polymer-magnetite complexes with controlled sizes (within 8% of predicted values). Application of this methodology incorporated with modified DLVO theory aids in the design of colloidally stable complexes with minimum polymer loading. Finally, determination of an anchor group stable in the presence of phosphate salts at all magnetite loadings allows for the design of materials with minimum polymer loadings in biological systems.Ph. D.
41
Signorini, Virginia. "Hybrid polymer-based membranes with graphene oxide nanoparticles for carbon dioxide capture". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Znajdź pełny tekst źródłaStreszczenie:
The project focuses on the development of hybrid polymer/inorganic membranes with aligned nanoparticles within the polymeric matrix for CO2 separation membrane fabrication. The investigated polymer is the PEG3A, while the inorganic particles are the Graphene Oxide (GO).
The addition of the GO nanoparticles is done due to a UV-light cross-linking reaction between the polymer, the polymer solvent and the solvent in which nanoparticles are dispersed in different concentration. The solvents used for the incorporation of GO into the membrane matrix are Water, Ethanol and Acetone since these fillers are considered non-toxic for human being.
The membrane alignment is expected to improve the performance for CO2/N2 and CO2/He separation application which had been calculated by testing each membrane with the Single Gas Apparatus with the same operative condition.
The compatibility of the polymers and nanoparticles will be characterized by using different techniques such as SEM, TGA and DSC, in order to develop the optimal hybrids for the carbon capture.
42
Downing, Jonathan Mark. "Control and characterisation of metal oxide/polymer morphologies for hybrid photovoltaic devices". Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/39349.
Pełny tekst źródłaStreszczenie:
The ready formation of nanostructures, combined with excellent optoelectronic properties has shown zinc oxide (ZnO) to be a promising material for use in photovoltaic devices. Hybrid photovoltaic (h-PV) devices composed of metal oxide-organic pairings are currently limited by ineffective charge transfer between the materials and by poor transport of free charge out of the active layer. Control of interfacial properties, and the structure and morphology of each component is key to device optimisation. In this thesis, ZnO nanorods are paired with the photoactive polymer, poly 3-hexlythiophene (P3HT) with two areas studied: i) nanorod alignment to aid polymer infiltration, and ii) elucidating optimum polymer processing conditions to prepare efficient devices. Aligned nanorods are synthesised from ZnO coated substrates by a hydrothermal method. To understand the influence of ionic additives on morphological control, the addition of potassium chloride (KCl) to growth solutions is investigated. Films have been studied by SEM and XRD, with the correlation of these results (nanorod length, width, density vs (002) diffraction peak area) used to examine alignment, which increases at higher concentrations. This ordering is explained via a geometrical selection argument. Effective polymer infiltration into nanorod arrays is found to be possible by spin coating and annealing above the polymer melting point. Extended annealing (> 60 seconds) is seen to reduce device performance. Small angle X-ray scattering and X-ray diffraction as a function of temperature was conducted to investigate polymer orientation and the kinetics of crystallisation within nanostructured films. These results are combined with device measurements to aid in understanding the relationship between morphological characteristics of the constituent materials and h-PV performance.
43
Wilke, Philipp Verfasser], Andrij Z. [Akademischer Betreuer] [Pich i Doris [Akademischer Betreuer] Klee. "Zinc oxide based polymer hybrid materials / Philipp Wilke ; Andrij Pich, Doris Klee". Aachen : Universitätsbibliothek der RWTH Aachen, 2015. http://d-nb.info/1126646393/34.
Pełny tekst źródła
44
Costa, Dantas Faria Jorge. "Effect of polymer and metal oxide properties on hybrid light emitting diodes". Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/43381.
