Dissertations / Theses on the topic 'Fluorocarbons'
To see the other types of publications on this topic, follow the link: Fluorocarbons.
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 'Fluorocarbons.'
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
Niyogi, Sandip. "Synthesis and characterization of molecules to study the conformational barriers of fluorocarbon chains." Thesis, University of North Texas, 2000. https://digital.library.unt.edu/ark:/67531/metadc2511/.
Full textAbstract:
Fluorocarbons are known to be stiffer than their hydrocarbon analogues, a property that underlines the extensive industrial application of fluorocarbon materials. Although there has been previous studies on the rotational barrier of molecules having fluorocarbon centers, a detailed systematic study is necessary to quantify flurocarbon stiffness. The molecules, Pyrene-(CF2)n-Pyrene, Pyrene-(CF2)n-F, Pyrene-(CH2)n-Pyrene and Pyrene-(CH2)n-H were therefore synthesized to enable the determination of the barrier to rotation of the carbon backbone in fluorocarbons. Conformational studies will be completed with steady-state and time-dependent emission spectroscopy.
2
Ma, Ruowei. "Quantification and partition of perfluorochemicals in Hong Kong wastewater sludge." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B43223862.
Full text
3
Lindup, Richard J. "Metal-mediated borylation of fluorocarbons." Thesis, University of York, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434017.
Full text
4
Tang, Yi. "Atmospheric fate of various fluorocarbons." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/10598.
Full text
5
Wang, Fei, and 王飞. "Behavior of perfluorochemicals on solid surfaces: sorption and mineralization processes." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B50899892.
Full textAbstract:
The study evaluated the sorption behavior of PFOS and PFOA on γ-alumina and boehmite. The results of adsorption kinetics on γ-alumina and boehmite show that it takes 48 h to reach equilibrium. The adsorption isotherms reveal the maximum adsorption capacities of PFOS and PFOA are different due to their different functional groups. An increase in pH leads to a decrease in PFOS and PFOA adsorption on alumina, which may be attributed to the reduction in electrostatic interaction. The adsorption of both PFOS and PFOA decreases with an increase in ionic strength due to the compression of the electrical double layer. The different sorption level of PFC on γ-alumina and boehmite indicated that the crystal phase of mineral also affected the sorption process. The sorption of PFOS and PFBuS on boehmite was significantly retarded by the competitive sorption of humic acid (HA), implying that PFOS and PFBuS are likely more mobile in water and groundwater systems enriched with HA. The sorption behavior of PFOS and PFBuS on the HA-modified boehmite surface was also found to differ due to their different chain lengths. In addition, the results revealed that the sorption of PFOS and PFBuS on HA-modified boehmite is pH-dependent.
The isotherm study of FOSA on three types of microplastics indicated that hydrophobic interaction plays a dominant role in the sorption process and the molecule structure of different microplastics can affect its sorption level. The PFOS sorption isotherm indicated that electrostatic interaction plays an important role in the PFOS sorption process on PE and PS while its sorption on PVC was electrostatic interaction independent. The effects of pH and ionic strength indicated that electrostatic interaction plays an important role in PFOS sorption process. The kinetic study showed that the PCMAs had a rapid sorption towards PFAS species and the isotherm study indicated that hydrophobic interaction played an important role in the sorption process. The sorption of PFOS by the PCMAs was not significantly affected by the pH and slightly decreased with an increase in ionic strength. Moreover, the sorbent had showed excellent regeneration performance.
Two main fluorine mineralization mechanisms leading to the substantial formation of CaF2 and Ca5(PO4)3F phases were observed. They had a close relationship with the thermal treatment condition and the PFOS content of the sludge. At low temperatures (300C -600C), CaF2 dominated in the product and increases in treatment time and temperature generally enhanced the fluorine transformation. However, at higher temperatures (700C -900C), increases in treatment time and temperature had a negative effect on the overall efficiency of the fluorine crystallization. The results suggest that in the high temperature environment there were greater losses of gaseous products such as HF and SiF4 in the transformation of CaF2 to Ca5(PO4)3F, the hydrolysis of CaF2, and the reaction with SiO2. The quantitative analysis also showed that when treating sludge with low PFOS content at high temperatures, the formation of Ca5(PO4)3F may be the primary mechanism for the mineralization of the fluorine in PFOS.published_or_final_version
Civil Engineering
Doctoral
Doctor of Philosophy
6
Jones, S. L. "Functional fluorocarbons via free radical additions to hexafluoropropene." Thesis, Durham University, 1987. http://etheses.dur.ac.uk/6781/.
Full textAbstract:
The effect of substituents on the carbon-hydrogen bond reactivity in free radical additions to hexaf1uoropropene has been investegated. Ethers, amines, amides, isocyanates and silanes all give Free radical adducts. The order of reactivity has been compiled. The reactivity of cyclic ethers, amines and amides is discussed in terms of the stereoelectronic effect. The reactivity of tetrahydrofuran and N-methylpyrrolidine towards hexaf1uoropropene under uninitiated conditions has also been demonstrated. The ease of hydrogen abstraction from the substrates was estimated using a method based on the thermal decomposition of ditertiarybutylperoxide. A correlation between the ease of hydrogen abstraction and free radical reactivity is demonstrated, although the reactivity of aldehydes is not simply explained. The adducts of ethers and amines can be dehydrofluorinated to give a variety of alkenes. Further reactions of aldehyde and isocyanate adducts has given good synthetic routes to other functionally substituted fluorocarbons. The amide adducts are also a useful source o-f fluorinated amines which cannot be obtained directly. An amine 1:1 adduct has been fully fluorinated over cobalt trifluoride at 440 C in good yield, although higher adducts give lower yields. Remarkably high yields of perfluorinated alkanes are produced by successive reaction with sulphur tetrafluoride and cobalt trifluoride.
7
Chatterjee, Ritwik 1974. "Evaluation of unsaturated fluorocarbons for dielectric Etch applications." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/86859.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2003.Includes bibliographical references (p. 175-183).
The semiconductor industry is currently faced with the problem of the use and emissions of strong global warming compounds, known as perfluorocompounds (PFCs) for dielectric etch applications. The release of global warming compounds from this and other sources is suspected to result in changes in the earth's climate and weather patterns. Quantitative targets for emissions reduction set by the World Semiconductor Council (WSC) makes it urgent to find a solution to this issue. A long-term means of approaching this problem is to find and develop alternative chemistries that are more environmentally benign without sacrificing performance. Several classes of chemistries have been investigated to date, including hydrofluorocarbons (HFCs), iodofluorocarbons (IFCs), and NF3/hydrocarbons. One class of chemistries that have shown considerable promise is the unsaturated fluorocarbons (UFCs). The research documented herein uses the UFCs to assess etch process and emissions performance. Not only are these novel chemistries tested on conventional silicon dioxide films, but also on new low-k dielectrics that are likely candidates for future generation process flows. Emissions and process performance are reported for each of the different gases. The prospects for integration of some of these chemistries to next generation processes are good from both a process and emissions standpoint. The UFCs are not strong greenhouse gases as a result of their short atmospheric lifetimes (typically less than a day). Unlike many of the previous alternative chemistries studied, the emissions from UFCs are due to reformation of reactive products into strong global warming gases, specifically PFCs and HFCs, in the plasma environment. In this work, the formation of plasma effluents has been studied.
(cont.) In this work, the formation of plasma effluents has been studied. These reformation products are not only a result of the reformation of reactive species from the breakup of the feed gas, but also a result of the interaction of the plasma with surfaces in the etch chamber, including the wafer being etched. Process performance has been assessed by performing cross-sectional scanning electron microscopy (SEM). Emissions data have been collected using Fourier transform infrared spectroscopy (FTIR). In-situ process monitoring methods such as optical emission spectroscopy (OES) and residual gas analysis (RGA) have been used in some experiments. Ex-situ studies of fluorocarbon deposited films have been performed using X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (TOF-SIMS). Screening experiments performed on an Applied Materials HDP high-density etch chamber showed that all of the UFCs in addition to a fluorinated ether were capable of process performance comparable to PFC based processes, such as C3F8. These studies showed that octafluorocyclopentene and hexafluoropropene processes result in greater than 70% emissions reduction compared to a C3F8-based reference process. Three isomers of C4F6 performed even better, with greater than 80% emissions reduction. Hexafluorobenzene based processes displayed the greatest silicon dioxide etch emissions reduction of 97% ...
by Ritwik Chatterjee.
Ph.D.
8
Jackson, Philip R. "Thermodynamic studies of binary mixtures involving aromatic fluorocarbons." Thesis, University of Leicester, 1986. http://hdl.handle.net/2381/33750.
Full textAbstract:
Solid-liquid phase diagrams have been determined for binary systems of hexafluorobenzene + naphthalene-type compounds, and indicate strong 1:1 congruently melting point complexes. Hexafluorobenzene + cis- and + trans-deca1in were found to give simple eutectic phase diagrams. Excess enthalpies, excess volumes and excess Gibbs functions have been measured for the same hexaf1uorobenzene + naphthalene-type compound mixtures and are large and negative, which is characteristic of systems where specific interactions take place. This contrasts with the large positive excess functions found with hexafluorobenzene + decalin systems, where only dispersion forces are assumed present. The excess Gibbs function for hexafluorobenzene + trans- and cis-decalin have been determined theoretically from freezing point data as well as directly from vapour pressure measurements. A batch calorimeter, besides being used for excess enthalpy measurememts, has been employed in determining heats of solution, which lead to a value for the enthalpy change for the process, solid + solid ? complex. The possibility of charge-transfer interactions occuring in hexafluorobenzene + naphthalene-type compound systems has been discussed in terms of HOMO/LUMO overlap considerations and is supported by the observation that pentafluorocyanobenzene forms stronger (higher melting point) complexes with 1- and 2-methylnaphthalene, than hexafluorobenzene does.
