To see the other types of publications on this topic, follow the link: Novel Nanoporous Organic Materials.
Dissertations / Theses on the topic 'Novel Nanoporous Organic Materials'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Novel Nanoporous Organic Materials.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Mangano, Enzo. "Rapid screening of novel nanoporous materials for carbon capture separations." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/9497.
Full textAbstract:
In this work the experimental results from the rapid screening and ranking of a wide range of novel adsorbents for carbon capture are presented. The samples were tested using the Zero Length Column (ZLC) method which has proved to be an essential tool for the rapid investigation of the equilibrium and kinetic properties of prototype adsorbents. The study was performed on different classes of nanoporous materials developed as part of the EPSRC-funded “Innovative Gas Separations for Carbon Capture” (IGSCC) project. More than 120 novel adsorbents with different key features for post-combustion carbon capture were tested. The classes of materials investigated were: • PIMs (Polymers of Intrinsic Microporosity) • MOFs (Metal - Organic Frameworks) • Mesoporous Silica • Zeolites • Carbons All the samples were tested at experimental conditions close to the ones of a typical flue gas of a fossil fuel power plant: 35 ºC and 0.1 bar of partial pressure of CO2. The results from the ranking of the CO2 capacity of the materials, at the conditions of interest, indicate the Mg and Ni-based MOF samples as the adsorbents with the highest uptake among all the candidates. The best sample shows a CO2 capacity almost double than the benchmark adsorbent, zeolite 13X (provided by UOP). The ranking also shows some of the zeolite adsorbents synthesised as promising materials for carbon capture: uptakes comparable or slightly higher than 13X were obtained for several samples of Rho and Chabazite zeolite. Water stability tests were also performed on the best MOFs and showed a deactivation rate considerably faster for the Mg-based MOFs, proving an expected higher resistance to degradation for the Ni based materials. A focused investigation was also carried out on the diffusion of CO2 in different ionexchanged zeolites Rho samples. The study of these samples, characterised by extremely slow kinetics, extended the use of the ZLC method to very slow diffusional time constants which are very difficult to extract from the traditional long time asymptotic analysis. The results show how the combination of the full saturation and partial loading experiment can provide un-ambiguous diffusional time constants. The diffusivity of CO2 in zeolite Rho samples shows to be strongly influenced by the framework structure as well as the nature and the position of the different cations in the framework. The kinetics of the Na-Cs Rho sample was also measured by the use of the Quantachrome Autosorb-iQ™ volumetric system. To correctly interpret the dynamic response of the instrument modifications were applied to the theoretical model developed by Brandani in 1998 for the analysis of the piezometric method. The analytical solution of the model introduces parameters which allow to account for the real experimental conditions. The results confirm the validity of the methodology in the analysis of slow diffusion processes. In conclusion the advantages offered by the small size of the column and the small amount of sample required proved the ZLC method to be a very useful tool for the rapid ranking of the CO2 capacity of prototype adsorbents. Equilibrium and kinetic measurements were performed on a very wide range of novel nanoporous materials. The most promising and interesting samples were further investigated through the use of the water stability test, the partial loading experiment and the volumetric system. The ZLC technique was also extended to the measurements of systems with very slow kinetics, for which is very difficult to extract reliable diffusional time constants. An improved model for the interpretation of dynamic response curves from a non-ideal piezometric system was developed.
2
Liu, Yuanyuan. "DEVELOPMENT OF METAL-ORGANIC FRAMEWORK-BASED NANOPOROUS MATERIALS FOR ADSORPTION APPLICATIONS." Kent State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=kent1542906215640054.
Full text
3
Vuong, Gia Thanh. "Synthesis and characterization of nanoporous materials: nanozeolites and metal-organic frameworks." Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/29925/29925.pdf.
Full textAbstract:
Dans ce travail, deux types de nanomatériaux poreux ont été obtenues: des nanozéolithes et des matériaux à réseau organométallique (MOF). Pour les nanozéolithes, deux nouvelles méthodes de synthèses ont été développé: une méthode à phase unique et une méthode biphasique. Dans la méthode à phase unique, une quantité du gel-zéolithique est ajoutée à une solution de toluène/n-butanol contenant l’agent silylant organosilane. Après 12 heures à 60oC, une phase homogène est obtenue. Ce mélange est traité hydrothermalement pour produire une nanozéolithe fonctionalisée. En revanche, la méthode de synthèse à deux phases, implique l’introduction de l’organosilane mélangé à un solvant organique dans le gel de zéolithe aqueux conduisant ainsi à un mélange biphasique. Après mélange et traitement hydrothermal, des nanozéolithes fonctionalisées par silylation sont obtenu dans la phase organique et de larges cristaux de zéolithes sont obtenus dans la phase aqueuse. En principe, les deux méthodes utilisent l’organosilane pour empêcher la croissance des cristaux. Le solvant organique joue le rôle de dispersant des nanozéolithes fonctionalisées avec l’organosilane à partir de la phase aqueuse, et contrôle le processus de croissance des nanozéolithes. Ces deux méthodes de synthèse sont applicables autant aux zéolithes MFI que FAU, telles que silicatite-1, ZSM-5 et NaY. Elles peuvent être étendues à la synthèse d’autres types de zéolithes. L’activité catalytique de ces nanozéolithes a été évaluée pour le craquage de FCC. Les résultats indiquent que la nanozéolithe de type FAU montre une bonne activité dans cette réaction. Pour l’étude des matériaux à réseau organométallique (MOF), une nouvelle approche a été développé pour la synthèse de MIL-88B en utilisant un cluster neutre de métaux mixtes bimétalliques Fe2Ni(µ3-O). Les clusters occupent les nœuds du réseau MIL-88B à la place du mono-métal Fe3 (µ3-O) avec un anion compensateur. Ce dernier est le cluster formant le réseau du Fe3MIL-88B non-poreux qui est obtenu par la méthode conventionnelle. De ce fait, en absence des anions compensateurs dans la structure, Fe2Ni MIL-88B devient un matériau poreux. De plus, avec la combinaison de la flexibilité de MIL-88B et des métaux mixtes comme nœuds dans le réseau, la porosité peut être contrôlée par échange avec des ligands terminaux du réseau. Ceci nous a permis de moduler d’une manière réversible la porosité de MIL-88B à différents niveaux, ainsi que la surface spécifique et le volume de pores dépendant de taille de ligands échangés. Le mécanisme de synthèse a été aussi étudié pour les matétiaux Fe3-MIL88B et Fe2Ni-MIL88B. Les résultats montrent que pour la synthèse de Fe3-MIL88B, le mono-métal Fe3-MOF-235 est comme le précurseur pour la formation de MIL-88B. Dans le cas d’utilisation de métaux mixtes Fe2Ni(µ3-O), les mono-métal Fe3-MOF-235 est formés en premier lors de la synthèse du métal mixte Fe2Ni-MIL88B. Il est montré que la présence de l’anion FeCl4- est déteminante dans la formation de la phase initiale MOF-235 et dans le succès de la synthèse du MIL-88B mono- ou bimétallique. L’anion FeCl4- est très important pour le succès de la formation de MOF-235. Un mécanisme d’anion médiateur dans la formation de MOF-235 a été suggéré.In this thesis, two types of nanoporous materials: nanozeolites and metal-organic frameworks were studies. For nanozeolites, two novel methods e.g. single-phase and two-phases were reported for the synthesis of nanozeolites. In the single-phase synthesis method, a proper amount of zeolite gel solution was added to a toluene/n-butanol solution containing an organosilane. After 12 hours at 60oC, a single phase mixture was obtained. This mixture was then subjected to hydrothermal crystallization to produce uniform functionalized nanozeolites. In contrast, the two-phase synthesis method involved the introduction of an organic solvent containing organosilane to the aqueous zeolite gel solution, resulting in a two-phase mixture. Upon mixing and hydrothermal treatment of this mixture, organosilane-functionalized nanozeolites were obtained in the organic phase whereas, large zeolite crystals were found in the aqueous phase. In principle, both methods employed the use of organosilane to inhibit the crystal growth. The organic solvent acted as the medium for the dispersion of nanozeolites functionalized with organosilane from the aqueous phase, which led to the complete halt of the growth process. These two methods were demonstrated to be applicable to the synthesis of MFI and FAU nanozeolites such as silicalite-1 and NaY, and could be applied to the synthesis of other types of zeolites. Catalytic activity of the synthesized nanozeolites was evaluated by the cracking reaction of FCC feed. The result showed that FAU nanozeolites can be good catalysts for the cracking reaction. For the study of the metal-organic frameworks (MOF), a new rational approach was developed for the synthesis of mixed metal MIL-88B metal organic framework based on the use of neutral bimetallic cluster, such as Fe2Ni(µ3-O) cluster. Unlike the conventional negative charged single metal cluster, the use of neutral bimetallic cluster as a framework node avoids the need of compensating anion inside porous MIL-88B system; thus such a bimetallic MIL-88B becomes porous. The flexibility of the mixed metal MIL-88B can be controlled by terminal ligands with different steric hindrance. This allows us to reversibly customize the porosity of MIL-88B structure at three levels of specific surface area as well as the pore volume. Synthesis mechanism was also studied. It was found that the monometallic Fe3-MOF-235 is the precursors to the formation of MIL-88B. MOF-235 comes first then later transforms to Fe3-MIL-88B or acts as seeds for the formation of mixed Fe2Ni-MIL88B. FeCl4- anion is very important to the successful formation of MOF-235. An anion mediated mechanism of the formation of MOF-235 is suggested.
4
Sun, Zhengfei Wei Yen. "Novel sol-gel nanoporous materials, nanocomposites and their applications in bioscience /." Philadelphia, Pa. : Drexel University, 2005. http://dspace.library.drexel.edu/handle/1860/556.
Full text
5
Smith, Helen. "Novel organic materials for photovoltaic devices." Thesis, University of Glasgow, 2014. http://theses.gla.ac.uk/5859/.
Full textAbstract:
Organic materials offer key advantages over their inorganic counterparts for photovoltaics due to the ability to easily tune the physical properties and develop cheaper, more flexible, photovoltaic devices. This thesis describes the synthesis and characterisation of a variety of compounds from small-molecule to supramolecular and polymeric systems with the potential to be used in organic electronics. Herein is described an optimised synthetic route for the synthesis of two flavins and the synthesis and characterisation of a novel flavin and fluorene polymer. Also described is the synthesis of two novel rotaxane structures with the potential for use in organic field effect transistors. The synthesis of a novel polymer incorporating the naphthalene diimide moiety and a P3HT functionality utilising click methodology is also described. Finally the synthesis of a thiophene based star shaped molecule as electron transporting material is also described along with a flavin based organic dye for use in dye-sensitised solar cells.
6
Paxton, G. A. N. "Novel organic materials for gas sensing." Thesis, Cranfield University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273584.
Full text
7
Jones, Christopher Lloyd. "Some novel oligothiophene-based materials." Thesis, University of Liverpool, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343689.
Full text
8
Bae, Tae-Hyun. "Engineering nanoporous materials for application in gas separation membranes." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/42712.