Pełny tekst źródłaStreszczenie:
Hybrid organic/inorganic light-emitting diodes (HyLEDs) combine thin, metal oxide layers together with light-emitting organic semiconductors to create devices that are more resilient to ambient conditions than standard devices. In this thesis, HyLED performance is measured as a function of the individual organic and oxide layer properties with the aims of addressing several perceived gaps within reported literature and to consequently optimise future device design. Reported herein are the results of the insertion of a vertical zinc oxide nanorod array as a non-planar, bottom-cathode electron injection layer. Using facile solution-processing methods, a well-aligned and uniform array was deposited into which the light emitting polymer poly(9,9'-dioctylfluorene-co-benzothiadiazole) (F8BT) was then melt-processed to create a massive, 3D interfacial contact area for electron injection. This study recorded, for the first time, efficiency and luminance values for a vertical nanorod-based LED with maximum figures of 1.66 cd/A and 8602 cd/m2 showing their potential for display and lighting applications. The successful demonstration of these nanorod HyLEDs was due to the insertion of a poly[(9,9-dioctylfluore-nyl-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine)] (TFB) at the F8BT/anode interface to block electrons and reduce the probability of interfacial exciton dissociation. Using post-deposition annealing and solution processing, a robust method of casting TFB onto F8BT without the need for lift-off steps is presented. In planar devices, the insertion of TFB increases the maximum recorded efficiencies from 0.024 to 1.0 cd/A and its role as an optical emission tuning layer was also demonstrated; by simply varying the layer thickness the F8BT electro-luminescence was tuned from green emission to orange. Finally, the molecular weight of F8BT was seen to significantly influence the performance of HyLEDs, with six separate batches ranging from 36 to 300 kg/mol providing a systematic device study. Importantly, these batches were extracted from a single commercial source using gel permeation chromatography to negate the possible influence of different synthesis routes and chain ends. The thesis is organised into six chapters. Chapter 1 focuses on the principles behind device design and operation with an overview of the current state of HyLED literature and a discussion of the principle materials studied. Chapter 2 provides a general description of the experimental procedures and techniques used throughout. Chapters 3 to 5 each focus on a specific experimental investigation and are largely self-contained with each presenting - along with a discussion of the results - a literature review, a list of aims and an experimental section particular to the study conducted. Finally, Chapter 6 provides general concluding remarks, expanding on the ideas of further work discussed within Chapters 3-5.
45
Harris, Linda Ann. "Polymer Stabilized Magnetite Nanoparticles and Poly(propylene oxide) Modified Styrene-Dimethacrylate Networks". Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/27547.
Pełny tekst źródłaStreszczenie:
Magnetic nanoparticles that display high saturation magnetization and high magnetic susceptibility are of great interest for medical applications. Nanomagnetite is particularly desirable because it displays strong ferrimagnetic behavior, and is less sensitive to oxidation than magnetic transition metals such as cobalt, iron, and nickel. Magnetite nanoparticles can be prepared by co-precipitating iron (II) and iron (III) chloride salts in the presence of ammonium hydroxide at pH 9-10. One goal of this work has been to develop a generalized methodology for stabilizing nanomagnetite dispersions using well-defined, non-toxic, block copolymers, so that the resultant magnetite-polymer complexes can be used in a range of biomedical materials.
Hydrophilic triblock copolymers with controlled concentrations of pendent carboxylic acids were prepared. The triblock copolymers contain carboxylic acids in the central urethane segments and controlled molecular weight poly(ethylene oxide) tail blocks. They were utilized to prepare hydrophilic-coated iron oxide nanoparticles with biocompatible materials for utility in magnetic field guidable drug delivery vehicles. The triblock copolymers synthesized contain 3, 5, or 10 carboxylic acids in the central segments with Mn values of 2000, 5000 or 15000 g/mol poly(ethylene oxide) tail blocks. A method was developed for preparing ~10 nm diameter magnetite surfaces stabilized with the triblock polymers. The carboxylic acid is proposed to covalently bind to the surface of the magnetite and form stable dispersions at neutral pH. The polymer-nanomagnetite conjugates described in this thesis have a maximum of 35 wt. % magnetite and the nano-magnetite particles have an excellent saturation magnetization of ~66 - 78 emu/g Fe3O4. Powder X-ray diffraction (XRD) confirms the magnetite crystal structure, which appears to be approximately single crystalline structures via electron diffraction spectroscopy analysis (EDS). These materials form stable magnetic dispersions in both water and organic solvents.Ph. D.