9
Gilliam, Mary A. "A plasma polymerization investigation and low temperature cascade arc plasma for polymeric surface modification." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4355.
Full textAbstract:
Thesis (Ph.D.)--University of Missouri-Columbia, 2006.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (April 25, 2007) Vita. Includes bibliographical references.
10
Ma, Ruowei, and 馬若為. "Quantification and partition of perfluorochemicals in Hong Kong wastewater sludge." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43223862.
Full text
11
Ntwampe, Seteno Karabo Obed. "A perfluorocarbon-based oxygen delivery system to a membrane bioreactor." Thesis, [S.l. : s.n.], 2009. http://dk.cput.ac.za/cgi/viewcontent.cgi?article=1059&context=td_cput.
Full text
12
Poter, Simon Christopher. "Fluid phase coexistence by molecular simulation." Thesis, University of Southampton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242790.
Full text
13
Hunter, Nicole Marie. "High-Valent Perfluoronickelacycles: Intermediates for “Green” Routes to Fluorocarbons and Their Derivatives." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20030.
Full textAbstract:
Fluorocarbons (FCs) and their derivatives (FCDs) are heavily relied on due to their wide range of uses (e.g. solvents, surfactants, refrigerants, and pharmaceuticals). Currently, FCs and FCDs are produced on an industrial scale via energy-intensive processes, using hazardous materials. Hence, new catalytic chemical technologies are required to provide cleaner and greener synthetic routes to partially fluorinated materials. The exploration of fundamental organofluorometallic chemistry of base metals, such as nickel, has potential to advance the development of novel catalytic processes towards this end. It has been established previously that zero-valent nickel complexes have the ability to efficiently catalyze the hydrodimerization of polyfluoroalkenes. The reactivity of the intermediate polyfluoronickelacycles was found to be influenced by modifications in the ligand sphere. Furthermore, an increase in oxidation state of the central metal atom was proposed as an additional strategy to increase the reactivity of the M-RF bond. In this thesis, through variation of the ligand environment and oxidation state of nickel, we have further developed the chemistry of high-valent polyfluoronickelacycles. Synthesis and characterization (NMR, EPR, UV/Vis, IR spectroscopy and electrochemistry) of new trivalent polyfluoronickelacycles are described as well as attempts to generate the corresponding tetravalent cations. Attempts to induce nucleophilic insertion of acetonitrile into the Ni-RF bond were also investigated herein. Challenges were encountered with the isolation of the tetravalent cations due to decomposition to the corresponding divalent nickelacycle.
14
Lam, Po Man. "Fluorocarbon coatings on indium tin oxide surface for organic light-emitting diodes." access abstract and table of contents access full-text, 2004. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b2117443xa.pdf.
Full textAbstract:
Thesis (M.Sc.)--City University of Hong Kong, 2004.At head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Sept. 1, 2006) Includes bibliographical references.
15
Calvosa, Frank. "Supercritical fluid extraction of polybrominated diphenyl ethers (PBDEs) from standard reference material 2585 (organic contaminants in house dust) with 1,1,1,2-tetrafluoroethane (R134a)." Click here for download, 2008. http://proquest.umi.com/pqdweb?did=1490081841&sid=1&Fmt=2&clientId=3260&RQT=309&VName=PQD.
Full text
16
Palihawadana, Prasanga D. Ariyasinghe Wickramasinghe M. "Total electron scattering cross sections of Tetrafluoromethane, Trifluoromethane, Hexafluoroethane, and Octafluorocyclobutane in the energy range 0.10 to 4.50 keV." Waco, Tex. : Baylor University, 2008. http://hdl.handle.net/2104/5287.
Full text
17
Lindsay, Clifford Fry. "The Measurement of Decomposition Products of Select Gases as an Indicator of a Concealed Mine Fire." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/51091.
Full textAbstract:
Currently, techniques used to determine whether or not there is a concealed fire in an inaccessible area of a coal mine are not definitive. Inaccessible areas of coal mines include:
1. A mined-out area, such as a long-wall gob.
2. A mine area, or entire mine, that has been sealed to extinguish a fire.
3. The interior of pillars in a mine.
4. Abandoned mines.
Mined-out areas — gobs — are particularly problematic. The standard practice is to obtain measurements for certain gas concentrations from an inaccessible area, and to apply certain rules to the obtained concentrations in order to try to decipher whether or not there is a fire in the area. Unfortunately, none of the gas measurements, and the associated rules that are applied, are free of potential problems. Therefore, there is always some degree of uncertainty in any decision that is based on the current methods.
A more definitive method of determining whether or not a concealed fire exists would be valuable; perhaps avoiding unnecessary exposure of miners to risks, and unnecessary exposure of mining companies to economic loss. This study details the inadequacies of the current methods for determining the presence of a fire in an inaccessible area of a coal mine, and proposes two novel methods for overcoming the current inadequacies.
The first method that was studied involves looking for the presence of the radioisotope carbon-fourteen in the carbon monoxide in the return airways of coal mines. For the vast majority of coal mines, if there is no fire anywhere in the coal mine, carbon monoxide should not have any carbon-fourteen in it. If there is a fire, the carbon monoxide should have carbon-fourteen in it. This method is based on the Boudouard Reaction, which documents a reaction between carbon, carbon monoxide, and carbon dioxide that only occurs at temperatures that only occur with a fire. Because of the very small amounts of carbon-fourteen in carbon dioxide in the atmosphere, and the small amount of carbon monoxide usually present in a coal mine atmosphere, there does not appear to be any way, currently, to implement this method. Instrumentation that may allow implementation of this method, in the future, is discussed.
The second method, that was studied, involves introducing a select, gaseous, organic compound into an inaccessible area; and then using a gas chromatograph to test for the presence of definitive fire decomposition products of the initial organic compound in the atmosphere that is exiting the inaccessible area.
Laboratory tests, conducted as part of this study, established the concept of this novel method of using select, organic compounds for definitively determining whether or not a concealed fire exists in an inaccessible part of a coal mine. Based on an initial screening of 5 different compounds, two compounds have been selected for use as 'fire indicator gases' with the acronym of 'FIGs.' These two compounds are:
1. C6-Perfluoroketone (CF3CF2C(=O)CF(CF3)2 )
2. 1,1 Difluoroethane (CH3CHF2)
This study provides suggestions as to how to look for other potential FIGs, and how to improve the testing of potential FIGs.
Examples of all four of the types of inaccessible areas listed above are discussed, particularly from the viewpoint of how FIGs could be utilized in each case, and how FIGs could provide better information in each case.
In addition, as a by-product of the experiments conducted for this work, this study identifies at least six gases that might be used simultaneously as tracer gases for complex ventilation studies in a mine, or elsewhere.Ph. D.
18
Goh, Fernie. "The use of perfluorocarbons in encapsulated cell systems: their effect on cell viability and function and their use in noninvasively monitoring the cellular microenvironment." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39560.
Full textAbstract:
Implantation of tissue engineered pancreatic constructs can provide for a physiologic regulation of blood glucose levels. A major concern in designing such constructs is ensuring sufficient oxygenation of the cells, as oxygen is usually the limiting nutrient affecting cell viability and function. Furthermore, in vivo factors influencing construct oxygenation often lead to implant failure, and are detected primarily on end physiologic effects. The ability of perfluorocarbons (PFCs) to dissolve large amounts of oxygen and their high fluorine content makes these compounds a potentially valuable oxygen delivery tool and good 19F Nuclear Magnetic Resonance (NMR) markers for dissolved oxygen concentration (DO). Experimental studies and simulations showed that although the addition of 10 vol% PFC increased construct oxygenation, this improvement was minimal and had limited benefits on the growth and function of encapsulated bTC-tet cells under normoxic and hypoxic conditions. A dual PFC method that utilizes 19F NMR spectroscopy was developed to noninvasively monitor DO within a tissue construct and in its surroundings. In vitro studies using an NMR-compatible bioreactor demonstrated the feasibility of this method to monitor the DO within alginate beads containing metabolically active bTC-tet cells, relative to the DO in the culture medium, under perfusion and static conditions. In vivo, the method was capable of acquiring real-time DO measurements in murine models. Measured DO can be correlated with the physiological state of the implant examined post-explantation and was compatible with the therapeutic function of the implant.
19
Nell, Annalien. "Study of the plasma based production of tetrafluoroethylene." Thesis, Stellenbosch : Stellenbosch University, 1999. http://hdl.handle.net/10019.1/51440.
Full textAbstract:
Thesis (MIng) --Stellenbosch University, 1999.ENGLISH ABSTRACT: A method was developed at the Atomic Energy Corporation of South Africa (AEC) for the plasma based production of tetrafluoroethylene (TFE). The process involves the feeding of carbon particles into a direct-current CF4 plasma. The resultant plasma gas is quenched rapidly to obtain TFE and other fluorocarbons. The mixing of the particles with the plasma gas is very important in order to achieve a high C:F-ratio in the gas phase, which promotes the desired reactions. The gas enthalpy in the reactor is a governing factor in the TFE yields that are obtained. In this study research was done on particle mixing and the enthalpy distribution in the laboratory scale reactor. An enthalpy probe was used as the main diagnostic tool. Results indicated that particle mixing is quite uniform throughout the reactor. A basic one-dimensional mechanistic model of the reactor was also expanded to assist in· the scale-up of the process. In its present form the model is adequate for predicting trends in the reactor. The model could still be expanded further to include reaction kinetics and internal heat transfer in the particles. Considering the restrictions of the model, satisfactory agreement was obtained between the model and experimental results.