Full textAbstract:
The main theme of this dissertation is to engineer nanoporous materials and nanostructured surfaces for applications in gas separation membranes. Tunable methods have been developed to create inorganic hydroxide nanostructures on zeolite surfaces, and used to control the inorganic/polymer interfacial morphology in zeolite/polymer composite membranes. The study of the structure-property relationships in this material system showed that appropriate tuning of the surface modification methods leads to quite promising structural and permeation properties of the membranes made with the modified zeolites. First, a facile solvothermal deposition process was developed to prepare roughened inorganic nanostructures on zeolite pure silica MFI crystal surfaces. The functionalized zeolite crystals resulted in high-quality ̒mixed matrix̕ membranes, wherein the zeolite crystals were well-adhered to the polymeric matrix. Substantially enhanced gas separation characteristics were observed in mixed matrix membranes containing solvothermally modified MFI crystals. Gas permeation measurements on membranes containing nonporous uncalcined MFI revealed that the performance enhancements were due to significantly enhanced MFI-polymer adhesion and distribution of the MFI crystals. Solvothermal deposition of inorganic nanostructures was successfully applied to aluminosilicate LTA surfaces. Solvothermal treatment of LTA was tuned to deposit smaller/finer Mg(OH)₂ nanostructures, resulting in a more highly roughened zeolite surface. Characterization of particles and mixed matrix membranes revealed that the solvothermally surface-treated LTA particles were promising for application in mixed matrix membranes. Zeolite LTA materials with highly roughened surfaces were also successfully prepared by a new method: the ion-exchange-induced growth of Mg(OH)₂ nanostructures using the zeolite as the source of the Mg²⁺ ions. The size/shape of the inorganic nanostructures was tuned by adjusting several parameters such as the pH of the reagent solution and the amount of magnesium in the substrates and systematic modification of reaction conditions allowed generation of a good candidate for application in mixed matrix membranes. Zeolite/polymer adhesion properties in mixed matrix membranes were improved after the surface treatment compared to the untreated bare LTA. Surface modified zeolite 5A/6FDA-DAM mixed matrix membranes showed significant enhancement in CO₂ permeability with slight increases in CO₂/CH₄ selectivity as compared to the pure polymer membrane. The CO₂/CH₄ selectivity of the membrane containing surface treated zeolite 5A was much higher than that of membrane with untreated zeolite 5A. In addition, the use of metal organic framework (MOF) materials has been explored in mixed matrix membrane applications. ZIF-90 crystals with submicron and 2-μm sizes were successfully synthesized by a nonsolvent induced crystallization technique. Structural investigation revealed that the ZIF-90 particles synthesized by this method had high crystallinity, microporosity and thermal stability. The ZIF-90 particles showed good adhesion with polymers in mixed matrix membranes without any compatibilization. A significant increase in CO₂ permeability was observed without sacrificing CO₂/CH₄ selectivity when Ultem® and Matrimd® were used as the polymer matrix. In contrast, mixed matrix membranes with the highly permeable polymer 6FDA-DAM showed substantial enhancement in both permeability and selectivity, as the transport properties of the two phases were more closely matched.
9
Richards, Gary J. "Novel organic materials for electroluminescent display devices." Thesis, University of Hull, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342862.
Full text
10
Haldoupis, Emmanuel. "Mulitscale modeling and screening of nanoporous materials and membranes for separations." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47669.
Full textAbstract:
The very large number of distinct structures that are known for metal-organic frameworks (MOFs) and zeolites presents both an opportunity and a challenge for identifying materials with useful properties for targeted separations. In this thesis we propose a three-stage computational methodology for addressing this issue and comprehensively screening all available nanoporous materials. We introduce efficient pore size calculations as a way of discarding large number of materials, which are unsuitable for a specific separation. Materials identified as having desired geometric characteristics can be further analyzed for their infinite dilution adsorption and diffusion properties by calculating the Henry's constants and activation energy barriers for diffusion. This enables us to calculate membrane selectivity in an unprecedented scale and use these values to generate a small set of materials for which the membrane selectivity can be calculated in detail and at finite loading using well-established computational tools. We display the results of using these methods for >500 MOFs and >160 silica zeolites for spherical adsorbates at first and for small linear molecules such as CO₂ later on. In addition we also demonstrate the size of the group of materials this procedure can be applied to, by performing these calculations, for simple adsorbate molecules, for an existing library of >250,000 hypothetical silica zeolites. Finally, efficient methods are introduced for assessing the role of framework flexibility on molecular diffusion in MOFs that do not require defining a classical forcefield for the MOF. These methods combine ab initio MD of the MOF with classical transition state theory and molecular dynamics simulations of the diffusing molecules. The effects of flexibility are shown to be large for CH₄, but not for CO₂ and other small spherical adsorbates, in ZIF-8.
11
Breen, Gary Francis. "Novel materials showing nonlinear optical behaviour." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316594.
Full text
12
Yu, Howard. "Spin Dynamics in Novel Materials Systems." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1435582765.
Full text
13
Esfandiarfard, Keyhan. "Novel Organophosphorus Compounds for Materials and Organic Synthesis." Doctoral thesis, Uppsala universitet, Molekylär biomimetik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-328295.
Full textAbstract:
This thesis is devoted to the development of new organophosphorus compounds for potential uses in material science and as reagents in Organic Chemistry. Organophosphorus compounds in a single molecule or organic electronics context are appealing as the phosphorous centers perturb the electronic properties of the π-conjugated systems while at the same time provide synthetic handles for subsequent synthetic modifications. As such, new synthetic methodology to such compounds and the exploration of new building blocks is of considerable interest. In a different study, novel organophosphorus compounds are synthesized and shown to promote a reaction in Organic Chemistry that has previously not been possible, i.e. the stereoselective reductive coupling of aldehydes to alkenes. Such developments enlarge the toolkit of reactions that are available to Organic Chemists, and may impact the synthetic routes to pharmaceuticals and other important commodity chemicals. A general introduction of the key structural unit of this thesis, phosphaalkenes, is given in the first chapter. The synthesis, reactivity, properties and applications of these P=C double bond containing compounds are highlighted. The Wittig reaction and its variations as well as the phosphorus analogues that produce phosphaalkenes are outlined in detail. The second chapter is dedicated to the synthesis of a precursor that is used for the preparation of novel π-conjugated, organophosphorus compounds. C,C-Dibromophosphaalkenes are prepared and the halide substituents are used for the selective introduction of acetylene units. Besides the phosphaalkenes, the successful syntheses of two new diphosphenes is presented, indicating a broad applicability of the precursors. The third chapter is dedicated to the isolation of a metal-free phosphanylphosphonate that transforms aldehydes quantitatively to their corresponding E-phosphaalkenes in a transition metal-free phospha-HWE (Horner-Wadsworth-Emmons) reaction. The reaction benefits from mild conditions, high E-stereoselectivity, and a broad substrate scope. In the last chapter, a novel method for the reductive coupling of aldehydes to olefins is introduced. The reaction, which is a vast improvement over the McMurry coupling, allows for the selective synthesis of symmetrical and most importantly unsymmetrical E-alkenes. The phosphanylphosphonate mentioned above is the reagent that facilitates the coupling of the aldehydes via a phosphaalkene intermediate. This one-pot reaction benefits from mild conditions, good conversions, and high E-stereoselectivity. In summary, the thesis presents novel aspects of organophosphorus chemistry. These include the preparations and exploration of interesting precursors for the construction of π-conjugated organophosphorus compounds, and the use of organophosphorus reagents for unprecedented transformations in Organic Chemistry.
14
Thompson, Joshua A. "Evaluation and application of new nanoporous materials for acid gas separations." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/48983.
Full textAbstract:
Distillation and absorption columns offer significant energy demands for future development in the petrochemical and fine chemical industries. Membranes and adsorbents are attractive alternatives to these classical separation units due to lower operating cost and easy device fabrication; however, membranes possess an upper limit in separation performance that results in a trade-off between selectivity (purity) and permeability (productivity) for the target gas product, and adsorbents require the need to be water-resistant to natural gas streams in order to withstand typical gas compositions. Composite membranes, or mixed-matrix membranes, are an appealing alternative to pure polymeric membrane materials by use of a molecular sieve “filler” phase which has higher separation performance than the pure polymer. In this thesis, the structure-property-processing relationships for a new class of molecular sieves known as zeolitic imidazolate frameworks (ZIFs) are investigated for their use as the filler phase in composite membranes or as adsorbents. These materials show robust chemical and thermal stability and are a promising class of molecular sieves for acid gas (CO₂/CH₄) separations. The synthesis of mixed-linker ZIFs is first investigated. It is shown that the organic linker composition in these materials is controllable without changing the crystal structure or significantly altering the thermal decomposition properties. There are observable changes in the adsorption properties, determined by nitrogen physisorption, that depend on the overall linker composition. The results suggest the proposed synthesis route facilitates a tunable process to control either the adsorption or diffusion properties depending on the linker composition. The structure-property-processing relationship for a specific ZIF, ZIF-8, is then investigated to determine the proper processing conditions necessary for fabricating defect-free composite membranes. The effect of ultrasonication shows an unexpected coarsening of ZIF-8 nanoparticles that grow with increased sonication time, but the structural integrity is shown to be maintained after sonication by using X-ray diffraction, Pair Distribution Function analysis, and nitrogen physisorption. The permeation properties of composite membranes revealed that intense ultrasonication is necessary to fabricate defect-free membranes for CO₂/CH₄ gas separations. Finally, the separation properties of mixed-linker ZIFs is investigated by using adsorption studies of CO₂ and CH₄ and using composite membranes with differing linker compositions. Adsorption properties of mixed-linker ZIFs reveal that these materials possess tunable surface properties, and a selectivity enhancement of six fold over ZIF-8 is observed with mixed-linker ZIFs without changing the crystal structure. Gas permeation studies of composite membranes reveal that the separation properties of mixed-linker ZIFs are different from their parent frameworks. By proper selection of mixed-linker ZIFs, there is an overall improvement of separation properties in the composite membranes when compared to ZIF-8.
15
Marsden, Sean D. "Synthesis and characterisation of novel electronic materials." Thesis, Sheffield Hallam University, 1990. http://shura.shu.ac.uk/20015/.
Full textAbstract:
-4Scm-1 whereas the hexamethyl was insulating. This was proposed to be due to differing stacking characteristics. The properties of the ternary salts were proved to be intrinsic and not solvent induced. The failure of the amphiphilic dipyrrylmethene to complex with TCNQ was proposed to be due to steric hindorance which encumbers the close approach of the TCNQ. The Langmuir film of the dipyrrylmethene was shown to undergo re-orientation on the subphase. The L-B film of a picolinium TCNQ charge transfer salt was shown not to under go a molecular re-orientation due to the increase in the area of the hydrophobic aliphatic chains.
16
Gebbie, James Thomas. "A theoretical study of crystal growth in nanoporous materials using the Monte Carlo method." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/a-theoretical-study-of-crystal-growth-in-nanoporous-materials-using-the-monte-carlo-method(d601decf-d422-42a5-b13a-dbc1e5dabf99).html.