46
Wilke, Philipp [Verfasser], Andrij Z. [Akademischer Betreuer] Pich i Doris [Akademischer Betreuer] Klee. "Zinc oxide based polymer hybrid materials / Philipp Wilke ; Andrij Pich, Doris Klee". Aachen : Universitätsbibliothek der RWTH Aachen, 2015. http://d-nb.info/1126646393/34.
Pełny tekst źródła
47
Zhang, Ming. "Nonaqueous Synthesis of Metal Oxide Nanoparticles and Their Surface Coating". ScholarWorks@UNO, 2008. http://scholarworks.uno.edu/td/861.
Pełny tekst źródłaStreszczenie:
This thesis mainly consists of two parts, the synthesis of several kinds of technologically interesting crystalline metal oxide nanoparticles via high temperature nonaqueous solution processes and the formation of core-shell structure metal oxide composites using some of these nanoparticles as the core with silica, titania or polymer as shell via a modified microemulsion approach. In the first part, the experimental procedures and characterization results of successful synthesis of crystalline iron oxide (Fe3O4) and indium oxide (In2O3) nanoparticles are reported. Those nanoparticles exhibit monodispersed particle size, high crystallinity and high dispersibility in non-polar solvents. The particle size can be tuned by the seed mediated growth and the particle shape can also be controlled by altering the capping ligand type and amount. The mixed bi-metal oxides such as cobalt iron oxide and lithium cobalt oxide will be discussed as well. In the second part, the synthesis and characterization of various surface coated metal oxides, including silica, titania and polymer coated nanocomposites are reported. The silica coating process is presented as a highlight of this part. By using a microemulsion system, core-shell structure silica coated iron oxide and indium oxide nanocomposites are successfully prepared. Furthermore, the thickness of the silica coating can be controlled from 2 nm to about 100 nm by adjusting the reaction agents of the micelle system. By extending the procedure, we will also discuss the titania and polymer coating preparation and characterization.
48
Akbarian-Tefaghi, Sara. "Microwave-Assisted Topochemical Manipulation of Layered Oxide Perovskites: From Inorganic Layered Oxides to Inorganic-Organic Hybrid Perovskites and Functionalized Metal-Oxide Nanosheets". ScholarWorks@UNO, 2017. http://scholarworks.uno.edu/td/2287.
Pełny tekst źródłaStreszczenie:
Developing new materials with desired properties is a vital component of emerging technologies. Functional hybrid compounds make an important class of advanced materials that let us synergistically utilize the key features of the organic and inorganic counterparts in a single composite, providing a very strong tool to develop new materials with ”engineered” properties. The research presented here, summarizes efforts in the development of facile and efficient methods for the fabrication of three- and two-dimensional inorganic-organic hybrids based on layered oxide perovskites. Microwave radiation was exploited to rapidly fabricate and modify new and known materials. Despite the extensive utilization of microwaves in organic syntheses as well as the fabrication of the inorganic solids, the work herein was among the first reported that used microwaves in topochemical modification of the layered oxide perovskites. Our group specifically was the first to perform rapid microwave-assisted reactions in all of the modification steps including proton exchange, grafting, intercalation, and exfoliation, which decreased the duration of multi-step modification procedures from weeks to only a few hours. Microwave-assisted grafting and intercalation reactions with n-alkyl alcohols and n-alkylamines, respectively, were successfully applied on double-layered Dion-Jacobson and Ruddlesden-Popper phases (HLaNb2O7, HPrNb2O7, and H2CaTa2O7), and with somewhat more limited reactivity, applied to triple-layered perovskites (HCa2Nb3O10 and H2La2Ti3O10). Performing neutron diffraction on n-propoxy-LaNb2O7, structure refinement of a layered hybrid oxide perovskite was then tried for the first time. Furthermore, two-dimensional hybrid oxides were efficiently prepared from HLnNb2O7 (Ln = La, Pr), HCa2Nb3O10, HCa2Nb2FeO9, and HLaCaNb2MnO10, employing facile microwave-assisted exfoliation and post-exfoliation surface-modification reactions for the first time. A variety of surface groups, saturated or unsaturated linear and cyclic organics, were successfully anchored onto these oxide nanosheets. Properties of various functionalized metal-oxide nanosheets, as well as the polymerization of some monomer-grafted nanosheets, were then investigated for the two-dimensional hybrid systems.