AFRIKAANSE OPSOMMING: 'n Proses vir die plasmagebaseerde produksie van tetrafluoroetileen (TFE) is deur die Atoomenergiekorporasie van Suid-Afrika (AEK) ontwikkel. Koolstofpartikels word in 'n gelykstroomCF4- plasma gevoer en die resulterende plasmagas word vinnig geblus ten einde TFE en ander fluoor-koolstofverbindings as produkte te verkry. Goeie vermenging van die koolstofpartikels met die plasmagas is van uiterste belang ten einde 'n hoe C:F-verhouding, wat die gewenste reaksies bevorder, in die gasfase te verkry. Die entalpie van die plasmagas in die reaktor is 'n bepalende faktor in die opbrengs TFE wat verkry word. Vir die doel van hierdie werkstuk is navorsing op laboratoriumskaal gedoen oor partikelvermenging en die entalpie-verspreiding in die reaktor. Die hoof diagnostiese apparaat wat vir die doel aangewend is, is die entalpiesonde. Resultate toon dat partikelvermenging naastenby uniform deur die reaktor voorkom. Verder is 'n basiese een-dimensionele meganistiese model van die reaktor uitgebrei ten einde van nut te wees in die opskaling van die proses. In sy huidige vorm is die model voldoende om algemene neigings in die reaktor te voorspel. Die model kan nog verder uitgebrei word om reaksie-kinetika en interne hitte-oordrag in die partikels in te sluit. Die beperkings van die model in ag genome, is ooreenstemming tussen die model en eksperimentele resultate egter bevredigend.
20
Copin, Elodie. "Novel fluorocarbon iodides." Thesis, Durham University, 2002. http://etheses.dur.ac.uk/4174/.
Full textAbstract:
This work describes the three-step synthesis of some new fluorocarbon iodides. First, functionalisations of carbon-hydrogen bonds, using fluorinated alkenes via a free radical chain mechanism, were carried out. The HFP-adducts were then further functionalised by elimination of hydrogen fluoride to yield a series of fluoroalkenes, which were then converted to fluorocarbon iodides by means of a mixture of IF(_5)/I(_2) (corresponding to iodine monofluoride formed in situ). Chemistry of the new fluorocarbon iodides was investigated, especially in reactions with thiols.
21
Veverková, Radka. "Plazmochemická depozice tenkých fluorocarbonových vrstev." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2011. http://www.nusl.cz/ntk/nusl-216697.
Full textAbstract:
Deposition of thin films is one of the most widespread applications used for the changes of surface properties of various materials. This diploma thesis is focused on diagnosing of thin film generated by a PECVD technique. The capacitively coupled RF discharge at low pressure was used for the thin films deposition using tetrafluoromethane (CF4) with addition of hydrogen (H2) as a precursor. The aim of the work was the search of optimal conditions for a hydrophobic thin layer preparation on the surface of polymer NOA. The depositions were performed in continuous and pulsed mode with different duty cycle. The discharge was monitored using optical emission spectroscopy and in situ mass spectrometry. Thin films structure and properties were characterized using water contact angle measurements, X-ray photoelectron spectroscopy, infrared spectroscopy and optical ellipsometry. The influence of varying power, gas mixture composition and discharge mode were investigated. Water contact angle was the highest for a deposition in a continuous mode. Decomposition processes inside the reactor were observed by using mass spectrometry and optical emission spektrokopie. X-ray photoelectron spectroscopy provided information about the chemical bonds represented on the surface of sample. These were mainly C – C/C – H, C – O, O = C - O groups for sample without layer. Other chemical bonds were observed after the deposition. These were mainly C – CF, CF2 and CF3 groups. The film thickness of about 8,2 nanometers was measured by optical ellipsometry. The obtained results may be used as a fundament for further more advanced study of plasma chemically prepared thin fluorocarbon films and their properties.
22
Esteoulle, Lucie. "Développement de conjugués peptidiques fluorocarbonés pour augmenter la stabilité plasmatique de peptides visant des récepteurs couplés aux protéines G." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAF058.
Full textAbstract:
Afin d’améliorer la stabilité plasmatique de peptides, nous avons développé une nouvelle stratégie basée sur l’introduction d’une chaîne fluorocarbonée dans la séquence d’un peptide natif. En appliquant le concept à l’apeline-17, un peptide présentant un intérêt potentiel pour le traitement de maladies cardiovasculaires, nous avons amélioré sa stabilité plasmatique de 4 min à plus de 24 h ainsi que son efficacité in vivo. L’étude du mécanisme de stabilisation a permis de mettre en évidence la liaison de la fluoroapeline à l’albumine, conduisant à la protection du peptide vis-à-vis de la protéolyse. Le concept a été appliqué à d’autres peptides tels que l’apeline-13, l’angiotensine II, l’ocytocine et la spexine, démontrant ainsi l’étendue et les limitations de la méthode. Enfin, nous avons également conçu des sondes fluorescentes « turn-on » originales capables de révéler leur fluorescence uniquement après liaison au récepteur ciblé. Ces sondes pourront nous servir, par la suite, pour l’étude in vivo de la biodistribution des fluoropeptidesIn order to improve the plasma stability of peptides, we have developed a new strategy based on the introduction of a fluorocarbon chain in the sequence of a native peptide. By applying this concept to apelin-17, a peptide showing a potential interest for the treatment of cardiovascular diseases, we have improved its plasma stability from 4.6 min to more than 24 h as well as its in vivo efficacy. The mechanism leading to the increase of plasma stability has been carefully investigated demonstrating the binding of the fluoroapeline to the albumin, leading to protection towards roteolysis. The concept has been applied to other peptides such as apelin-13, angiotensin II, oxytocin and spexine, showing the extension and the limitations of this method. Finally, we have designed original fluorescent fluorogenic probes which turn on their fluorescence only after binding to the targeted receptor. These probes could be used for in vivo biodistribution studies of fluoropeptides
23
Cochin, D., P. Hendlinger, and André Laschewsky. "Polysoaps with fluorocarbon hydrophobic chains." Universität Potsdam, 1995. http://opus.kobv.de/ubp/volltexte/2008/1734/.
Full textAbstract:
A series of amphiphilic copolymers is prepared by copolymerization of choline methacrylate with 1,1,2,2-tetrahydroperfluorooctyl methacrylate in varying amounts. The copolymers bearing fluorocarbon chains are studied concerning their effects on viscosity, solubilization and surface activity in aqueous solution, exhibiting a general behavior characteristic for polysoaps. The results are compared with the ones obtained for an analogous series of amphiphilic copolymers bearing hydrocarbon chains.
24
Schuster, Paul Xaver. "Biotransformation of trans-1,1,1,3-tetrafluoropropene, 2,3,3,3-tetrafluoropropene and 1,2,3,3,3-pentafluoropropene." kostenfrei, 2009. http://nbn-resolving.de/urn/resolver.pl?urn=nbn:de:bvb:20-opus-43716.
Full text
25
Haworth, Naomi Louise. "Quantum Chemical Studies of Thermochemistry, Kinetics and Molecular Structure." Thesis, The University of Sydney, 2003. http://hdl.handle.net/2123/509.