Full textAbstract:
This work is aimed at understanding the underlying processes of crystal growth in nanoporous materials at the molecular level utilising computational modelling. The coarse grain Monte Carlo program constructed over a number of works at the CNM has shown success in modelling cubic zeolite systems. The goal of this work is to adapt the program to deal with the complexities of a wide range of different crystal systems. There have been many studies of crystal growth and many problems solved. In zeolites, however, there are still a lot of questions to answer. Growth rates and activation energies for crystal growth processes in zeolites are some of the things that remain unsolved for zeolites. Coarse grain Monte Carlo modelling simplifies the problem and can provide an insight into the underlying processes that govern crystal growth. This study focused its energetics around the formation of stable closed cage surface structures deduced from careful study of the dissolution of zeolite L terraces. Two approaches from an energetic point of view were investigated during the course of this study. The first considered the energetics from an energy of attachment point of view whilst the second focused on the energy of destabilisation with respect to crystal bulk. In this study the crystal growth of the following systems were probed computationally: LTA, SOD, LTL, ERI, OFF. Both zeolite and MOF crystal systems were studied over the course of this work. The algorithm developed in study shows some potential in being able to give insight to experimental crystal growth chemists as to how changing the rates of growth of certain cage structures would affect the overall morphology of the crystal grown. They can then utilise their knowledge of how using certain cations or templates, for example, can alter the stabilisation of certain cage structures to in effect design crystals of desired properties.
17
Shen, Xiangqian. "Novel processing routes for oxide cathode emission materials." Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/10822.
Full textAbstract:
An investigation has been carried out into the production of the alkaline earth carbonate and oxide powders and coatings suitable as cathode emission materials by the ethylenediaminetetraacetic acid (EDT A) gel method for potential application as cathode emission materials. The emission performance of thermionic cathodes coated with these materials has been measured, and found to give encouraging results, comparable with conventionally prepared oxide emission materials, despite the former having not been optimised. Amorphous gels of composition Ca-EDTA, Sr-EDTA, Ba-EDTA, [SrO.5 Bao.5J-EDTA and [SrO.5 Bao.5 Cao.05J-EDTA were successfully prepared from aqueous solutions of alkaline earth nitrates and EDT A. Subsequently, the thermal decomposition of the gels and the effects of temperature and atmospheres on the decomposition have been studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The gels and the powders derived from calcination of these gels at different temperatures have been characterised by Fourier transform infrared spectroscopy (FTIR) , X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) with X-ray energy dispersive (EDX) spectroscopy. Coatings prepared by dip-coating, spraying and electrophoretic deposition (EPD) from the EDT A-sols have been characterised by FTIR, XRI> and SEM techniques. In addition, an attempt was made to study the coating of the colloidal particles in the suspension of methanolethanediol- EDTA sol by electrochemical impedance spectroscopy.
18
Howell, Owen Torridon. "Structure property relations of novel liquid-crystalline materials." Thesis, University of Southampton, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359197.
Full text
19
Mu, Bin. "Synthesis and gas adsorption study of porous metal-organic framework materials." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41097.
Full textAbstract:
Metal-organic frameworks (MOFs) or porous coordination polymers (PCPs) have become the focus of intense study over the past decade due to their potential for advancing a variety of applications including air purification, gas storage, adsorption separations, catalysis, gas sensing, drug delivery, and so on. These materials have some distinct advantages over traditional porous materials such as the well-defined structures, uniform pore sizes, chemically functionalized sorption sites, and potential for post-synthetic modification, etc. Thus, synthesis and adsorption studies of porous MOFs have increased substantially in recent years. Among various prospective applications, air purification is one of the most immediate concerns, which has urgent requirements to improve current nuclear, biological, and chemical (NBC) filters involving commercial and military purposes. Thus, the major goal of this funded project is to search, synthesize, and test these novel hybrid porous materials for adsorptive removal of toxic industrial chemicals (TICs) and chemical warfare agents (CWAs), and to install the benchmark for new-generation NBC filters. The objective of this study is three-fold: (i) Advance our understanding of coordination chemistry by synthesizing novel MOFs and characterizing these porous coordination polymers; (ii) Evaluate porous MOF materials for gas-adsorption applications including CO2 capture, CH4 storage, other light gas adsorption and separations, and examine the chemical and physical properties of these solid adsorbents including thermal stability and heat capacity of MOFs; (iii) Evaluate porous MOF materials for next-generation NBC filter media by adsorption breakthrough measurements of TICs on MOFs, and advance our understanding about structure-property relationships of these novel adsorbents.
20
Griffiths, Jon-Paul. "Synthesis of novel organic materials with electrical conducting properties." Thesis, Nottingham Trent University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415118.
Full text
21
Pang, Hao. "Synthesis, structure and properties of novel organic electroactive materials." Thesis, University of Strathclyde, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501889.
Full text
22
Fung, Y. W. F. "The synthesis of novel organic materials for radiation detection." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599266.
Full textAbstract:
The aim of the project is to synthesise organic materials to allow for efficient and reproducible quantification of radiation doses. The measurement should be simple, and be able to be read out immediately. In one approach, highly fluorescent organic materials, especially conjugated materials, would be used as radiation detectors. The polymer films will be designed to produce quenching centres upon irradiation; therefore the loss of fluorescence will give an accurate measurement of the total radiation dose received. Another method is to measure the conductivity of the material before and after radiation exposure. A sensitiser or radiaolabile dopant to enhance response may also be necessary. Here, iodine-containing compounds and onium salts were used. Iodine-containing compounds are expected to produce iodine upon irradiation. Onium salts are used as photoinitiators for polymerisations, producing acid species upon irradiation. Both acids and iodine can then act as dopants for conjugated polymers, resulting in quenching of fluorescence and increases in conductivity. A wide variety of materials were synthesised for evaluation. These included iodinated conjugated polymers, sulphonium and iodonium salts. A novel fluorescent diacetylene was also synthesised as well as several known polymers such as MEH-PPV, PHT and poly(3-BCMU). The effects of visible light on these materials, as well as blends were looked at, and some novel effects found. In particular, the photosensitisation and subsequent doping of MEH-PPV with onium salts was discovered.
23
Blomdahl, Emil. "Synthesis and characterization of novel hybrid organic-inorganic materials." Thesis, KTH, Tillämpad fysikalisk kemi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-302288.
Full textAbstract:
Efterfrågan på bättre och mer hållbart material ökar. Mer effektivt material kommer att behövas för att möta den ökande, globala efterfrågan. Hybrida organiska-oorganiska material är en typ av material som har varit av stort intresse nyligen, och kan beskrivas som en typ av material som består av både organiska och oorganiska komponenter. Denna avhandling har fokuserat på hybrida organiska-oorganiska material inspirerade av den klassiska perovskitstrukturen ABX3, där komponent A är en organisk katjon, komponent B är en divalent metalkatjon och komponent X är en anjon. Hybrida organiska-oorganiska material som är utgår från den klassiska perovskitstrukturen kan ha olika funktionella egenskaper och en bred variation av tänkbara applikationer. Några exempel på dessa egenskaper och möjliga applikationer inkluderar god fotokonduktivitet för solceller, utmärkt emissionsegenskaper för ljusdioder och justerbara dielektriska egenskaper för elektroniska växlar och sensorer. De fysiska egenskaperna av det hybrida organiska-oorganiska materialet beror på kristallstrukturen av materialet, som i sig bestäms av valet av komponenter. På grund av de många möjligheter av organiska och oorganiska komponenter så finns det möjlighet att syntetisera helt nya hybrida organiska-oorganiska föreningar som kan ha nya eller förbättrade fysiska egenskaper. Nuvarande hybrida organiska-oorganiska material som utgår från perovskitstrukturen använder huvudsakligen bly som divalent metalkatjon, och det beror på att den ger den bästa funktionella effekten. Blys toxicitet är dock en stor nackdel för nuvarande blybaserade hybrid oorganiska material. Möjligheten att ersätta bly med en annan divalent metall har undersökts under detta projekt. I denna avhandling så har den organiska katjonen cyclohexylammonium (CHA) varit i fokus som den organiska komponenten. Målet med detta examensarbete var att designa, syntetisera och karakterisera nytt hybrid organisk-oorganiskt material. De hybrida organiska-oorganiska föreningarna CHAZnBr3 och (CHA)2ZnBr4 syntetiserades för den första gången, så vitt författaren vet, och kommer vara i fokus i denna avhandling. De två nya hybrida organiska-oorganiska föreningarna blev strukturellt karakteriserade med X-ray Diffraction (XRD) och termiskt karakteriserade med Thermal Gravimetric Analysis (TGA) och Differential Scanning Calorimetry (DSC). Den första föreningen, CHAZnBr3, kunde bestämmas att vara ortorombisk vid 298 K. Föreningen bestämdes vara termisk stabil upp till 490 K, och genomgår en fasövergång vid 445 K. Den andra föreningen, (CHA)2ZnBr4, kunde inte bestämmas strukturellt vid varken 100 K eller 298 K. Föreningen bestämdes vara termisk stabil upp till 490 K, och genomgår en fasövergång vid 230 K. Ytterligare karakterisering krävs för att bättre förstå egenskaperna hos dessa föreningar och deras möjliga användningsområden.The demand for better and more sustainable material is increasing. More efficient materials will be needed to meet the growing global need. Hybrid organic-inorganic materials are one type of materials that have been of great interest recently, which can be described as a class of materials that mix organic and inorganic components. This thesis focused on hybrid organic-inorganic materials inspired by the classical perovskite crystal structure ABX3, where component A is an organic cation, component B is a divalent metal cation and component X is an anion. Hybrid organic-inorganic materials based on the classical perovskite structure may have various functional properties and may have a broad range of potential applications. Some examples of those properties as well as some and possible applications include good photoconductivity and power conversion efficiency for photovoltaic devices, excellent emission properties for light emitting diodes and tunable dielectric properties for electronic switches and sensors. The physical properties of the hybrid organic-inorganic material are determined by the crystal structure of the material, which in turn will be decided by the choice of components. With the many possible choices for organic and inorganic components, there is an opportunity to synthesize completely new hybrid organic-inorganic compounds that may display new or superior physical properties. Current hybrid organic-inorganic materials based on the perovskite crystal structure mainly use lead as the divalent metal, since it currently gives the best performance. The toxicity of lead is a major drawback for current lead-based hybrid organic-inorganic materials. The possibility to replace lead with another divalent metal has been explored during this project. For this thesis, the organic cation cyclohexylammonium (CHA) has been of focus as the organic component. The aim of this thesis was to design, synthesize and characterize novel hybrid organic-inorganic compounds. The hybrid organic-inorganic compounds CHAZnBr3 and (CHA)2ZnBr4 were synthesized for the first time, to the best of our knowledge, and will be the focus of this thesis. The two new hybrid organic-inorganic compounds were structurally characterized by X-ray Diffraction (XRD) and thermally characterized by Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The first compound, CHAZnBr3, could be determined to be orthorhombic at 298 K. The compound was found to be thermally stable up 490 K, and to undergo a phase transition at 445 K. The second compound, (CHA)2ZnBr4, could not be fully structurally solved at either 100 K or 298 K. The compound was found to be thermally stable up to 490 K, and to undergo a phase transition at 230 K. Further characterization will be needed to better understand the properties of these two compounds and their possible applications.
24
Smith, Brendan Derek. "A novel approach to the scalable production of nanoporous silicon membranes for applications in water and energy." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/117935.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2018.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 125-138).