49
Marentette, Joanne M. (Joanne Marie). "The crystallization of poly(ethylene oxide) in blends with neat and plasticized poly(vinyl chloride)". Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29082.
Pełny tekst źródłaStreszczenie:
The crystallization of poly(ethylene oxide) (PEO) in blends with amorphous poly(vinyl chloride) (PVC), in a mixture with the PVC-selective plasticizer tricresyl phosphate (TCP), and in ternary mixtures with both PVC and TCP has been investigated at several structural levels using the techniques of: (i) theoretical surface interfacial tension calculations, (ii) thermal analysis, (iii) polarized light microscopy, and (iv) polarized infrared microspectroscopy.The invariance of the glass transition temperature of the interlamellar, amorphous PEO suggests a relatively low degree of dispersion in PEO/PVC blends. A slight depression in the equilibrium melting temperature of PEO in blends of high PVC content was observed, and subsequent analysis of the data using the Flory-Huggins equation reveals that, at best, PEO and PVC exhibit limited miscibility in the melt. The melting temperature depression may be accentuated by the addition of TCP, but the depression observed in the ternary mixtures lies within the experimental uncertainty.
In general, the spherulites grown in the presence of additives are coarser and less birefringent than those grown in the pure melt, with the degree of coarseness increasing with increasing additive concentration. The interpretation of the crystallization kinetics of PEO using current nucleation theory clearly demonstrates that the crystallization of PEO in the temperature range of interest occurs within regime III. The slight kinetic discontinuity at $ sim$51$ sp circ$C that has been thought to arise from a regime II/III transition can be attributed to a transformation of the dominant crystal growth face from the (010) crystallographic face at lower temperatures to the (120) face at higher temperatures. The growth rates of PEO spherulites in PEO/PVC blends are not affected by the presence of PVC in the temperature range 49-55$ sp circ$C, even at concentrations as high as 50% PVC. However, the growth rates of spherulites in mixtures containing TCP are significantly depressed.
Dichroic infrared microspectroscopy was employed to investigate the variations in the crystalline structure at the sub-spherulitic level. The determination of the dichroic ratios and the selected peak ratios from the spectra of purely crystalline PEO (obtained by difference spectroscopy) reveals that PVC disturbs the orientation of the crystalline stems of PEO within the spherulites and causes an increase in the crystallization of PEO in the strained, planar zig-zag conformation. PEO, in turn, appears to induce a higher incidence of the planar zig-zag conformation in the PVC molecules. In the ternary mixtures, the plasticizing effect of TCP on PVC renders the PVC molecules more flexible and more mobile, thereby drastically reducing the shearing of the PEO and the resultant formation of the planar zig-zag conformation during crystallization. In effect, the crystallization kinetics and the basic crystalline structure of PEO can be controlled by selection of appropriate proportions of PVC and TCP, a result of major significance and practical importance to the field of polymer blends.
50
ALRASHED, MAHER M. "ORGANIC/INORGANIC HYBRID COATINGS FOR ANTICORROSION APPLICATIONS". University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1491226580793534.
Pełny tekst źródła