Full textAbstract:
This thesis is concerned with a range of chemical problems which are amenable to theoretical investigation via the application of current methods of computational quantum chemistry. These problems include the calculation of accurate thermochemical data, the prediction of reaction kinetics, the study of molecular potential energy surfaces, and the investigation of molecular structures and binding. The heats of formation (from both atomisation energies and isodesmic schemes) of a set of approximately 120 C1 and C2 fluorocarbons and oxidised fluorocarbons (along with C3F6 and CF3CHFCF2) were calculated with the Gaussian-3 (G3) method (along with several approximations thereto). These molecules are of importance in the flame chemistry of 2-H-heptafluoropropane, which has been proposed as a potential fire retardant with which to replace chloro- and bromofluorocarbons (CFC�s and BFC�s). The calculation of the data reported here was carried out in parallel with the modelling studies of Hynes et al.1-3 of shock tube experiments on CF3CHFCF3 and on C3F6 with either hydrogen or oxygen atoms. G3 calculations were also employed in conjunction with the experimental work of Owens et al.4 to describe the pyrolysis of CFClBr2 (giving CFCl) at a radiation wavelength of 265 nm. The theoretical prediction of the dissociation energy of the two C-Br bonds was found to be consistent with the energy at which carbene production was first observed, thus supporting the hypothesis that the pyrolysis releases two bromine radicals (rather than a Br2 molecule). On the basis of this interpretation of the experiments, the heat of formation of CFClBr2 is predicted to be 184 � 5 kJ mol-1, in good agreement with the G3 value of 188 � 5 kJ mol-1. Accurate thermochemical data was computed for 18 small phosphorus containing molecules (P2, P4, PH, PH2, PH3, P2H2, P2H4, PO, PO2, PO3, P2O, P2O2, HPO, HPOH, H2POH, H3PO, HOPO and HOPO2), most of which are important in the reaction model introduced by Twarowski5 for the combustion of H2 and O2 in the presence of phosphine. Twarowski reported that the H + OH recombination reaction is catalysed by the combustion products of PH3 and proposed two catalytic cycles, involving PO2, HOPO and HOPO2, to explain this observation. Using our thermochemical data we computed the rate coefficients of the most important reactions in these cycles (using transition state and RRKM theories) and confirmed that at 2000K both cycles have comparable rates and are significantly faster than the uncatalysed H + OH recombination. The heats of formation used in this work on phosphorus compounds were calculated using the G2, G3, G3X and G3X2 methods along with the far more extensive CCSD(T)/CBS type scheme. The latter is based on the evaluation of coupled cluster energies using the correlation consistent triple-, quadruple- and pentuple-zeta basis sets and extrapolation to the complete basis set (CBS) limit along with core-valence correlation corrections (with counterpoise corrections for phosphorus atoms), scalar relativistic corrections and spin-orbit coupling effects. The CCSD(T)/CBS results are consistent with the available experimental data and therefore constitute a convenient set of benchmark values with which to compare the more approximate Gaussian-n results. The G2 and G3 methods were found to be of comparable accuracy, however both schemes consistently underestimated the benchmark atomisation energies. The performance of G3X is significantly better, having a mean absolute deviation (MAD) from the CBS results of 1.8 kcal mol-1, although the predicted atomisation energies are still consistently too low. G3X2 (including counterpoise corrections to the core-valence correlation energy for phosphorus) was found to give a slight improvement over G3X, resulting in a MAD of 1.5 kcal mol-1. Several molecules were also identified for which the approximations underlying the Gaussian-n methodologies appear to be unreliable; these include molecules with multiple or strained P-P bonds. The potential energy surface of the NNH + O system was investigated using density functional theory (B3LYP/6-31G(2df,p)) with the aim of determining the importance of this route in the production of NO in combustion reactions. In addition to the standard reaction channels, namely decomposition into NO + NH, N2 + OH and H + N2O via the ONNH intermediate, several new reaction pathways were also investigated. These include the direct abstraction of H by O and three product channels via the intermediate ONHN, giving N2 + OH, H + N2O and HNO + N. For each of the species corresponding to stationary points on the B3LYP surface, valence correlated CCSD(T) calculations were performed with the aug-cc-pVxZ (x = Q, 5) basis sets and the results extrapolated to the complete basis set limit. Core-valence correlation corrections, scalar relativistic corrections and spin orbit effects were also included in the resulting energetics and the subsequent calculation of thermochemical data. Heats of formation were also calculated using the G3X method. Variational transition state theory was used to determine the critical points for the barrierless reactions and the resulting B3LYP energetics were scaled to be compatible with the G3X and CCSD(T)/CBS values. As the results of modelling studies are critically dependent on the heat of formation of NNH, more extensive CCSD(T)/CBS calculations were performed for this molecule, predicting the heat of formation to be 60.6 � 0.5 kcal mol-1. Rate coefficients for the overall reaction processes were obtained by the application of multi-well RRKM theory. The thermochemical and kinetic results thus obtained were subsequently used in conjunction with the GRIMech 3.0 reaction data set in modelling studies of combustion systems, including methane / air and CO / H2 / air mixtures in completely stirred reactors. This study revealed that, contrary to common belief, the NNH + O channel is a relatively minor route for the production of NO. The structure of the inhibitor Nd-(N'-Sulfodiaminophosphinyl)-L-ornithine, PSOrn, and the nature of its binding to the OTCase enzyme was investigated using density functional (B3LYP) theory. The B3LYP/6-31G(d) calculations on the model compound, PSO, revealed that, while this molecule could be expected to exist in an amino form in the gas phase, on complexation in the active site of the enzyme it would be expected to lose two protons to form a dinegative imino tautomer. This species is shown to bind strongly to two H3CNHC(NH2)2+ moieties (model compounds for arginine residues), indicating that the strong binding observed between inhibitor and enzyme is partially due to electrostatic interactions as well as extensive hydrogen bonding (both model Arg+ residues form hydrogen bonds to two different sites on PSO). Population analysis and hydrogen bonding studies have revealed that the intramolecular bonding in this species consists of either single or semipolar bonds (that is, S and P are not hypervalent) and that terminal oxygens (which, being involved in semipolar bonds, carry negative charges) can be expected to form up to 4 hydrogen bonds with residues in the active site. In the course of this work several new G3 type methods were proposed, including G3MP4(SDQ) and G3[MP2(Full)], which are less expensive approximations to G3, and G3X2, which is an extension of G3X designed to incorporate additional electron correlation. As noted earlier, G3X2 shows a small improvement on G3X; G3MP4(SDQ) and G3[MP2(Full)], in turn, show good agreement with G3 results, with MAD�s of ~ 0.4 and ~ 0.5 kcal mol-1 respectively. 1. R. G. Hynes, J. C. Mackie and A. R. Masri, J. Phys. Chem. A, 1999, 103, 5967. 2. R. G. Hynes, J. C. Mackie and A. R. Masri, J. Phys. Chem. A, 1999, 103, 54. 3. R. G. Hynes, J. C. Mackie and A. R. Masri, Proc. Combust. Inst., 2000, 28, 1557. 4. N. L. Owens, Honours Thesis, School of Chemistry, University of Sydney, 2001. 5. A. Twarowski, Combustion and Flame, 1995, 102, 41.
26
Haworth, Naomi Louise. "Quantum Chemical Studies of Thermochemistry, Kinetics and Molecular Structure." University of Sydney. Chemistry, 2003. http://hdl.handle.net/2123/509.
Full textAbstract:
This thesis is concerned with a range of chemical problems which are amenable to theoretical investigation via the application of current methods of computational quantum chemistry. These problems include the calculation of accurate thermochemical data, the prediction of reaction kinetics, the study of molecular potential energy surfaces, and the investigation of molecular structures and binding. The heats of formation (from both atomisation energies and isodesmic schemes) of a set of approximately 120 C1 and C2 fluorocarbons and oxidised fluorocarbons (along with C3F6 and CF3CHFCF2) were calculated with the Gaussian-3 (G3) method (along with several approximations thereto). These molecules are of importance in the flame chemistry of 2-H-heptafluoropropane, which has been proposed as a potential fire retardant with which to replace chloro- and bromofluorocarbons (CFC�s and BFC�s). The calculation of the data reported here was carried out in parallel with the modelling studies of Hynes et al.1-3 of shock tube experiments on CF3CHFCF3 and on C3F6 with either hydrogen or oxygen atoms. G3 calculations were also employed in conjunction with the experimental work of Owens et al.4 to describe the pyrolysis of CFClBr2 (giving CFCl) at a radiation wavelength of 265 nm. The theoretical prediction of the dissociation energy of the two C-Br bonds was found to be consistent with the energy at which carbene production was first observed, thus supporting the hypothesis that the pyrolysis releases two bromine radicals (rather than a Br2 molecule). On the basis of this interpretation of the experiments, the heat of formation of CFClBr2 is predicted to be 184 � 5 kJ mol-1, in good agreement with the G3 value of 188 � 5 kJ mol-1. Accurate thermochemical data was computed for 18 small phosphorus containing molecules (P2, P4, PH, PH2, PH3, P2H2, P2H4, PO, PO2, PO3, P2O, P2O2, HPO, HPOH, H2POH, H3PO, HOPO and HOPO2), most of which are important in the reaction model introduced by Twarowski5 for the combustion of H2 and O2 in the presence of phosphine. Twarowski reported that the H + OH recombination reaction is catalysed by the combustion products of PH3 and proposed two catalytic cycles, involving PO2, HOPO and HOPO2, to explain this observation. Using our thermochemical data we computed the rate coefficients of the most important reactions in these cycles (using transition state and RRKM theories) and confirmed that at 2000K both cycles have comparable rates and are significantly faster than the uncatalysed H + OH recombination. The heats of formation used in this work on phosphorus compounds were calculated using the G2, G3, G3X and G3X2 methods along with the far more extensive CCSD(T)/CBS type scheme. The latter is based on the evaluation of coupled cluster energies using the correlation consistent triple-, quadruple- and pentuple-zeta basis sets and extrapolation to the complete basis set (CBS) limit along with core-valence correlation corrections (with counterpoise corrections for phosphorus atoms), scalar relativistic corrections and spin-orbit coupling effects. The CCSD(T)/CBS results are consistent with the available experimental data and therefore constitute a convenient set of benchmark values with which to compare the more approximate Gaussian-n results. The G2 and G3 methods were found to be of comparable accuracy, however both schemes consistently underestimated the benchmark atomisation energies. The performance of G3X is significantly better, having a mean absolute deviation (MAD) from the CBS results of 1.8 kcal mol-1, although the predicted atomisation energies are still consistently too low. G3X2 (including counterpoise corrections to the core-valence correlation energy for phosphorus) was found to give a slight improvement over G3X, resulting in a MAD of 1.5 kcal mol-1. Several molecules were also identified for which the approximations underlying the Gaussian-n methodologies appear to be unreliable; these include molecules with multiple or strained P-P bonds. The potential energy surface of the NNH + O system was investigated using density functional theory (B3LYP/6-31G(2df,p)) with the aim of determining the importance of this route in the production of NO in combustion reactions. In addition to the standard reaction channels, namely decomposition into NO + NH, N2 + OH and H + N2O via the ONNH intermediate, several new reaction pathways were also investigated. These include the direct abstraction of H by O and three product channels via the intermediate ONHN, giving N2 + OH, H + N2O and HNO + N. For each of the species corresponding to stationary points on the B3LYP surface, valence correlated CCSD(T) calculations were performed with the aug-cc-pVxZ (x = Q, 5) basis sets and the results extrapolated to the complete basis set limit. Core-valence correlation corrections, scalar relativistic corrections and spin orbit effects were also included in the resulting energetics and the subsequent calculation of thermochemical data. Heats of formation were also calculated using the G3X method. Variational transition state theory was used to determine the critical points for the barrierless reactions and the resulting B3LYP energetics were scaled to be compatible with the G3X and CCSD(T)/CBS values. As the results of modelling studies are critically dependent on the heat of formation of NNH, more extensive CCSD(T)/CBS calculations were performed for this molecule, predicting the heat of formation to be 60.6 � 0.5 kcal mol-1. Rate coefficients for the overall reaction processes were obtained by the application of multi-well RRKM theory. The thermochemical and kinetic results thus obtained were subsequently used in conjunction with the GRIMech 3.0 reaction data set in modelling studies of combustion systems, including methane / air and CO / H2 / air mixtures in completely stirred reactors. This study revealed that, contrary to common belief, the NNH + O channel is a relatively minor route for the production of NO. The structure of the inhibitor Nd-(N'-Sulfodiaminophosphinyl)-L-ornithine, PSOrn, and the nature of its binding to the OTCase enzyme was investigated using density functional (B3LYP) theory. The B3LYP/6-31G(d) calculations on the model compound, PSO, revealed that, while this molecule could be expected to exist in an amino form in the gas phase, on complexation in the active site of the enzyme it would be expected to lose two protons to form a dinegative imino tautomer. This species is shown to bind strongly to two H3CNHC(NH2)2+ moieties (model compounds for arginine residues), indicating that the strong binding observed between inhibitor and enzyme is partially due to electrostatic interactions as well as extensive hydrogen bonding (both model Arg+ residues form hydrogen bonds to two different sites on PSO). Population analysis and hydrogen bonding studies have revealed that the intramolecular bonding in this species consists of either single or semipolar bonds (that is, S and P are not hypervalent) and that terminal oxygens (which, being involved in semipolar bonds, carry negative charges) can be expected to form up to 4 hydrogen bonds with residues in the active site. In the course of this work several new G3 type methods were proposed, including G3MP4(SDQ) and G3[MP2(Full)], which are less expensive approximations to G3, and G3X2, which is an extension of G3X designed to incorporate additional electron correlation. As noted earlier, G3X2 shows a small improvement on G3X; G3MP4(SDQ) and G3[MP2(Full)], in turn, show good agreement with G3 results, with MAD�s of ~ 0.4 and ~ 0.5 kcal mol-1 respectively. 1. R. G. Hynes, J. C. Mackie and A. R. Masri, J. Phys. Chem. A, 1999, 103, 5967. 2. R. G. Hynes, J. C. Mackie and A. R. Masri, J. Phys. Chem. A, 1999, 103, 54. 3. R. G. Hynes, J. C. Mackie and A. R. Masri, Proc. Combust. Inst., 2000, 28, 1557. 4. N. L. Owens, Honours Thesis, School of Chemistry, University of Sydney, 2001. 5. A. Twarowski, Combustion and Flame, 1995, 102, 41.