This thesis introduces two chemical etching-based methods for the production of nanoporous silicon, improving on current state-of-the-art fabrication strategies in terms of scalability and simplicity. The developed processes also allow for new opportunities with respect to pore size, pore aspect ratio, and large-scale homogeneity. The first approach utilizes solution-casting of core-shell nanoparticle catalysts, where the shell is employed as a sacrificial spacer layer to maintain separation between etching-active catalyst cores. A second technique utilizing sputter-deposition of catalyst is developed with the goal of improving process scalability and homogeneity. With no intrinsic limitations on substrate size, this approach is used to produce nanoporous silicon over areas larger than 25 cm 2, pores less than 5 nm in diameter, and aspect ratios greater than 1000:1. Post-etch modification of the nanoporous silicon is performed by atomic layer deposition of alumina, titania, and tungsten nitride onto the surface and pore walls of the porous silicon, highlighting its morphological and chemical tunability. Utility of the material is demonstrated via its implementation in three industrially relevant use cases. As a nanofiltration membrane the material exhibits a size-cutoff as low as 2 nm, and tunable thickness-dependent permeability ranging over three orders of magnitude. Additionally, it demonstrates promise as an active material in a thermoelectric device, reducing thermal conductivity by approximately 70 fold with respect to bulk silicon, of which a factor of 20 can be attributed directly to the porosity in the film. Finally, applicability to the patterning of 2D materials is demonstrated using centimeter scale nanoporous silicon masks in the dry etching of molybdenum disulfide and tungsten disulfide, producing porous structures on the nanoscale. The broad impact of this work is the introduction of two new strategies for the manufacturing of nanoporous silicon at scale, and introduction of the relevant design metrics for control of pore size, pore aspect ratio, and homogeneity of the material. It is expected that this knowledge will be of use in applications which stand to benefit from the introduction of this unique form of nanoporous silicon.
by Brendan Derek Smith.
Ph. D.
25
Webster, R. "Approaches to novel materials based on poly(diazo)-compounds." Thesis, University of Liverpool, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317292.
Full text
26
Chanut, Nicolas. "Using external factors to improve gas adsorption in nanoporous materials : control of humidity and mechanical pressure." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4743.
Full textAbstract:
L'augmentation du niveau de CO2 atmosphérique est un sujet de préoccupation publique notoire. Afin d'atténuer son impact sur l'environnement, il est urgent de réduire les émissions de CO2 d’origines anthropiques. Une méthode considérée comme viable est la capture de CO2 par des procédés d’adsorption en utilisant une classe émergente de matériaux, les Metal-Organic Frameworks (MOFs). A ce jour, l’évaluation des MOFs s’est principalement axée sur leurs performances de séparation (capacité, sélectivité et régénération). Cependant, des facteurs externes peuvent influer sur les performances globales des procédés. L’objectif de cette thèse est d’évaluer trois d’entre eux : la présence de vapeur d’eau dans les effluents gazeux, l’effet de la mise en forme des matériaux et l’effet d’une pression mécanique externe sur les performances d’adsorption de gaz. Il est montré que ces facteurs externes peuvent être utilisés pour améliorer les performances des procédés dans des conditions spécifiquesThe increase in atmospheric CO2 level is a notorious matter of public concern. To mitigate its impact on the environment, it is urgent to reduce emissions of anthropogenic CO2. A method considered by many as a viable option is CO2 capture by adsorption using an emerging class of materials, the Metal-Organic Frameworks (MOFs). To date, evaluation of MOFs has been mainly focused on the separation performance of the material looking at the capacity, selectivity and regeneration capability. However external factors can influence the overall performances of processes turning to industrial applications. The purpose of this thesis was to evaluate three of them: the presence of water vapor in post-combustion flue gases, the effect of shaping powders into pellets form and the effect of an external mechanical pressure on gas adsorption performance. Unexpectedly, it is shown that these external factors could be used to improve process performances under specific conditions
27
Brunet, Gabriel. "Molecular Engineering of Metal-Organic Assemblies: Advances Toward Next Generation Porous and Magnetic Materials." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40385.
Full textAbstract:
The controlled assembly of molecular building blocks is an emerging strategy that allows for the preparation of materials with tailor-made properties. This involves the precise combination of molecular subunits that interact with one another via specifically designed reactive sites. Such a strategy has produced materials exhibiting remarkable properties, including those based on metal-organic frameworks and single-molecule magnets. The present Thesis aims to highlight how such metal-organic assemblies can be engineered at the molecular level to promote certain desired functionalities. Specifically, Chapter 2 will focus on the confinement effects of a crystalline sponge on a ferrocene-based guest molecule that is nanostructured within the porous cavities of a host material. In doing so, we evaluate how one can exert some level of control over the binding sites of the guest molecule, through the addition of electron-withdrawing groups, as well as tuning the physical properties of the guest itself through molecular encapsulation. Notably, we demonstrate a distinct change in the dynamic rotational motion of the ferrocene molecules once confined within the crystalline sponge. In Chapter 3, we investigate the generation of slow relaxation of the magnetization from a Co(II)-based metal-organic framework. We compare this to a closely related 2D Co(II) sheet network, and how slight changes in the crystal field, probed through computational methods, can impact the magnetic behaviour. This type of study may be particularly beneficial in the optimization of single-ion magnets, by sequestering metal centres in select chemical environments, and minimizing molecular vibrations that may offer alternative magnetic relaxation pathways.
We extend these principles in Chapter 4, through the use of a nitrogen-rich ligand that acts as a scaffold for Ln(III) ions, thereby yielding 0D and 1D architectures. The coordination chemistry of Ln(III) ions with N-donor ligands remains scarce, especially when evaluated from a magnetic perspective, and therefore, we sought to determine the magnetic behaviour of such compounds. The monomeric unit displays clear single-molecule magnet behaviour with an energetic barrier for the reversal of the magnetization, while the 1D chain displays weaker magnetic characteristics. Nevertheless, such compounds incorporating nitrogen-rich ligands offer much promise in the design of environmentally-friendly energetic materials. In Chapter 5, we take a look at different two different systems that involve the formation of radical species. On one hand, we can promote enhanced magnetic communication between Ln(III) ions, which is typically quite challenging to achieve given the buried nature of the 4f orbitals, and on the other hand, we rely on a redox-active ligand to design stimuli-responsive metal-organic assemblies. The latter case provides access to “smart” molecular materials that can respond to changes in their environment. Here, a multi-stimuli responsive nanobarrel was studied, which displayed sensitivity to ultraviolet radiation, heat and chemical reduction.
Lastly, Chapter 6 provides a new method for the systematic generation of cationic frameworks, termed Asymmetric Ligand Exchange (ALE). This strategy focuses on the replacement of linear dicarboxylates with asymmetric linkers that features one less negative charge, in order to tune the ionicity of porous frameworks. This allows for the retention of the structural topology and chemical reactivity of the original framework, representing distinct advantages over other similar strategies. Methods to retain permanent porosity in such cationic frameworks are also proposed. Altogether, these studies highlight how the directed assembly of ordered networks can generate varied properties of high scientific interest.
28
Wahl, Helene. "Development of novel supramolecular framework materials based on organic salts." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/95858.
Full textAbstract:
Thesis (PhD)--Stellenbosch University, 2014.ENGLISH ABSTRACT: The aim of the work presented in this thesis was to design ionic organic framework materials based on carboxylate salts with the intention of engineering interesting properties, such as porosity, into these framework materials. The first section focuses on the characterisation and porosity studies of an ionic framework material, 3,4-lutidinium pamoate hemihydrate, with THF-filled channels in the solid state. It was shown that this framework is able to exchange the THF in the channels for a wide variety of compounds, with many of these exchanges occurring in a single-crystal to single-crystal fashion. Competition experiments conducted with the framework, both by immersing crystals of the framework in solvent mixtures, as well as by exposing crystals of the framework to mixtures of solvent vapours, indicated that it is able to selectively exchange for one guest over another. The kinetics of exchange of this framework were studied, and it was possible to identify a kinetic model describing this process. A second novel framework-type material, 4-phenylpyridinium pamoate, was identified during the course of this study, as well as five isostructural frameworks containing different guest molecules. In this case the framework consists of discrete units that close-pack in such a way that guest molecules are included in constricted cavities in the solid state. Although this framework-type material is not porous, it is thermally quite stable and also highly selective. It is able to selectively encapsulate 1,4-dioxane when crystallised from various solvent combinations including 1,4-dioxane. In addition, eight novel structures with pamoic acid in combination with various pyridyl derivatives were obtained. A third novel framework material was obtained with N,N'-bis(glycinyl)pyromellitic diimide in which, due to the extended hydrogen-bonded network formed between the constituents of the framework, DMF molecules are aligned in channels. It was found that this framework material can also be formed by mechanochemical synthesis, and investigation of the thermal behaviour of this framework showed that it has the potential to be porous, since the framework appears to remain intact after desolvation. Furthermore, six novel structures with N,N'- bis(glycinyl)pyromellitic diimide in combination with various N-heterocycles were obtained. All structures obtained in this study were also further analysed to determine whether there are particular structural features that are required for framework formation. Insights gained from these investigations, in terms of degree of ionisation of the anion, packing arrangements and hydrogen bonding patterns as well as the molecular shape of the components are discussed.
AFRIKAANSE OPSOMMING: Die doel van die werk wat in hierdie tesis voorgelê word is om ioniese organiese raamwerkmateriale gebaseer op karboksilaatione te ontwerp, met die voorneme om interessante eienskappe in hierdie materiale te bewerkstellig. Die eerste afdeling fokus op die karakterisering en porositeit van ‘n ioniese organiese raamwerkmateriaal, 3,4-lutidiniumpamoaathemihidraat, wat kanale gevul met tetrahidrofuraan (THF) besit. Dit is aangetoon dat dit moontlik is vir hierdie raamwerkmateriaal om die THF in die kanale te verruil vir ‘n wye verskeidenheid stowwe, waarvan baie van hierdie uitruilings geskied as ‘n enkelkristal tot enkelkristal transformasie. Kompetisie-eksperimente is met hierdie raamwerkmateriaal uitgevoer deur die kristalle in mengsels van oplosmiddels te onderdompel, sowel as deur die kristalle aan mengsels van die oplosmiddeldampe bloot te stel. Die resultate het aangedui dat dit moontlik is vir hierdie raamwerkmateriaal om een gasstof selektief teenoor ‘n ander te verruil vir die THF in die kanale. Die kinetika van die uitruilingsproses van hierdie materiaal is ook bestudeer en dit was moontlik om ‘n kinetiese model te identifiseer wat die uitruilingsproses beskryf. ‘n Tweede nuwe raamwerk-tipe materiaal, 4-fenielpiridiniumpamoaat, is deur die loop van hierdie studie geïdentifiseer, sowel as vyf isostrukturele raamwerkmateriale waarvan net die gasstof verskil. In hierdie geval bestaan die raamwerk uit diskrete eenhede wat op so ‘n wyse saampak dat die gasstowwe in vernoude porieë ingesluit word. Alhoewel hierdie raamwerk-tipe materiaal nie poreus is nie, is dit termies stabiel en ook hoogs selektief. Die raamwerkmateriaal kan selektief 1,4-dioksaan enkapsuleer wanneer dit gekristalliseer word vanuit ‘n verskeidenheid oplosmiddel kombinasies met 1,4-dioksaan. Verder is agt nuwe strukture verkry met die pamoaat ioon in kombinasie met ‘n verskeidenheid piridien-derivate. ‘n Derde nuwe raamwerkmateriaal is verkry met N,N'-bis(glisiniel)piromellitiese diïmied waarin, danksy die uitgebreide waterstofgebinde netwerk tussen die komponente van die raamwerk, die DMF molekules in kanale aangetref word. Hierdie raamwerkmateriaal kan deur meganochemiese sintese berei word en verdere ondersoek na die termiese gedrag van hierdie raamwerkmateriaal dui aan dat dit die potensiaal het om porositeit te toon, aangesien die raamwerk behoue bly nadat die DMF molekules verwyder is. Ses nuwe strukture is ook met N,N'-bis(glisiniel)piromellitiese diïmied in kombinasie met ‘n wye verskeidenheid stikstof-bevattende heterosikliese verbindings verkry. Alle strukture wat tydens hierdie studie verkry is, is verder ondersoek om te bepaal of daar spesifieke strukturele kenmerke is wat benodig word vir die vorming van raamwerkmateriale. Insigte wat verkry is vanuit hierdie ondersoeke, in terme van die graad van ionisasie van die anioon, die rangskikking van molekules in die struktuur en waterstofbindingspatrone, sowel as die molekulêre vorm van die komponente, word bespreek.
