Ce travail porte sur le greffage radicalaire de l'anhydride maléique sur un polyéthylène basse densité, en voie fondu, et en présence d'un abstracteur d'atome d'hydrogène. L'utilisation des radicaux nitroxyle, comme agent de terminaison, en présence d'un peroxyde a permis de bloquer la réaction de réticulation du polyéthylène, réaction secondaire fréquemment rencontré lors de l'utilisation de radicaux peroxyle, tout en permettant le greffage d'une faible quantité d'anhydride maléique. L'élimination d'une partie de l'anhydride maléique et des radicaux nitroxyle via des réactions secondaires à haute température semble toutefois inévitable. La substitution du peroxyde par une alcoxyamine dans le rôle d'abstracteur d'atome d'hydrogène a alors permis d'atteindre des taux de greffage en anhydride maléique supérieurs pour une modification des propriétés rhéologiques du polyéthylène équivalente. Néanmoins, des incertitudes demeurent encore sur le mécanisme de décomposition thermique de cette alcoxyamine permettant la réaction de greffage. / This work deals with melt grafting of maleic anhydride onto low density polyethylene using radical initiators which are able to abstract hydrogen from the polyolefin backbone. The use of a nitroxide radical as a termination reagent in presence of peroxide allowed to prevent the polyethylene crosslinking during the maleic anhydride grafting. Indeed, the polyethylene crosslinking is the main side reaction but the elimination of a small proportion of the reagents (monomer and nitroxide radical) through other side reactions seems to be unavoidable. The peroxide substitution by an alcoxyamine leaded to a higher grafted maleic anhydride rate for the same polyethylene rheological modification. Nevertheless, the thermal decomposition mechanism of the alcoxyamine which makes the grafting reaction possible is still uncertain.

1,8-bis(phenylimino)-3,6-ditertbutyl-carbazole is synthesized and characterized, which can be complexed with copper(II) halide by deprotonation and transmetallation. The resulting copper complexes enable to polymerize MMA through RATRP process.