27
Rogers, Sarah Elizabeth. "Fluorocarbon - hydrocarbon incompatibility in micellar polymerizations." Thesis, University of Bristol, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427908.
Full text
28
Herbert, Christopher James. "New routes to fluorocarbon-containing phosphines." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/new-routes-to-fluorocarboncontaining-phosphines(ef0db535-a854-48a2-89ea-fe9964629739).html.
Full textAbstract:
Routes to sterically demanding organofluorine-containing phosphines are described, and the stereoelectronic properties and chemistry of the resulting new ligands investigated. The synthesis of Cy2P(CF=CF2), 3, has been accomplished. The nucleophilic substitution of Ph2P(CF=CF2) with tBuLi produces the (Z)-isomer, Ph2P(Z-CF=CF(tBu)), 5-(Z), predominantly, which has been shown to be less electron-withdrawing than Ph2P(CF=CF2), and similar in size to 3. The bis-trifluoropropynyl substituted phosphine PhP(tfp)2, 7, has been prepared, and its reaction with tBuLi investigated. This results in the formation of three previously unknown species, the gem¬-difluorocyclopropenyl-containing compound, PhtBuP(dfcp), 8, (Z)-Ph2P(CH=C(t¬Bu)CF3), 9, and PhtBuP(tfp), 10. The nucleophilic substitution occurs preferentially at the phosphorus centre, as shown by the reaction with one equivalent of tBuLi at -60°C, where compounds 9 and 10 are formed. A new route to perfluoroalkyl-containing phosphines has been discovered. The addition of a perfluoroalkyl iodide to Ph2PSiMe3 results in the formation of six new phosphines, and has been shown to be extendable to partially fluorinated systems. The route can also be applied to iPr2PSiMe3, and to the chiral phosphine PhMePSiMe3. Three examples, Ph2PRf (Rf = CF(CF3)2, 15, (sC4F¬9), 18, (cyc-C6F11), 19), have been produced on a preparative scale. The reaction of the bis-trimethylsilyl phenyl phosphine with (CF3)2CFI has been investigated, though it does not result in the production of the bis-perfluoroalkyl-substituted phosphine, instead the previously unknown P-chiral compound, PhP(H)CF(CF3)2, 27 is formed. Mechanistic studies have indicated that Ph2P-PPh2 is the intermediate, and that there is no evidence of a radical mechanism. There is no reaction between Me2(S)P-P(S)Me2 and (CF3)2CFI, though there is when Me2P-P(S)Me2 is used, suggesting that the lone pair of the intermediate diphosphine is necessary for the reaction to proceed. This has resulted in the formation of the new compound, Me2PCF(CF3)2, 28. The chemistry of the perfluoroalkyl-containing phosphines has been investigated; they do not quaternise, but are oxidatively sensitive. The phosphorus(V) selenides of 15, 18, and 19 have been prepared, and based on their 1JPSe coupling constants, the perfluoroalkyl-groups impart a greater electron-withdrawing effect than perfluorovinyl, trifluoropropynyl, or alkoxy fragments. The oxidation of 15 and 18 with XeF2 has also been accomplished, and shown to yield the corresponding F2PPh2Rf compounds. The molybdenum(0) pentacarbonyl complexes of 3, 7, and 15 have been synthesised and perfluoroalkyl-groups have again been shown to be more electron-withdrawing than perfluorovinyl and trifluoropropynyl groups by comparison of v(CO) values. The gold(I) chloride complexes of Ph2PCF3, 15, and 18 and the platinum(II) dichloride complexes of 3 and 15 have been prepared, and the size of these ligands has been estimated from the crystal structures. Compound 18 has been shown to be the largest of these compounds, with a cone angle of 187°.
29
Astafyeva, Ksenia. "Physical and acoustical properties of fluorocarbon nanoparticles." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2014. http://tel.archives-ouvertes.fr/tel-00960290.
Full textAbstract:
In this thesis, acoustical and other physical properties of soft submicron suspensions were investigated in order to provide invaluable clues for their adaptation in theragnostic applications. Two types of dispersions were studied: fluorocarbon droplets stabilised with a polymeric (PLGA, PLGA-PEG) shell or a semifluorinated surfactant (called FTAC) shell. Since preparation of polymeric particles had been already developed, we first studied factors affecting mean diameter, size distribution, and coarsening of emulsions made of FTAC stabilising droplets of various fluorocarbons. Mechanical parameters used for emulsion synthesis and surfactants length were optimised to get the smallest droplets (~200 nm in diameter) that stay mainly submicrometric for several weeks. In addition, a full characterisation of surfactant properties was conducted. Next, for ultrasonic theragnostic purpose, it was necessary to improve our understanding in the mechanisms underlying interactions between ultrasonic waves and particles of a suspension. To do so, ultrasound propagation studies through dilute suspensions were carried out in a large frequency range (3-90 MHz) with subsequent modelling. The model could fit with a good accuracy our experimental data on polymeric particles and reveals information about unknown parameters of the shell: the geometrical parameters (shell thickness) and the viscoelastic parameters of the shell (speed of sound, shear moduli at infinite and zero frequencies, and the relaxation frequency). Therefore, such a model provides the required feedback for tuning the physicochemical parameters of nanoparticles in order to optimize their design.
30
Swales, Alan Peter. "Free-radical approaches to new fluorocarbon derivatives." Thesis, Durham University, 1989. http://etheses.dur.ac.uk/6555/.
Full textAbstract:
This thesis is concerned with the free-radical addition of nitrogen, silicon and oxygen containing compounds to fluoroalkenes and the chemistry of some of the adducts produced. Free-radical adducts of many amines cannot be produced directly since nucleophilic attack on the fluoroalkene is often the preferred reaction pathway. An alternative route to primary and secondary mono-amine adducts via N-trimethylsilylamines has been developed. An alternative synthesis of di-amine adducts via amides has met with some success. Free-radical additions of organosilicon compounds to fluoroalkenes have produced a variety of fluorosilicon adducts. The chemistry of some of these adducts has been investigated. Work with mono- and di-oxygen functional compounds has provided information on the scope and limitations of this type of free-radical addition reaction. The dehydrofluorination of ether/hexafluoropropene mono- and di-adducts has been investigated and some novel dienes have been produced. Polymers containing amide or ether groups added to hexafluoropropene under free-radical conditions. The use of a solvent dramatically increased the degree of this incorporation. The electrochemical fluorination of cyclic ether/hexafluoropropene di-adducts has been investigated. Good recoveries of highly fluorinated products were obtained, indicating that these types of adducts are good starting materials for electrochemical fluorination.
31
Rodenhurst, Paul Raymond. "Chemistry of diruthenium #mu#-alkenyl complexes." Thesis, University of Bristol, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385308.