29
Omar, Ozma. "Optical effects in Langmuir-Blodgett films of novel organic materials." Thesis, Sheffield Hallam University, 1998. http://shura.shu.ac.uk/20143/.
Full textAbstract:
The high level of molecular control makes the Langmuir-Blodgett (LB) technique an appealing method of film deposition. The uniform nature of the films produced allows convenient investigation of intermolecular interactions and provides information pertaining to the orientation of molecules within films. LB films of two amphiphilic materials with contrasting molecular structures have been deposited. AmPc5 (a metal-free phthalocyanine (pc)) is a two-dimensional, cyclic molecule, whereas AmAzl (a resorcinol calixarene) possesses a three-dimensional basket-type structure. The amphiphilic nature of both molecules is as a result of functional side-chains. The AmPc5 spreading solution was prepared by dissolving in trichloroethane to a concentration of 0.1 mg/ml. After spreading 500-600 ul, the resulting Langmuir film was found to have a critical pressure of 28 mN/m and an area per molecule of 1.61 nm2 on the water surface. Monolayer deposition onto glass substrates enabled spectroscopic examination of the films and comparison to solution spectra. The solution spectrum shows the split Q-band absorption peaks at 700 nm and 733 nm characteristic of metal-free pc's. The LB film spectrum shows a broadening of both peaks and a red shift of the 733 nm peak, and a blue shift of the 700 nm peak. The 700 nm peak is suppressed as a result of the stack-like packing structure of AmPc5. Absorption spectra of floating AmPc5 monolayers imply that the material does not assume the monomer state at any stage of compression. This is characteristic of rigid molecules that induce order within the floating monolayer. The refractive indices (n) and extinction coefficients (k) were determined across the visible wavelength range. Both the n and k values are shown to increase with monolayer thickness, although the n value tends towards a steady value of 2.1. Deposition onto gold coated glass substrates enabled surface plasmon resonance analysis and determination of n and k at specific film thickness'. The n was found to increase with film thickness, tending towards a steady state value of 2.0. This is in excellent agreement with spectroscopic analysis. Absorption spectra measured using polarised light show AmPc5 exhibits dichroism. The calculations indicate that the pc ring lies almost perpendicular to the substrate. AmAzl was dissolved in chloroform to a concentration of 0.5 mg/ml with 10% ethanol to aid solubility. The optimum solution spreading quantity required to form a floating monolayer was found to be between 50 and 100 ul. The film was shown to have a critical pressure of 30 mN/m and an area per molecule of 1.86 nm2 on the water surface. Both LB film and solution spectra show a single absorbance peak at 454 nm which is due to transitions in the azo functional side chains. Calculation of n and k shows that they tend towards steady values of 1.5 and 2.0, respectively. The n obtained via surface plasmon resonance analysis shows a steady state value of 1.43 on silver coated glass and 1.35 on gold coated glass. This suggests a different type of packing structure on all three substrates. The lack of dichroism exhibited by AmAzl indicates the formation of in-plane amorphous films. AmAzl was deposited in alternating layers with tricosenoic acid. The structure was confirmed by X-ray diffraction studies and investigated using second harmonic generation. The second harmonic signal was shown to be proportional to the square of the number of bilayers.
30
Ebenhoch, Bernd. "Organic solar cells : novel materials, charge transport and plasmonic studies." Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/7814.
Full textAbstract:
Organic solar cells have great potential for cost-effective and large area electricity production, but their applicability is limited by the relatively low efficiency. In this dissertation I report investigations of novel materials and the underlying principles of organic solar cells, carried out at the University of St Andrews between 2011 and 2015. Key results of this investigation: • The charge carrier mobility of organic semiconductors in the active layer of polymer solar cells has a rather small influence on the power conversion efficiency. Cooling solar cells of the polymer:fullerene blend PTB7:PC₇₁BM from room temperature to 77 K decreased the hole mobility by a factor of thousand but the device efficiency only halved. • Subphthalocyanine molecules, which are commonly used as electron donor materials in vacuum-deposited active layers of organic solar cells, can, by a slight structural modification, also be used as efficient electron acceptor materials in solution-deposited active layers. Additionally these acceptors offer, compared to standard fullerene acceptors,advantages of a stronger light absorption at the peak of the solar spectrum. • A low band-gap polymer donor material requires a careful selection of the acceptor material in order to achieve efficient charge separation and a maximum open circuit voltage. • Metal structures in nanometer-size can efficiently enhance the electric field and light absorption in organic semiconductors by plasmonic resonance. The fluorescence of a P3HT polymer film above silver nanowires, separated by PEDOT:PSS, increased by factor of two. This could be clearly assigned to an enhanced absorption as the radiative transition of P3HT was identical beside the nanowires. • The use of a processing additive in the casting solution for the active layer of organic solar cells of PTB7:PC₇₁BM strongly influences the morphology, which leads not only to an optimum of charge separation but also to optimal charge collection.
31
Walker, Wesley Thomas. "The design, synthesis, and characterization of novel electronic organic materials." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1835606731&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
Full text
32
Chen, Jianglong 1976. "Novel patterning techniques for manufacturing organic and nanostructured electronics." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/39552.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2007.Page 206 blank.
Includes bibliographical references.
Molecular organic semiconductors and nanometer size particles are two new classes of functional materials allowing fabrication of electronic devices on low-cost and large area substrates. Patterning these electronic materials requires the development of unconventional techniques, and the scientific understanding behind the manufacture processes. We introduce the first-generation Molecular Jet (MoJet) printing technique for vacuum deposition of evaporated thin films and apply it to the fabrication of high-resolution pixelated (800 ppi) molecular organic light emitting devices (OLEDs) based on aluminum tris(8-hydroxyquinoline) (Alq3), and the fabrication of pentacene based organic field effect transistors (OFETs) with narrow channel (15 gm) and asymmetric silver/gold contacts. Patterned printing of both organic and metal films is demonstrated, with the operating properties of MoJet-printed OLEDs and OFETs shown to be comparable with the performance of devices fabricated by conventional evaporative deposition through a metal stencil. This MoJet printing technique is reconfigurable for digital fabrication of arbitrary patterns with multiple material sets and a high print accuracy of better than 5gtm, and scalable to large area substrates.
(cont.) Analogous to the concept of "drop-on-demand" in Inkjet printing technology, MoJet printing is a "flux-on-demand" process and we show it capable of fabricating multi-layer stacked film structures, as needed for engineered organic devices. We present the concept and the applications of the second-generation MoJet printing technique. Using this technique, we demonstrate patterned molecular organic semiconducting thin films directly printed by a three-step local evaporative deposition, in conjunction with using the HP thermal InkJet printing technology. This MoJet printing technique can be applied to pattern solution-processable molecular organic thin films, providing flux-on-demand in an ambient environment. We develop an Inkjet assisted micro-contact printing technique for the patterning of colloidal semiconductor nanoparticles. Active OLEDs incorporated with a uniform thickness layer of colloidal nanoparticles are fabricated by using this Inkjet printing plus stamp transferring technique. The material usage efficiency is largely boosted. To our knowledge, these three novel patterning techniques presented in this study provide for the first time unprecedented capabilities for manufacturing organic and nanostructured electronic devices.
by Jianglong Chen.
Ph.D.
33
Arab, Pezhman. "DESIGNED SYNTHESIS OF NANOPOROUS ORGANIC POLYMERS FOR SELECTIVE GAS UPTAKE AND CATALYTIC APPLICATIONS." VCU Scholars Compass, 2015. http://scholarscompass.vcu.edu/etd/4045.
Full textAbstract:
Design and synthesis of porous organic polymers have attracted considerable attentions during the past decade due to their wide range of applications in gas storage, gas separation, energy conversion, and catalysis. Porous organic polymers can be pre-synthetically and post-synthetically functionalized with a wide variety of functionalities for desirable applications. Along these pursuits, we introduced new synthetic strategies for preparation of porous organic polymers for selective CO2 capture.
Porous azo-linked polymers (ALPs) were synthesized by an oxidative reaction of amine-based monomers using copper(I) as a catalyst which leads to azo-linkage formation. ALPs exhibit high surface areas of up to 1200 m2 g-1 and have high chemical and thermal stabilities. The nitrogen atoms of the azo group can act as Lewis bases and the carbon atom of CO2 can act as a Lewis acid. Therefore, ALPs show high CO2 uptake capacities due to this Lewis acid-based interaction. The potential applications of ALPs for selective CO2 capture from flue gas, natural gas, and landfill gas under pressure-swing and vacuum swing separation settings were studied. Due to their high CO2 uptake capacity, selectivity, regenerability, and working capacity, ALPs are among the best porous organic frameworks for selective CO2 capture.
In our second project, a new bis(imino)pyridine-linked porous polymer (BIPLP-1) was synthesized and post-synthetically functionalized with Cu(BF4)2 for highly selective CO2 capture. BIPLP-1 was synthesized via a condensation reaction between 2,6-pyridinedicarboxaldehyde and 1,3,5-tris(4-aminophenyl)benzene, wherein the bis(imino)pyridine linkages are formed in-situ during polymerization. The functionalization of the polymer with Cu(BF4)2 was achieved by treatment of the polymer with a solution of Cu(BF4)2 via complexation of copper cations with bis(imino)pyridine moieties of the polymer. BF4- ions can act Lewis base and CO2 can act as a Lewis acid; and therefore, the functionalized polymer shows high binding affinity for CO2 due to this Lewis acid-based interaction. The functionalization of the pores with Cu(BF4)2 resulted in a significant enhancement in CO2 binding energy, CO2 uptake capacity, and CO2 selectivity values. Due to high reactivity of bis(imino)pyridines toward transitions metals, BIPLP-1 can be post-synthetically functionalized with a wide variety of inorganic species for CO2 separation and catalytic applications.
34
Malan, Mareta. "Novel materials for VOC analysis." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71646.