Full text
32
Puntambekar, Smita. "Molecular self assembly in fluorocarbon surfactant/water systems." Thesis, University of Central Lancashire, 2000. http://clok.uclan.ac.uk/20906/.
Full textAbstract:
The work presented is a continuation of the study of a homologous series of tetrabutylammonium perfluoroalkylcarboxylate surfactants in water. These systems showed phase behaviour uncharacteristic of ionic perfluorocarbon surfactant systems in that they exhibit a clouding phenomenon with increasing temperature. This behaviour was ascribed to the tight association of the large, hydrophobic counterions with the poiar head group region. In this study a series of perfluorocarbon surfactants have been synthesised in which the hycirophobicity of the counterion is varied. The counterion is W (CH2CH2CH2CH3)(CH3) 41 whilst the surfactant ion remains unchanged throughout the series as periluorodecanoate. The number of butyl chains. 'n' controls the hydrophobicity of the counterion and, in these experiments, n = 4, 2, 1 and 0. The phase diagrams and the detailed phase structures have been investigated using optical polarising microscopy, 2H NMR spectroscopy and small angle x-ray scattering. As n decreases, the phase diagrams change, recovering the "generic" phase behaviour more usual for a perfluorocarbon surfactant - water system. X-ray measurements show that in the n = 4 (tetrabutylammonium perfluorodecanoate) system, all the phases (both liquid crystalline and non-liquid crystalline) have uniform mean interfacial curvature. The phases observed are L 1 (vesicles), L. and L 2. With decreasing counterion hydrophobicity, the population of counterions associated with the interface decreases, introducing greater curvature into the system. The mean curvature of the phase structures also becomes nonuniform. For n = 0 (tetramethylammonium perfluorodecarioate) no classical mesophases are observed. Much of the liquid crystalline region is taken up with a random mesh intermediate phase, Mh 1 (0) and an extensive rhombohedral mesh intermediate phase, Mh1 (R3 m). Phase behaviour intermediate between the two extremes is observed at n = 1 (butyltrimethylammonium perfluorodecanoate). In this system, the clouding phenomenon is not observed but there is a two phase region of L 1 + L. at low concentration and high temperatures. The phase structures also possess uniform mean curvature. In keeping with the less hydrophobic systems, the L. phase is less temperature sensitive at high concentrations. This work has shown that the but'l groups of the counterion are, in part, responsible for the unusual phase behaviour observed in the TBA surfactants. The hydrophobic nature of the counterion has a major impact on the structures formed even at high dilution. This nature probably drives the counterion to the interface which affects the type of mesophase formed at higher concentrations and also determines its stability with respect to temperature and concentration.
33
Mountford, Paul A. C. "Molecular Thermodynamics of Superheated Lipid-Coated Fluorocarbon Nanoemulsions." Thesis, University of Colorado at Boulder, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3721859.
Full textAbstract:
Diagnostic ultrasound is a safe, inexpensive and highly portable real-time imaging modality for viewing the human body. For over two decades, lipid-coated fluorocarbon microbubble contrast agents have been developed to help improve the diagnostic and therapeutic capabilities of ultrasound, but they have certain limitations. Recently, it was found that the microbubbles can be condensed into superheated liquid nanodrops capable of being vaporized by external optical or acoustic triggers. The compact form and vaporization effects of these phase-shift nanodrops may offer advantages over microbubbles for a number of current and future therapeutic and diagnostic applications. The goal of this dissertation work was to study the molecular thermodynamics and interfacial phenomena of these superheated phase-shift nanodrops.
In the first part of this work, a custom microscopy pressure chamber with control over temperature and pressure was used to observe microbubbles during condensation. Compression behaviors of fluorocarbon microbubbles constructed with lipid shells of varying acyl chain lengths were quantified over a broad temperature range. Microbubbles containing lipids of longer acyl chains were found to resist ideal compression and condensation. Dissolution was found to dominate as temperature approached the lipid main phase transition temperature, resulting in incomplete condensation. However, successful condensation of gas-filled microbubbles to liquid-filled nanodrops could be achieved at lower temperatures, and fluorescence microscopy showed that the lipid monolayer shell buckles and folds into surface-attached bilayer strands. The nanodrops were found to be remarkably stable when brought back to standard temperature and pressure. The temperature-pressure data were used to construct condensation phase diagrams to determine the thresholds for successful nanodrop formation.
In the second part of this study, the superheated nanodrops were vaporized back into microbubbles by changes in temperature and pressure. A custom optical chamber with control over temperature and pressure was used to track the kinetics of condensation, vaporization and dissolution of microbubble suspensions with varying fluorocarbon core and lipid shell compositions. A simple model was used to extract kinetic rates from the optical data, and Arrhenius plots were used to determine activation energies. The activation energy for thermal vaporization was found to vary with lipid acyl chain length, and a simple model of lipid intermolecular forces was used to explain this effect. Additionally, thermal vaporization was found to occur near 90% of the critical temperature of the fluorocarbon core, indicating that metastability of the superheated droplets was due to the low probability of homogenous nucleation rather than a Laplace overpressure. The superheated droplets could be reversibly vaporized and condensed to at least ten cycles, showing remarkable stability.
In the final part of this study, the tunability of vaporization was examined through the mixing of fluorocarbon gases in droplet core. A clinical ultrasound imaging system was used to track vaporization as a function of temperature and mechanical index. Discrepancies were found in the vaporization thresholds owing to mass transfer; the high solubility of the lower fluorocarbon caused it to rapidly deplete. However, a successful acoustic temperature probe was demonstrated. The experimental data from all three parts of this study were examined and explained by conventional molecular thermodynamics theory, providing new insights into the behavior and properties of these novel theranostic agents.
34
Mudumbi, John-Baptist Nzukizi. "Perfluorooctane sulfonate and perfluorooctanoate contamination of riparian wetlands of the Eerste, Diep and Salt Rivers." Thesis, Cape Peninsula University of Technology, 2012. http://hdl.handle.net/20.500.11838/2017.
Full textAbstract:
Thesis (MTech (Environmental Management))--Cape Peninsula University of Technology, 2012.Perfluorinated compounds (PFCs), in particular perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) have been found in aquatic environments throughout the world. Recent studies have reported that owing to their bioaccumulative nature, PFCs may also be present in various water sources, resulting in human and wild-life exposure. Although, these PFCs usually occur at low concentration levels, their presence in the environment has nevertheless been a concern in both developed and developing countries, since water remains an important natural resource for most living species. Water and sediment from rivers are one of the matrices in which PFC contamination is studied, since rivers receive water from various sources. However, limited studies have been conducted in South Africa on PFC contamination of river water and sediments. Although PFCs are sometimes unintentionally released into the environment, the concentration and type of PFCs that contaminate water sources vary among countries and depend on the types of industry releasing them into the environment, suggesting that PFC contamination patterns can be expected to differ from country to country, with PFOA and PFOS being the predominant perfluorinated contaminants. The aim of this study was therefore to determine the concentration of PFOS and PFOA in riparian wetlands of the Western Cape, focusing on the Eerste, Diep and Salt rivers, which are the primary rivers in the largest catchment areas of the Western Cape, South Africa.
35
Timmons, Christopher L. "Fluorocarbon Post-Etch Residue Removal Using Radical Anion Chemistry." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/10583.
Full textAbstract:
During fabrication of integrated circuits, fluorocarbon plasma etching is used to pattern dielectric layers. As a byproduct of the process, a fluorocarbon residue is deposited on exposed surfaces and must be removed for subsequent processing. Conventional fluorocarbon cleaning processes typically include at least one plasma or liquid treatment that is oxidative in nature. Oxidative chemistries, however, cause material degradation to next generation low-dielectric constant (low-k) materials that are currently being implemented into fabrication processes. This work addresses the need for alternative fluorocarbon-residue removal chemistries that are compatible with next generation low-k materials. Radical anion chemistries are known for their ability to defluorinate fluorocarbon materials by a reductive mechanism. Naphthalene radical anion solutions, generated using sodium metal, are used to establish cleaning effectiveness with planar model residue films. The penetration rate of the defluorination reaction into model fluorocarbon film residues is measured and modeled. Because sodium is incompatible with integrated circuit processing, naphthalene radical anions are alternatively generated using electrochemical techniques. Using electrochemically-generated radical anions, residue removal from industrially patterned etch structures is used to evaluate the process cleaning efficiency. Optimization of the radical anion concentration and exposure time is important for effective residue removal. The efficiency of removal also depends on the feature spacing and the electrochemical solvent chosen. The synergistic combination of radical anion defluorination and wetting or swelling of the residue by the solvent is necessary for complete removal. In order to understand the interaction between the solvent and the residue, the surface and interfacial energy are determined using an Owens/Wendt analysis. These studies reveal chemical similarities between specific solvents and the model residue films. This approach can also be used to predict residue or film swelling by interaction with chemically similar solvents.
36
Laschewsky, André, H. Ringsdorf, and G. Schmidt. "Polymerization of hydrocarbon and fluorocarbon amphiphiles in Langmuir-Blodgett multilayers." Universität Potsdam, 1985. http://opus.kobv.de/ubp/volltexte/2008/1709/.
Full textAbstract:
Langmuir-Blodgett multilayers of polymerizable carboxylic acids with hydrocarbon or fluorocarbon chains were prepared. The multilayers were polymerized by UV light and the reactions were studied by UV/visible spectroscopy. The polyreactions strongly influence the multilayer structures which were investigated by X-ray small-angle scattering and scanning electron microscopy. The spreading behaviour of the monomers, the preparation of multilayers, their reactivities in multilayers and structural effects caused by the polyreactions are discussed with regard to the hydrophilic head groups, the polymerizable groups and the hydrophobic chains.
37
Thompson, Richard Lewis. "Surfactant properties of semifluorinated alkanes in hydrocarbon and fluorocarbon solvents." Thesis, University of Hull, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363228.
Full text
38
Kwon, Ohseung 1969. "Surface kinetics modeling of silicon oxide etching in fluorocarbon plasmas." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28353.
Full textAbstract:
Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2004.Includes bibliographical references.
Fluorocarbon plasma for silicon oxide etching is a complicated system involving many ion and neutral species. Depending on the plasma condition, many difficulties arise such as RIE lag, etch stop, and low selectivity to photoresist. For a better understanding of the process it is necessary to have an appropriate physical model to describe the surface kinetics including simultaneous etching and deposition. A novel surface kinetic model, the translating mixed-layer (TML) model, has been developed. ABACUSS II, a modeling environment and simulator was used for solving differential algebraic equations that describes the surface kinetics. In the modeling, the effect of many variables were investigated including neutral and ion fluxes to the surface, sticking probabilities, surface composition, sputter etching reactions, ion enhanced chemical etching reactions and neutral-to-ion flux ratio. The model has been applied to various systems including silicon etching with chlorine chemistry, silicon oxide etching with fluorine chemistry and silicon oxide etching with fluorocarbon plasma. The verification of the model was done using measured etching yield data determined by quartz crystal microbalance (QCM) in conjunction with plasma neutral and ion concentrations/fluxes determined by mass spectrometry. The etching and deposition rates have been measured as functions of ion impinging angle, sample temperature, which are necessary for profile evolution modeling of silicon oxide etching in inductively coupled plasma. Angular dependence of etching yield of oxide in fluorocarbon plasma shows very unique behavior unlike typical ion-induced chemical etching or physical sputtering. Ion-induced deposition model was suggested and tested.
by Ohseung Kwon.
Sc.D.
39
Kobayashi, Hideki. "Preparation and surface properties of polysiloxanes with fluorocarbon side-chains /." Electronic version of summary, 1993. http://www.wul.waseda.ac.jp/gakui/gaiyo/1881.pdf.
Full text
40
Fisher, Craig Aaron. "Synthesis and structural features of α-fluorocarbonyl systems." Thesis, Durham University, 2018. http://etheses.dur.ac.uk/12510/.
Full textAbstract:
Molecules that bear carbon-fluorine bonds, especially on chiral centres, are becoming of interest to the pharmaceutical industry due to the effects on the bioactivity of a drug molecule. This thesis adds to the pool of chiral α-fluorocarbonyl systems and the discussion of the grey area surrounding their conformational preference. First, dimethyl 2-fluoromalonate was investigated as a nucleophile and as an electrophile. The fluorodiester was successfully reacted with a short series of electrophilic alkylating agents and, separately, a nucleophilic amine. Consequently, in collaboration with GlaxoSmithKline, these two strategies were combined to use dimethyl 2-fluoromalonate as a fluorinated ‘building block’ in the synthesis of a 6-membered fluorolactam. This fluorolactam subsequently underwent an enzymatic chiral resolution to yield an enantiomerically enriched analogue as an intermediate in the synthesis of a pre-clinical candidate spleen tyrosine kinase (Syk) inhibitor being developed by GSK. The process was optimised and quantitatively analysed by a ‘green metrics’ package developed by the EU IMI Chem21 consortium and found to be significantly less wasteful than the literature alternative synthetic route. Work on analogous 5- and 7-membered fluorolactams was carried out following the success of the 6-membered system. In collaboration with Almac Group, another α-fluorodicarbonyl species, ethyl 2-fluoroacetoacetate, was chosen as a substrate for carbonyl reductase (CRED) screening. Enzymatic routes to all four possible diastereomeric fluoroalcohol derivatives were found and work to determine the absolute stereochemistries of the products is ongoing. Following analysis of the structural preferences of the X-ray crystal structures of products developed in this thesis, the final chapter investigates the conformational preference of α-fluorocarbonyl moieties in the Cambridge Structural Database. This research was coupled with NMR experiments and computational calculations, from the literature and our own work, of these species in the solution state to determine that there is a greater syn F-C-C=O preference in more polar environments and that any inherent preference may potentially be overridden by a number of competing factors. The assumption that anti is the preferred conformation of α-fluorocarbonyl species must, therefore, be treated with caution.
41
Murthy, Shashi Krishna 1977. "Chemical vapor deposition and functionalization of fluorocarbon-organosilicon copolymer thin films." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/17038.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2003.Includes bibliographical references.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Neural prostheses are micron-scale integrated circuit devices that are under development for the treatment of brain and spinal cord injuries. A key challenge in the fabrication of these silicon- based devices is the protection of the electronic components from the ambient body environment. There is a need for a biopassivation coating on these devices that is chemically inert and electrically insulating with good adhesion to the underlying silicon substrate. Fluorocarbon-organosilicon copolymers are of interest for this application because they have the desirable attributes of both fluorocarbon and organosilicon polymers, such as low dielectric constant, thermal stability, and good adhesion to silicon. Chemical vapor deposition (CVD) is an attractive synthetic technique for this application because it is single-step, requires no solvent, and allows conformal coatings to be deposited on substrates with complex topographies and small dimensions. Fluorocarbon-organosilicon copolymers have been synthesized by hot-filament CVD, a thermal CVD technique. Control over deposition rate and chemical structure is achieved by precursor choice and variation of filament temperature. Chemical characterization by infrared (FTIR), x-ray photoelectron (XPS), and solid-state nuclear magnetic resonance (NMR) spectroscopies indicates that the copolymer films range from highly cross-linked films to flexible films comprised mostly of linear polymer chains. This variation in chemical composition influences physical properties such as thermal stability and flexibility. The possibility of creating bioactive surface coatings has been explored by using the techniques of CVD and solution chemistry in combination. Chains of poly(acrylamide) have been grafted onto fluorocarbon-organosilicon films as a first step towards the design of bioactive coatings that could potentially enhance the performance of medical implants.
by Shashi Krishna Murthy.
Ph.D.
42
Solomon, Meron. "Enhancing the durability of fluorocarbon-free Durable Water Repellant (DWR) formulation." Thesis, KTH, Skolan för kemivetenskap (CHE), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-213517.
Full textAbstract:
The focus of the project was to alter and optimize the water repellant textile coating formulations to reach enhanced durability. For this purpose, the project was approached with three methods. Firstly, bio-based components were implemented in the mother emulsion to act as surfactant and crosslinking agent and to provide hydrophobic properties. Secondly different binders were added to crosslink and increase the coating resistance towards washes. Lastly additives at nano-scale were added to increase surface roughness in order to obtain higher hydrophobicity and improved of crosslinking capacity due to the presence of more functional groups. The stability of all emulsions was controlled using different techniques such as optical microscopy to determine particle size, distribution and any observable instability (flocculation etc.), normal aging at room temperature and accelerated aging using higher temperature. All coatings were applied using a laboratory padder on standard PA and PES pieces of textiles and hydrophobic performance was evaluated through ISO 4920 spray test. By standard washing and repeating spray test, durability could be assessed. Further structure and property studies have been run using other tests such as: contact angle measurement, breathability of the coating and SEM observations. Based on the obtained results the incorporation of low HLB, bio-based surfactants in low amount (~0,25%) resulted in an increase in the hydrophobic performance of the tested textiles. However, a decrease in shelf life could be observed with these surfactants at room temperature. Sonication was successfully used to increase both stability and shelf life significantly. Some binders and nanoparticles proved to be successful in increasing the coating quality and thus the durability. Overall many of the developed formulations could enhance performance on PA compared to the already present commercial product. On PES textile, however, the developed strategies yielded hydrophobic effect close to the commercial product.
43
Mayot, Estelle. "Monobactames et triazoles fluorocarbonés amphiphiles : vers des systèmes catanioniques à propriétés multiples." Nancy 1, 2007. http://docnum.univ-lorraine.fr/public/SCD_T_2007_0136_MAYOT.pdf.
Full textAbstract:
Les travaux présentés dans ce mémoire sont consacrés à la conception et à l’étude de nouveaux systèmes catanioniques bioactifs originaux, formés à partir de deux tensioactifs de charges opposées, apportant chacun une propriété biologique spécifique complémentaire de l’autre, susceptible d’engendrer une synergie. Dans un premier temps, sur la base de travaux antérieurs, nous avons réalisé la synthèse de monobactames amphiphiles ionisables présentant une HLB facilement modulable par greffage d’un motif polyéthoxylé. Les propriétés physico-chimiques particulières des tensioactifs fluorocarbonés nous ont incités à synthétiser des composés de type b-aminoacides perfluorés, précurseurs de cycles lactames. Dans un deuxième temps, nous avons étudié la synthèse de divers triazoles, porteurs également d’une chaîne perfluorée, par le biais d’une cycloaddition 1,3 dipolaire ou d’une cyclisation intramoléculaire. Les études physico-chimiques de chacun des tensioactifs parents, notamment par mesure de la tension superficielle, ont révélé une grande activité de surface pour tous les composés. Une série de systèmes catanioniques a ensuite été préparé en associant deux amphiphiles par interaction ionique, et plus particulièrement un dérivé de type triazole et un de type monobactame. La mesure de leur capacité tensioactive a montré d’intéressants phénomènes de synergie. Une étude préliminaire de leurs propriétés antibactériennes a donné des résultats encourageants. Enfin, le fort potentiel des amphiphiles fluorés nous a conduit à nous intéresser à d’autres structures fluorocarbonées, dérivées d’a-aminoacides et d’imines, qui pourront par la suite être engagées dans un système catanioniqueIn the work presented in this thesis, we were interested in the conception and in the study of original catanionic systems, constituted by ionic interaction between two surfactants with opposed charges, each one bringing a specific biological property. Firstly, we synthesised different amphiphilic ionisable monobactams, with an easily flexible HLB by addition of a polyoxyethylene part. Particular physico-chemical properties of highly fluorinated surfactants led us to synthesised perfluorinated b-aminoacid, which are precursors of lactams cycles. Secondly, we studied the synthesis of different 1,2,3-triazoles, also with a perfluorinated chain, via a 1,3 dipolar cycloaddition or an intramolecular cyclisation. The physico-chemical studies of each parent surfactant, notably by the measure of the surface tension, revealed a high tensioactive power for every compound. Different catanionic systems were prepared afterwards by associating two surfactants with opposed charges, particularly a triazole and a monobactam. The measure of their tensioactive activity showed interesting synergistic effects. A preliminary study of their antibacterial properties gave promising results. Eventually, the high potential of fluorinated amphiphiles led us to the interest of other perfluorinated structures, some a-aminoacids and some imines, which could be engaged in a catanionic system study at a later date
44
Agraharam, Sairam. "Plasma assisted deposition of low dielectric constant fluorocarbon materials for microelectronic applications." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/11896.