Full textAbstract:
Thesis (MSc)--Stellenbosch University, 2012.ENGLISH ABSTRACT: The need to analyse and detect volatile organic compounds (VOCs) at trace levels has led to the development of specialized sample preparation techniques. The requirement for trace analysis of VOCs stems from the negative effects they have on the environmental and human health. Methods for the analysis of non-polar VOCs commonly found as trace contaminants in water and analysis of more polar oxygenated compounds commonly found in zero-VOC water-based paints were developed. Solid phase micro extraction (SPME) was employed and extraction of the majority of the target analytes could be achieved at levels below 0.3 μg.l-1. In an attempt to further improve the detection of these two target analyte groups, novel materials based on poly(dimethyl siloxane) (PDMS) were investigated as possible extraction phases for VOCs, with the focus specifically on the analysis of the polar analytes in paint. Conventional free radical polymerization was used to synthesize poly(methyl methacrylate-graft-poly(dimethyl siloxane) (PMMA-g-PDMS), poly(methacrylic acid)-graft-poly(dimethyl siloxane) (PMAA-g-PDMS), polystyrene-graftpoly( dimethyl siloxane) (PSty-g-PDMS) and poly(butyl acrylate)-graft–poly(dimethyl siloxane) (PBA-g-PDMS). These polymers have a copolymer functionality which presents a series of different polarities. The MMA-g-PDMS and MAA-g-PDMS as well as the homopolymers were electrospun into nanofibers. The low glass transition temperature and molecular weight of the PBAg- PDMS meant that this polymer could not be electrospun. Scanning electron microscopy (SEM) was used to study the fiber morphology of the electrospun fibers and the non-beaded fibers were further investigated. Polyacrylonitrile-graft-poly(dimethyl siloxane) (PAN-g-PDMS) previously synthesized and electrospun by another member of the group were also investigated for use as possible extraction material in volatile analysis. The thermal stability of the nanofibers at 200°C was studied using thermal gravimetric analysis (TGA). This property is important since after the target analytes are extracted using the nanofibers, elevated temperatures are used to thermally desorp the volatile analytes from the extraction materials prior to GC analysis. The PAN-g-PDMS, MMA-g-PDMS and PMMA showed no significant weight loss during thermal evaluation, however, it was observed that the PMMA and PMMA-g-PDMS nanofibers looses their nanostructure and that the PAN-g-PDMS nanofibers changes colour from white to yellow to rust brown. The polymers based on MAA showed weight losses of more than 10% after one hour of exposure to the elevated temperatures, but the nanostructure remained intact. The PAN-g-PDMS, PMAA-g-PDMS and PMAA nanofibers were evaluated as possible extraction materials for VOC analysis. The nanofibers were evaluated using a similar approach to that of stir bar sorptive extraction (SBSE). Headspace sorptive extraction (HSSE) using a commercially available PDMS stir bar and the novel materials were used to evaluate the extraction efficiency of the different materials. The optimized extraction method developed using SPME were employed for the extraction using the nanofibers and PDMS stir bar. It was noted that the nanofibers lose their extraction capabilities during the first extraction/desorption cycle possibly due to thermal degradation therefore each of the materials can only be used in a single extraction. The majority of the non-polar analytes were extracted using the nanofibers at levels of 500 μg.l-1, however it was noted that the commercially available SPME extraction materials and the PDMS stir bar had superior extraction efficiencies for the specific target analytes. In the evaluation of the nanofibers for extraction of the more polar oxygenated analytes it was noted that 2-Ethylhexylacrylate was the only analyte to be extracted by all of the materials. The PAN-g-PDMS extracted three of the four analytes at levels of 100 μg.l-1. At lower analyte concentrations of 10 μg.l-1 only two of the four acrylate compounds were detected using the PAN-g-PDMS nanofibers. Ethyl acrylate was not extracted by any of the novel materials, whereas in SPME using the CAR/PDMS fiber, the LOD was determined to be below 1 μg.l-1. Although these materials were not superior to the commercially available phases, this is only the case for the specific target analytes analyzed.
AFRIKAANSE OPSOMMING: Die behoefte vir die analiese van vlugtige organiese verbindings (VOS) op spoorvlak, het gelei tot die ontwikkeling van gespesialiseerde monster voorbereidingstegnieke. Die vereiste vir die spoor analiese van die VOS het ontstaan uit die negatiewe uitwerking wat hierdie stowwe het op die omgewing en menslike gesondheid. Metodes vir die analiese van nie-polêre VOS wat algemeen voorkom as spoorkontaminante in water en polêre suurstofryke verbindings wat algemeen voorkom in nul-VOS water-gebaseerde verf was ontwikkel. Soliede fase mikro-ekstraksie (SFME) was gebruik, en die ekstraksie van die meerderheid van die teikenstowwe kon gedoen word op vlakke laer as 0,3 μg.l-1. In 'n poging om die opsporing van hierdie twee teiken analietgroepe verder te verbeter, is nuwe materiale gebaseer op polidimetielsiloksaan (PDMS), ondersoek as moontlik ekstraksiefases vir VOS, met die fokus spesifiek op die analiese van die polêre stowwe in verf. ’n Konvensionele vrye radikaal polimerisasieproses was gebruik om poli (metiel- metakrilaat)-entpoli( dimetielsiloksaan) (PMMA-g-PDMS), poli(metakrilaatsuur)-ent–poli (dimetielsiloksaan) (PMAA-g-PDMS), polistireen-ent-poli(dimetielsiloksaan) (PSty-g-PDMS) en poli(butielakrilaat)- ent-poli(dimetielsiloksaan) (PBA-g-PDMS) te sintetiseer. Hierdie ko-polimere het 'n kopolimeer funksionaliteit wat 'n reeks van verskillende polariteite bied. Die MMA-g-PDMS en MAA-g-PDMS sowel as die homopolimere was ge-elektrospin in orde om nanovesels te vorm. Die lae glasoorgangstemperatuur en molekulêre gewig van die PBA-g-PDMS het beteken dat hierdie polimeer nie elektrospin kon word nie. Skandeerelektronmikroskopie (SEM) was gebruik om die veselmorfologie van die ge-elektrospinde vesels te bestudeer en die nanovesels wat ’n eweredige oppervlak gehad het, was verder ondersoek. Poliakrilonitriel-ent-poli(dimetielsiloksaan) (PAN-g- PDMS) wat voorheen gesintetiseer en ge-elektrospin was deur 'n ander lid van die groep is ook ondersoek vir gebruik as moontlik ekstraksiemateriaal vir die analiese van vlugtige stowwe. Die termiese stabiliteit van die nanovesels was by 200°C bestudeer met behulp van ‘n termiese gravimetriese analiese (TGA) instrument. Hierdie eienskap is belangrik, aangesien die teikenstowwe by hoë temperature van die nanovesels gedesorbeer word voor die GC-analiese. Die PAN-g-PDMS, MMA-g-PDMS en PMMA het geen beduidende gewigsverlies tydens termiese evaluering gehad nie, alhoewel dit egter waargeneem was dat die PMMA en PMMA-g-PDMS nanovesels hulle nanostruktuur verloor en dat die PAN-g-PDMS nanovesels se kleur verander van wit na geel na roesbruin gedurende die termiese analiese. Die polimere wat gebaseer was op MAA het ’n gewigs-verlies van meer as 10% getoon na 'n uur van blootstelling aan die verhoogde temperature, maar die nanostruktuur het ongeskonde gebly. Die PAN-g-PDMS, PMAA-g-PDMS en PMAA nanovesels was geëvalueer as moontlike ekstraksiemateriale vir VOS-analiese. Die nanovesels was geëvalueer met 'n soortgelyke benadering tot dié van “stir bar“ sorpsie ekstraksie (SBSE). Bo-ruimte sorpsie ekstrasie is gebruik om die ekstraksie-doeltreffendheid van die verskillende materiale (kommersiële PDMS en nanovesels) te evalueer. Die geoptimaliseerde ekstraksiemetode ontwikkel in SFME was gebruik vir die ekstraksie van die VOS met die nanovesels en die PDMS “stir bar“. Dit was waargeneem dat die nanovesels hul ekstraksievermoë verloor tydens die eerste ekstraksie/desorpsie siklus, moontlik as gevolg van termiese degradasie dus, kon die materiale slegs ‘n enkele maal gebruik word vir die ekstraksie. Die meerderheid van die nie-polêre stowwe was ge-ëkstraeer deur gebruik te maak van die nanovesels op vlakke van 500 μg.l -1, maar die kommersieel beskikbare SFME ekstraksie materiale en die PDMS “stir bar“ se ekstraksie-doeltreffendheid vir die spesifieke stowwe was beter. In die evaluering van die nanovesels vir die ekstraksie van die meer polêre suurstofryke stowwe was daar waargeneem dat 2- etielheksielakrilaat die enigste analiet was wat ge-ëkstraeer was deur al die materiale. Die PAN-g- PDMS kon drie van die vier polêre stowwe op vlakke van 100 μg.l-1 opspoor. By laer analietkonsentrasies van 10 μg.l-1 kon slegs twee van die vier akrilaat verbindings opgespoor word deur gebruik te maak van hierdie nanovesels. Etielakrilaat was nie ge-ëkstraeer deur enige van die nuwe materiale nie, terwyl in SFME met die gebruik van die CAR/ PDMS vesel, die analiet op vlakke onder 1 μg.l-1 opgespoor kon word. Alhoewel hierdie nuwe materiale nie beter is as die kommersieel beskikbare ekstraksiemateriale nie is dit net die geval vir die spesifieke teiken analietgroepe wat ondersoek was in hierdie studie.
35
Lao, Hongbai. "Novel microporous organo-clay materials and organo-clay polymeric composite membranes." Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/6830.
Full textAbstract:
A series of quaternarized ammonium mono and di-cations, quaternarized amino acid ester mono and di-cations, and quaternarized polyammonium cations were synthesized by methylation reaction. The synthesized quaternarized ammonium derivatives were incorporated into the interlamellar space of the smectites, montmorillonite (SWy-1) and hectorite (SHCa-1). The adsorption of these quaternarized ammonium cations by the smectites were studied by colorimetric and Na-electrode methods. Also the CEC values were determined from the adsorption isotherms and were found to be close to the CECs of the smectites. The intercalation of the quaternarized ammonium cations into the interlamellar space of the smectites were evaluated by X-ray powder diffraction technique and the changes of the interlayer spacings upon intercalation were measured. The adsorption and X-ray results indicated that the quaternarized ammonium cations adopt a parallel orientation arrangement in the interlamellar space of the smectites. Insight into the micropore structure of the prepared organo-smectites has been obtained with N$\sb2$ adsorption and desorption studies. The BET interlayer surface area, external surface area, micropore volume and mesopore volume were calculated from the N$\sb2$ adsorption and desorption isotherms. The total BET surface areas of the organo-smectites were in the range of 58-224 m$\sp2$/g, depending on the size of the intercalated cations. It has been implied that the incorporation of the quaternarized ammonium cations into the interlamellar space of the smectites results in a microporous material with a network of cavities whose height and volume are controlled by the size and the shape of the organic cation. The gas chromatographic properties of these organo-smectites have been determined with focus on the separation of air, CH$\sb4$ and CO$\sb2$ as well as the separation of C$\sb1$-C$\sb4$ and C$\sb5$-C$\sb8$ hydrocarbons. The organo-smectites have been proven to be a GC adsorbent for gas separations. The separation of methane and carbon dioxide was controlled by the interactions with the clay surface, not by the interaction with the substituents of the alkylammonium chain. The shapes of the microcavities played a role in the separation of gas mixtures. The CO$\sb2$ retention time has been found to increase with increasing the free surface area of the organo-smectite. Moreover, it has been shown that the retention time of C$\sb1$-C$\sb4$ hydrocarbons decreased with increasing the free volume of the organo-smectite. Furthermore, some microporous organo-smectite materials have been imbedded into the cross-linked polydimethylsiloxane (PDMS) polymers giving composite membranes. The composite membranes have been evaluated by the gas permeation experiments. The pure gas permeation results showed that the gas permeabilities decreased upon filling of the organo-smectites into the PDMS polymers. The pure gas permeability ratios of O$\sb2$/N$\sb2$ and CO$\sb2$/CH$\sb4$ were found to be controlled by both the organo-smectite content and the microporosity of the organo-smectites. The maximum pure gas permeability ratio for CO$\sb2$/CH$\sb4$ achieved was 8.7 as compared to 3.9 which was obtained for organo-smectite free PDMS membranes.