Full text
45
Grunenberg, Alfred Teo. "Separation of fluorocarbon gases from a reactor plasma system / Alfred Teo Grunenberg." Thesis, North-West University, 2008. http://hdl.handle.net/10394/2640.
Full textAbstract:
South Africa has natural resources in mineral feedstock containing gold, manganese, chromium, vanadium, copper, antimony, phosphate rock, uranium, fluorspar and titanium. A high percentage of these ores are exported in unbeneficiated form. There are beneficiation opportunities to transform the raw materials to value-added products, thus increasing employment and stimulating the South African economy.
Fluorocarbon (CxFy) gases can be produced via high-temperature plasma processes, where fluorspar and carbon (CaF2 + C) react at -6000K. These gases are traditionally separated by means of costly and unsafe cryogenic distillation.
The focus of this project is to propose a feasible separation process and to interlink it to a plasma system in order to develop a conceptual plant that can produce 2500 t/a C2F4 and 625 t/a C3F6 safely and cost-effectively, both with 96% purity.
To execute the above a literature survey was done giving vital information on absorption and distillation systems as well as membranes that can be used to separate CF4 from CxFy gas streams at acceptable pressures and temperatures.Thesis (M.Sc. Engineering Sciences (Chemical Engineering))--North-West University, Potchefstroom Campus,
46
Nothnagel, Carien. "Multivariate data analysis using spectroscopic data of fluorocarbon alcohol mixtures / Nothnagel, C." Thesis, North-West University, 2012. http://hdl.handle.net/10394/7064.
Full textAbstract:
Pelchem, a commercial subsidiary of Necsa (South African Nuclear Energy Corporation), produces a range of commercial fluorocarbon products while driving research and development initiatives to support the fluorine product portfolio. One such initiative is to develop improved analytical techniques to analyse product composition during
development and to quality assure produce.
Generally the C–F type products produced by Necsa are in a solution of anhydrous HF, and cannot be directly analyzed with traditional techniques without derivatisation. A technique such as vibrational spectroscopy, that can analyze these products directly without further preparation, will have a distinct advantage. However, spectra of mixtures of similar compounds are complex and not suitable for traditional quantitative regression analysis.
Multivariate data analysis (MVA) can be used in such instances to exploit the complex nature of spectra to extract quantitative information on the composition of mixtures.
A selection of fluorocarbon alcohols was made to act as representatives for fluorocarbon compounds. Experimental design theory was used to create a calibration range of mixtures
of these compounds. Raman and infrared (NIR and ATR–IR) spectroscopy were used to
generate spectral data of the mixtures and this data was analyzed with MVA techniques by
the construction of regression and prediction models. Selected samples from the mixture
range were chosen to test the predictive ability of the models.
Analysis and regression models (PCR, PLS2 and PLS1) gave good model fits (R2 values larger
than 0.9). Raman spectroscopy was the most efficient technique and gave a high prediction
accuracy (at 10% accepted standard deviation), provided the minimum mass of a
component exceeded 16% of the total sample.
The infrared techniques also performed well in terms of fit and prediction. The NIR spectra were subjected to signal saturation as a result of using long path length sample cells. This was shown to be the main reason for the loss in efficiency of this technique compared to Raman and ATR–IR spectroscopy.
It was shown that multivariate data analysis of spectroscopic data of the selected
fluorocarbon compounds could be used to quantitatively analyse mixtures with the
possibility of further optimization of the method. The study was a representative study
indicating that the combination of MVA and spectroscopy can be used successfully in the
quantitative analysis of other fluorocarbon compound mixtures.Thesis (M.Sc. (Chemistry))--North-West University, Potchefstroom Campus, 2012.
47
Limb, Scott J. (Scott Jong Ho). "Pulsed plasma enhanced and pyrolytic chemical vapor deposition of fluorocarbon biopassivation coatings." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10412.
Full text
48
Lee, Graham Mark. "Fluorocarbene, Fluoroalkyl, and Fluoride Complexes of First-Row Transition Metals." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36704.
Full textAbstract:
Fluorinated organic compounds play important roles in our society, as these products range from life-saving pharmaceuticals and agrochemicals, to fluoropolymers with extremely high thermal and chemical stability. Although elemental fluorine (F2) is the most reactive element, some fluoro-organic compounds are chemically inert. As such, controlled reactivity of fluorine or highly-fluorinated organic fragments is a considerable, yet important challenge for synthetic chemists.
Fluoro-organometallic chemistry has been studied for decades, as researchers attempt to maximize the potential of metal mediated/catalyzed processes for the synthesis of fluorinated organic molecules. Within this framework, metal fluorocarbene complexes are particularly interesting because of their highly tunable reactivity, and are proposed for use in important metathesis/polymerization reactions of perfluorinated alkenes. While considerable work is still needed to make these proposed reactions a reality, this thesis outlines contributions from our research group. We showed that cobalt fluorocarbene complexes CpCo(=CFRF)(PPh2Me) (RF = F, CF3) undergo [2+2] cycloaddition reactions with tetrafluoroethylene (TFE) and phenylacetylene to form perfluorometallacyclobutane and partially fluorinated metallacyclobutene products, respectively. For both reactions, computational studies reveal a stepwise ring-closing mechanism, which proceeds through a singlet 1,4-diradical intermediate.
Next, the formation of CpCo(=CF2)(L) complexes is achieved via the direct addition of difluorocarbene, generated in situ, to a cobalt(I) precursor. Subsequent addition of CF2 to cobalt fluorocarbene complexes results in [2+1] cycloaddition and formation of perfluorinated alkene complexes. The [2+1] addition is highly favored as the cobalt fluorocarbenes readily react with electrophilic CF2. A series of experiments provide evidence for the stepwise nature of fluoroalkene complex formation.
From Co(I) fluorocarbene complexes, the focus shifts to preparing metal fluorocarbenes with electrophilic-type reactivity. The synthesis of bis(perfluoroalkyl) complexes serve as precursors for preparation of perfluoroalkyl cobalt(III) fluorocarbenes, which undergo migratory insertion reactions of the fluorocarbene into the perfluoroalkyl ligand. Using a similar synthetic approach, nickel(II) and palladium(II) difluorocarbene complexes are prepared from their corresponding trifluoromethyl precursors.
The synthesis, characterization and reactivity of cobalt(III) fluoride complexes is also described, including the catalytic fluorination of acyl chlorides, demonstrating the first example of a cobalt(III) catalyzed fluorination reaction. The effects of the various ancillary ligands on these cobalt catalysts are investigated using high-throughput experimentation technology, and the scope of the reaction is expanded to include the synthesis of a variety of acyl fluoride compounds.
Finally, the results and learnings from this work will be summarized and highlighted. The future directions and novel research which could result from the continuation of these projects is discussed, with an emphasis placed on the areas believed to have the highest potential impact.
49
Fukumoto, Hiroshi. "Model Analysis of Plasma-Surface Interactions during Silicon Oxide Etching in Fluorocarbon Plasmas." 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/158076.
Full text
50
Lau, Kenneth Ka Shun 1972. "Chemical vapor deposition of fluorocarbon films for low dielectric constant thin film applications." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/16748.
Full textAbstract:
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2000.Includes bibliographical references.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Pulsed plasma enhanced and hot filament chemical vapor deposition have produced fluorocarbon films with the potential use as low dielectric constant interconnect materials in microelectronic circuits. Solid-state nuclear magnetic resonance spectroscopy was demonstrated as a valuable film characterization tool to understand structure-property processing fundamentals, quantifying film bonding environments and tracing structural instabilities. Thermal lability in fluorocarbon films was attributed to terminal end groups and low molecular weight molecules. High temperature thermal stability was achieved by minimizing such labile sources through a clean deposition of high molecular weight chains of poly(tetrafluoroethylene). Poly(tetrafluoroethylene) film porosity was introduced and controlled through the competition between nucleation and growth of film. Porous poly(tetrafluoroethylene) films were further integrated into a bridge layer and air gap dielectric interconnect scheme. With fluorocarbon materials deposited through such chemical vapor deposition methods, dielectric constants ranging from 2.1 to below 1.5 were conceivably attainable, thus potentially satisfying dielectric interconnect requirements to beyond the 0.1 [mu]m technology node.
by Kenneth Ka Shun Lau.
Ph.D.