36
Sekizkardes, Ali Kemal PhD. "Pyrene-Derived Porous Organic Polymers: Design, Synthesis, and Application to Gas Storage and Separation." VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/3649.
Full textAbstract:
Porous organic polymers (POPs) received great attention in recent years because of their novel properties such as permanent porosity, adjustable chemical nature, and remarkable thermal and chemical stability. These attractive features make POPs very promising candidates for use in gas separation and storage applications. In particular, CO2 capture and separation from gas mixtures by POPs have been intensively investigated in recent years because of the greenhouse nature of CO2, which is considered a leading cause for global warming. CO2 chemical absorption by amine solutions from the flue gas of coal-fired power plants suffers from several challenges such as high-energy consumption in desorption, chemical instability, volatility, and corrosive nature, limiting the widespread use of this technology. To mitigate these limitations, new adsorbents with improved CO2 capturing properties need to be designed, synthesized, and tested. Alternatively, the use of cleaner fuels such as methane can reduce CO2 release or completely eliminates it in the case of hydrogen. However, the on-board storage of methane and hydrogen for automotive applications remains a great challenge.
With these considerations in mind, our research goals in this dissertation focus on the systematic design and synthesis of N-rich POPs and their use in small gas (H2 and CH4) storage as well as selective CO2 capture from gas mixtures. In particular, we have studied the effect of integrating pyrene and triazine building units into benzimidazole-linked polymers (BILPs) and covalent organic frameworks (COFs) on gas storage and separation. We have found that pyrene-based BILPs exhibit remarkable selective CO2 capturing capacities under industrial settings (VAS, PSA). However the methane and hydrogen storage capacities of BILPs were found to be only modest especially at high pressure due to their moderate surface area and pore volume. We addressed these limitations by the synthesis of a highly porous imine-linked COF (ILCOF-1), which has very high surface area and improved hydrogen and methane uptakes when compared to BILPs. We have demonstrated that the use of pyrene in BILPs and COFs can direct frameworks growth through - stacking and improve porosity and pore volume whereas the use of triazine is instrumental in improving the binding affinity of the frameworks towards CO2.
37
Barr, Jonathan (Jonathan Allan). "Evaluation of the commercial potential of novel organic photovoltaic technologies." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33621.
Full textAbstract:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2005.Includes bibliographical references (leaves 46-47).
Photovoltaic cells based on organic semiconducting materials have the potential to compete with the more mature crystalline and thin film based photovoltaic technologies in the future primarily due to the expectation of significantly reduced manufacturing costs. Stabilized power conversion efficiencies of organic photovoltaics are still well below those of crystalline Si photovoltaics, however a continuous, high throughput, roll-to-roll manufacturing process involving low temperature deposition or printing techniques is expected to partially account for their reduced efficiency and boost their commercial attractiveness. In addition, organic photovoltaics are flexible, light weight, and not fragile which makes them particularly suitable for transportation and portable electronics applications. Four organic photovoltaic technologies as well as the advantages and setbacks of each are described including Graetzel (wet) cells, blended photovoltaics, asymmetric tandem cells with hybrid planar-mixed molecular heterojunctions, and external antenna photovoltaics. A variety of start-up companies in various stages of commercialization of these technologies as well as the intellectual property related to these technologies is also discussed.
(cont.) A simplified cost model is presented to quantitatively estimate the possible cost reductions that continuous roll-to-roll production could entail for three different scenarios. Finally, a discussion of potential business strategies for licensing and commercializing organic photovoltaics is presented.
by Jonathan Barr.
M.Eng.
38
Chen, Rui. "HIGH PERFORMANCE SOLUTION-PROCESSED PEROVSKITE PHOTOVOLTAICS BY NOVEL MATERIALS." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1617818409646272.
Full text
39
Aleroh, Dickson. "Synthesis and characterization of novel low band gap semiconducting polymers for organic photovoltaic and organic field effect transistor applications." Thesis, Queen Mary, University of London, 2012. http://qmro.qmul.ac.uk/xmlui/handle/123456789/5272.
Full textAbstract:
This thesis describes the synthesis, characterization and device properties of a range of conjugated polymers incorporating 3,6-dilakylthieno[3,2-b]thiophene. We report a new and facile synthesis for the preparation of 3,6-dialkylthieno[3,2-b]thiophene, which is readily scaled up to the multi-gram scale. With this synthesis in hand, we initially investigated the properties of poly(thienothiophene-alt-vinylene) polymers incorporating both straight and branched side-chains. Two different polymerization methods were investigated to synthesise the conjugated polymers, namely Stille and Gilch polymerization. The Gilch route was found to lead to high molecular-weight polymers with less cis-defects in the backbone. The polymers were found to be largely amorphous by X-ray diffraction measurements, although there were clear signs of aggregation by optical investigations. Field-effect transistors fabricated with these polymers exhibited charge carrier mobilities up to 0.02 cm2 V-1 s-1 for the straight chain analogue, with the branched polymer displaying lower mobilities. Blends with PC71BM were found to exhibit solar cell device efficiencies up to 2.5 %, with significant differences observed for polymers containing two different side-chains. In the third chapter we investigated the properties of ethynylene-linked 3,6-dialkylthieno[3,2-b]thiophene polymers. The simple homo-polymers were found to exhibit much worse device performance than the analogous vinylene-containing polymers in transistor devices. Co-polymers with a range of electron accepting monomers were also synthesized. These displayed low optical energy gaps and signs of aggregation in the solid state. Transistors were fabricated and their performance examined. In the final part of this thesis, co-polymers bearing 3,6-dialkylthieno[3,2-b]thiophene donor and squaraine acceptor units were synthesized. These zwitterionic conjugated polymers displayed band gaps as low as 1.0 eV. The influence of the nature of the side-chains and co-monomer was investigated with regard to their optoelectronic properties.
40
Pokharel, Sundari D. "Synthesis of Novel Organic Chromophores and Their Characterization." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc699844/.
Full textAbstract:
Nonlinear organic liquids that exhibit two-photon absorption (TPA) function as good optical limiters for sensor protection from laser pulses. L34 (4-butyl-4'-propyl-diphenylethyne) is a liquid organic compound exhibiting nonlinear optical absorption. A thiol- derivatized analog of L34 (“thiol-L34”) was prepared to bind the molecules to the surface of gold nanoparticles. Surface binding is necessary to investigate synergy between nonlinear optical absorption of gold nanoparticles and thiol-L34. Thiol-L34 was prepared in a six-step organic synthesis starting from 3-(4-bromophenyl) propionic acid. Au nanoparticles with <15 nm diameter have been prepared and sensitized with the thiol-L34 compound for assessment of their nonlinear optical behavior. Diazolylmethenes a class of metal-coordinating dyes that are similar to dipyrrins with some substitutions of nitrogen atoms in place of carbon atoms. Modification in the framework of dipyrrinoid dyes via this replacement of nitrogen for carbon atoms may lead to compounds that serve as effective agents for bioimaging and/or photodynamic therapy. Several routes to the synthesis of di-(1,2,3)-triazolylmethenes, di-(1,2,4)-triazolylmethenes, and ditetrazolylmethenes are presented.
41
Goulding, Mark John. "Novel nematic and chiral nematic liquid crystalline materials for use in applications." Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389814.
Full text
42
Carroli, Marco. "Novel materials for direct X-ray detectors based on semiconducting organic polymers." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/9345/.
Full textAbstract:
Conventional inorganic materials for x-ray radiation sensors suffer from several drawbacks, including their inability to cover large curved areas, me- chanical sti ffness, lack of tissue-equivalence and toxicity. Semiconducting organic polymers represent an alternative and have been employed as di- rect photoconversion material in organic diodes. In contrast to inorganic detector materials, polymers allow low-cost and large area fabrication by sol- vent based methods. In addition their processing is compliant with fexible low-temperature substrates. Flexible and large-area detectors are needed for dosimetry in medical radiotherapy and security applications. The objective of my thesis is to achieve optimized organic polymer diodes for fexible, di- rect x-ray detectors. To this end polymer diodes based on two different semi- conducting polymers, polyvinylcarbazole (PVK) and poly(9,9-dioctyluorene) (PFO) have been fabricated. The diodes show state-of-the-art rectifying be- haviour and hole transport mobilities comparable to reference materials. In order to improve the X-ray stopping power, high-Z nanoparticle Bi2O3 or WO3 where added to realize a polymer-nanoparticle composite with opti- mized properities. X-ray detector characterization resulted in sensitivties of up to 14 uC/Gy/cm2 for PVK when diodes were operated in reverse. Addition of nanoparticles could further improve the performance and a maximum sensitivy of 19 uC/Gy/cm2 was obtained for the PFO diodes. Compared to the pure PFO diode this corresponds to a five-fold increase and thus highlights the potentiality of nanoparticles for polymer detector design. In- terestingly the pure polymer diodes showed an order of magnitude increase in sensitivity when operated in forward regime. The increase was attributed to a different detection mechanism based on the modulation of the diodes conductivity.
43
Flora, Ware Howard. "Characterization and optimization of novel materials and interfaces in organic electronic devices." Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/280511.
Full textAbstract:
The research embodied in this text involves the characterization and optimization of novel materials and interfaces critical to the performance of organic electronic devices: Thrust 1. A scheme for elucidating the relative significance of energy vs. charge transfer (ET vs. CT) routes to guest dye emission in organic light-emitting diodes (OLEDs) was developed using near-IR emissive phthalocyanine (Pc) or naphthalocyanine (NPc) dopants. CT processes were observed to occur by an oxidized guest mechanism, which may be predicted from the solution electrochemistry of these materials. Additionally, a new series of quinacridone(QA)-based guest dyes were developed/characterized, modified at the N,N' positions to form four generations of Frechet dendrimers and their t-butyl-terminated analogues. As generation number increases, they exhibited decreased aggregation and increased luminescence efficiencies in the condensed phase. In solution, sharply declining rates of heterogeneous electron transfer were observed. Despite this trend, when these new molecules were doped into OLEDs, ET and CT routes to QA emission were not significantly inhibited. Thrust 2. A series of hybrid metal cluster-organic materials containing between one and seven [Re6(mu3-Se)8] 2+ clusters per molecule were electrochemically characterized. Dimer, trimer, and tetramer assemblies yielded uncoupled cluster oxidations. For cluster 7-mer dendrimers, uncoupled oxidations were observed for unconjugated linking groups, while coupled oxidations were observed with a conjugated linker, suggesting through-bond electrical polarization of the interior cluster. Thrust 3. The first UV-Vis attenuated total reflectance (ATR) method for the simultaneous determination of molecular tilt and azimuthal rotation for ultra-thin films of molecules with circularly-polarized electronic transition dipoles was developed, where a priori assumptions of the mean molecular orientation of either angle are not necessary in order to recover both mean angles. A model Pc-based system was evaluated, where this material is known to form in-plane molecular columns. Assuming a delta distribution in the orientation of each angle, it was determined that the mean tilt of the molecular plane away from the substrate surface is 80 ± 3°, and the mean azimuthal rotation of the molecular plane away from the column direction is 56.9 ± 0.8°. The dependence of molecular orientation on environmental exposure conditions and surface premodifiers was also evaluated.
44
Payne, Maurice Kato. "Development of metal organic materials for use in novel water treatment schemes." Diss., University of Iowa, 2019. https://ir.uiowa.edu/etd/6832.
Full textAbstract:
The ability to construct materials that are specialized for specific tasks is an important challenge for the scientific community. A mature field in this right is that of metal organic materials. These materials are infinitely customizable crystalline materials constructed from metals/metal containing nodes and organic multitopic linkers. Numerous subfields of materials research seek to exploit some of the characteristics and seen-nowhere-else properties of metal organic materials. A nascent, yet promising subfield is the use of metal organic materials in water treatment.
The diminishing access to safe clean water continues to grow as a worldwide problem. Freshwater reserves are decreasing and the human populations who rely on them are increasing. It is a clear need to revolutionize the way the scientific community treats and delivers safe water. Our research group discovered a metal organic material made from hexavalent uranium and the organic ligand iminodiacetate. This material was coined the UMON for its nanotubular shape (uranium metal organic nanotube) and early on it was proven to be unique in the way it allowed water to enter the tube channel and bar any other species from doing the same. I sought to use this material as a vehicle to learn and discover new ways that metal organic materials could be used in the water treatment revolution.
This dissertation will narrate my investigations into specific hypotheses regarding the UMON’s special water properties. Specifically I sought to construct other materials with hexavalent uranium to test whether the presence of uranium was an important factor in a materials discretion for water. I also helped establish new knowledge regarding the UMON itself by discovering its negative thermal expansion and its ability to select for light water (H2O) over heavy water species (D2O, HDO, HTO).
45
Krungleviciute, Vaiva. "Characterization Of Nanoporous Materials Using Gas Adsorption Isotherms: Evaluating Their Potential For Gas Storage And Separation Applications." Available to subscribers only, 2009. http://proquest.umi.com/pqdweb?did=1879014061&sid=7&Fmt=2&clientId=1509&RQT=309&VName=PQD.
Full textAbstract:
Thesis (Ph. D.)--Southern Illinois University Carbondale, 2009."Department of Physics." Keywords: Adsorption, Gas separation, Gas storage, Metal-organic frameworks, Single-walled carbon nanotubes, Nanoporous materials. Includes bibliographical references (p. 86-96). Also available online.
46
Islamoglu, Timur. "SYSTEMATIC POSTSYNTHETIC MODIFICATION OF NANOPOROUS ORGANIC FRAMEWORKS AND THEIR PERFORMANCE EVALUATION FOR SELECTIVE CO2 CAPTURE." VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4264.
Full textAbstract:
Porous organic polymers (POPs) with high physicochemical stability have attracted significant attention from the scientific community as promising platforms for small gas separation adsorbents. Although POPs have amorphous morphology in general, with the help of organic chemistry toolbox, ultrahigh surface area materials can be synthesized. In particular, nitrogen-rich POPs have been studied intensively due to their enhanced framework-CO2 interactions. Postsynthetic modification (PSM) of POPs has been instrumental for incorporating different functional groups into the pores of POPs which would increase the CO2 capture properties. We have shown that functionalizing the surface of POPs with nitro and amine groups increases the CO/N2 and CO2/CH4 selectivity significantly due to selective polarization of CO2 molecule. In addition, controlled postsynthetic nitration of NPOF-1, a nanoporous organic framework constructed by nickel(0)-catalyzed Yamamoto coupling of 1,3,5-tris(4-bromophenyl)benzene, has been performed and is proven to be a promising route to introduce nitro groups and to convert mesopores to micropores without compromising surface area. Reduction of the nitro groups yields aniline-like amine-functionalized NPOF-1-NH2. Adequate basicity of the amine functionalities leads to modest isosteric heats of adsorption for CO2, which allow for high regenerability. The unique combination of high surface area, microporous structure, and amine-functionalized pore walls enables NPOF-1-NH2 to have remarkable CO2 working capacity values for removal from landfill gas and flue gas. Benzimidazole-linked polymers have also been shown to have promising CO2 capture properties. Here, an amine functionalized benzimidazole-linked polymer (BILP-6-NH2) was synthesized via a combination of pre- and postsynthetic modification techniques in two steps. Experimental studies confirm enhanced CO2 uptake in BILP-6-NH2 compared to BILP-6, and DFT calculations were used to understand the interaction modes of CO2 with BILP-6-NH2. Using BILP-6-NH2, higher CO2 uptake and CO2/CH4 selectivity was achieved compared to BILP-6 showing that this material has a very promising working capacity and sorbent selection parameter for landfill gas separation under VSA settings. Additionally, the sorbent evaluation criteria of different classes of organic polymers have been compared in order to reveal structure-property relationships in those materials as solid CO2 adsorbents.
47
Little, Mark Simon. "The synthesis of novel polycyclic aromatic hydrocarbons : the search for organic semiconductor materials." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/the-synthesis-of-novel-polycyclic-aromatic-hydrocarbons-the-search-for-organic-semiconductor-materials(e81cb21c-e801-449d-9bbf-4ad02659d30a).html.
Full textAbstract:
A collection of 4,10-chrysene derivatives was prepared via the BHQ (Bull-Hutchings- Quayle) reaction, their electronic and morphological properties analysed and assessed for suitability as organic semiconductor (OSC) materials. Larger polycyclic aromatic hydrocarbons (PAHs) such as benzo[k]tetraphenes and dinaphtho[1,2,-b:1',2'- k]chrysenes were then prepared and similarly characterised. An acene-based OSC material TMTES-pentacene was also prepared. It is proposed that non-linear PAH- based OSC materials may provide an alternative to popular acene-based materials; offering advantages in stability, diversity and handling.
48
White, Brittany. "The Synthesis of Functionalized Cycloparaphenylenes as Novel Biocompatible Fluorescent Probes and Organic Materials." Thesis, University of Oregon, 2019. http://hdl.handle.net/1794/24521.
Full textAbstract:
Conjugated macrocycles have emerged as novel structural motifs that modulate the electronic properties of organic molecules because of their strained and contorted structures. Cycloparaphenylenes, known as nanohoops, are a particularly attractive scaffold for the design of new types of carbon nanomaterials because of their size-selective synthesis, radially oriented π-systems and tunable electronic properties. The development of modular syntheses of nanohoops over the past decade should enable the preparation of substituted derivatives that can be tuned for applications in biology and materials science.
Chapter I provides a brief overview of conjugated macrocycles recently reported in the literature with a discussion of the structural effects that are responsible for the remarkable properties of this class of molecules. Chapter II highlights a scalable and mild synthetic approach developed in our lab to prepare nanohoop conjugated macrocycles and expands the generality of this methodology with the formal synthesis of natural product Acerogenin E. Chapter III describes the synthesis of cycloparaphenylenes with versatile functional handles and uncovers the reactivity of the strain nanohoop backbone under reaction conditions that promote the formation of radical cations. Chapter IV takes advantage of the functional groups described in chapter III to develop the first example of nanohoops as a new class of biocompatible fluorophores. Chapter V details a novel synthetic approach that enables the incorporation of the linear acene pentacene into the nanohoop backbone and reports our findings on the impact that the macrocyclic structure has on the properties of this organic semiconductor. In summary, the findings discussed in this dissertation provide synthetic strategies for the selective functionalization of nanohoops and highlight this class of molecules as a novel scaffold for the design of new types of carbon nanomaterials.
This dissertation includes previously published and unpublished co-authored material.
49
Sanderyd, Viktor. "Novel Hybrid Nanomaterials : Combining Mesoporous Magnesium Carbonate with Metal-Organic Frameworks." Thesis, Uppsala universitet, Nanoteknologi och funktionella material, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-355366.
Full textAbstract:
Nanotechnology as a field has the potential to answer some of the major challenges that mankind faces in regards to environmental sustainability, energy generation and health care. Though, solutions to these concerns can not necessarily rely on our current knowhow. Instead, it is reasonable to expect that humanity must adapt and learn to develop new materials and methods to overcome the adversities that we are facing. This master thesis has involved developing novel materials, serving as a small step in the continuous march towards a bright future where this is possible. More specifically, this work sought to combine mesoporous magnesium carbonate with various metal-organic frameworks to utilize the beneficial aspects from each of these constituents. The ambition was that these could be joined to render combined micro-/mesoporous core-shell structures, with high surface areas and many active sites whilst maintaining a good permeability. Numerous different synthesis routes were developed and explored in the pursuit of viable routes to design novel materials with potential future applications within for instance drug delivery, water harvesting from air and gas adsorption. Coreshell structures of the hydrophilic mesoporous magnesium carbonate covered with the hydrophobic zeolitic imidazole framework ZIF-8 was successfully synthesized for the first time, and practical studies demonstrated a dramatically enhanced water stability, which is perceived to have an impact on further research on these materials. ZIF-67 was also combined with mesoporous magnesium carbonate in a similar manner. Further, Mg-MOF-74 was grown directly from mesoporous magnesium carbonate, where the latter acted as a partially self-sacrificing template, with the aim of rendering a porous hierarchical structure with contributions from the micro- and mesoporous ranges. The outcomes of all these syntheses were characterized using several analyzing methods such as scanning electron microscopy, X-ray diffraction, energy dispersive spectroscopy and nitrogen sorption analysis.
50
Haja, Mohideen Mohamed Infas. "Novel metal organic frameworks : synthesis, characterisation and functions." Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/1892.
Full textAbstract:
The synthesis and properties of novel Metal Organic Frameworks were investigated and reported in this thesis. Thirteen new materials have been synthesized and their properties have been discussed with nine of the structures being solved. The most interesting and useful MOF among the thirteen materials is STAM-1, a copper-based Metal Organic Framework in which the starting linker (Benzene-1,3,5-tricarboxylic acid) undergoes selective in situ monoesterification during the synthesis. The monoesterified BTC can be recovered easily from the MOF, opening up MOF synthesis as a “protection” tool for unexpected selectivity in preparative chemistry that is difficult to accomplish using standard organic chemistry approaches. The selective linker derivatisation leads to the formation of a porous MOF with two types of accessible channel; one hydrophilic lined by copper and the other hydrophobic, lined by the ester groups. The unique structure of the pores leads to unprecedented adsorption behaviour, which reacts differently to gases or vapours of dissimilar chemistry and allows them to access different parts of the structure. The structural flexibility of STAM-1 shows significant differences in the kinetics of O₂ and N₂ adsorption, showing potential for new materials to be developed for air separation. Having two types of channel systems, adsorption can be switched between the two channels by judicious choice of the conditions; a thermal trigger to open the hydrophilic channel and a chemical trigger to open the hydrophobic channel. The storage and release capability of NO in STAM-1 was investigated for use in biomedical applications. Successful studies showed the strength of the antibacterial effects of NO loaded STAM-1, by using three different bacterial strains as a test of performance and were found to be bactericidal. Furthermore the antibacterial effects of NO free STAM-1 were also probed and found to be bactericidal even with low concentrations of the material such as 5 wt%. STAM-1 showed some complex magnetic behaviour by displaying strong antiferromagnetic properties at room temperature and ferromagnetic properties at lower temperatures. The antiferromagnetic coupling was observed within the dimer and ferromagnetic coupling between the dimers. This property of ferromagnetism can only be attributed to the corporation of magnetic dimers in the framework. STAM-2 displays a different magnetic behaviour than STAM-1 which shows paramagnetic properties at room temperature and antiferromagnetic properties at lower temperatures. Other novel MOFs were also successfully characterised and their properties were investigated for potential applications.