We reported a non-crosslinking approach to synthesize nitroxide radical polymer brushes for thin-film electrodes via surface-initiated atom transfer radical polymeization (SI-ATRP), which was effective to yield the organic radical polymer brushes with high grafting density and to attain a uniform surface. As mentioned above, the covalent bonding of nitroxide polymer brushes to the conducting substrate not only prevented the polymer dissolution into organic electrolyte solution but improved the cycle life performance of batteries. Moreover, they can be the potential application in microbatteries by using microcontact printing to produce the patterned nitroxide polymer brushes on a conducting substrate. Even though the organic radical polymer brushes provided a new approach to syn-thesize thin-film electrodes, they still existed many problems that needed to study and to figure out. We discussed the morphology and electrochemical performance about ni-troxide radical polymer in the thesis. In the measurement of surface properties, we used the contact angle, electron spectroscopy for chemical analysis (ESCA) and atomic force microscopic (AFM) to proceed. Another, in the measurement of electrochemical analysis, we used the cyclic voltammetry(CV), alternating current (AC) impedance and charge-discharge to understand the regarding mechanism in this polymer layer during the electrochemical reaction. In chapter 4, we discussed the oxidative problem in the polymer brushes. It should be well controlled during the oxidation reaction, because the oxidation level may affect the diffusion of electron that resulted the capacity better or not. In chapter5, we controlled the density of polymer brushes to construct the possible mechanism during the electro-chemical reaction, and found out the possible factors that affected the electrochemistry. In chapter 6, we applied the better results from the front chapter to the organic radical battery, and compared their electrical performance.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The interest in antioxidants has increased considerably in recent years as molecules that reduce lipid peroxidation may minimize or inhibit the oxidative damage caused to DNA, proteins and carbohydrates. Flavonoids, a group of secondary metabolites widely distributed in the plant kingdom, have properties of anti-inflammatory, antibacterial, antiviral, anti-allergic and anti-tumor, in addition to possessing antioxidant and free radicals to inactivate them and prevent oxidative damage at cell level. It is believed that the biological activity of flavonoids is due to its antioxidant properties. Due to the great importance given today to free radicals and antioxidants, there is a strong demand for analytical techniques able to identify and quantify these two groups of compounds. This work describes the study of anti-radical power of the flavonoids kaempferol, fisetin, quercetin, quercitrin, myricetin and rutin against UV radiation and HO radical. The method used was based on artificial photochemical generation of HO radicals by photolysis of H2O2. The flavonoids studied were photpstable towards UV radiation and efficient in the fight against HO radical. The flavonoid quercitrin was the most active compound, followed by rutin, kaempferol, fisetin, quercetin and myricetin. The proposed methodology allows for quantitative comparison of the antiradical action of the antioxidants based on the reaction kinetics of the species with the HO radical. Similarly, the study in vitro the interaction between HO radicals and plant extracts with antioxidant character can be accomplished by the proposed method. / O interesse por substâncias antioxidantes aumentou consideravelmente nos últimos anos, pois moléculas que diminuem a peroxidação de lipídeos podem minimizar ou inibir os danos oxidativos causados ao DNA, proteínas e carboidratos. Os flavonóides, um grupo de metabólitos secundários, amplamente distribuídos no reino vegetal, apresentam propriedades antiinflamatórias, antibacterianas, antivirais, antialérgicas e antitumorais, além de possuírem propriedades antioxidantes sobre radicais livres de forma a inativá-los e a prevenir os danos oxidativos em nível celular. Acredita-se que a atividade biológica dos flavonóides seja devido às suas propriedades antioxidantes. Devido à grande importância dada atualmente aos radicais livres e antioxidantes, existe uma forte demanda por técnicas analíticas capazes de identificar e quantificar esses dois grupos de compostos. Este trabalho descreve o estudo do poder anti-radicalar dos flavonóides canferol, fisetina, quercetina, quercitrina, miricetina e rutina frente à radiação UV e ao radical HO . O método empregado baseou-se na geração fotoquímica artificial do radical HO pela fotodecomposição do H2O2. Os flavonóides estudados foram fotoestáveis frente à radiação UV e eficientes no combate ao radical HO . A quercitrina foi o flavonóide com maior ação anti-radicalar, seguida da rutina, canferol, fisetina, quercetina e miricetina. A metodologia proposta possibilita a comparação quantitativa da ação anti-radicalar de antioxidantes com base na cinética de reação das espécies com o radical HO . Da mesma forma, o estudo in vitro da interação entre radicais HO e extratos de plantas com caráter antioxidante pode ser realizado pelo método proposto.

The importance of radical-water complexes in the atmosphere is explored in this dissertation. Radicals, although present in small concentrations in the atmosphere, play a significant role in creating and removing atmospheric pollution. As the atmosphere warms and consequently gets wetter, it is essential to understand the effects of water vapor on radical chemistry. This dissertation reports studies on the effects of water vapor on the kinetics of the self-reaction of β-hydroxyethyl peroxy radical (β-HEP), a prominent organic peroxy radical in the atmosphere. Both experimental and computational studies have been performed to examine the effects of water vapor on the kinetics of the self-reaction. The influence of water vapor and temperature on the reaction rate constant is presented. The rate of the self-reaction increases between 2 to 6 times with an increase in water vapor and decrease in temperature. The products of the self-reaction in the presence and absence of water vapor have been computed using high level ab initio calculations. Major products include alkoxy radicals, peroxides, aldehydes, alcohols and oxygen. A new reaction pathway leading to formation of hydroperoxy radical (HO2) from the self-reaction of β-HEP in the presence of water vapor was identified. In the presence of high NOx concentration HO2, forms tropospheric ozone, which is classified as a harmful pollutant by the Environmental Protection Agency (EPA). Like tropospheric ozone, aerosols are also classified as harmful pollutants by the EPA. Sulfuric acid-water complexes are estimated to be the primary reason for new aerosol formation in the atmosphere. However, the sulfuric acid concentration in the atmosphere alone is not sufficient to account for observed aerosol concentrations. Classical nucleation theory is used to explain new particle formation (NPF), which is initiated by the formation of a nucleating site (a highly polar complex). This dissertation explores the role of various radical-molecule complexes acting as the nucleating site. Experimentally, the HO2-water complex is studied as a possible nucleating site for NPF. A new instrument was developed to create and measure radical-water complex initiated particle formation. The instrument incorporates two scanning mobility particle sizers (SMPS) to measure the size distribution and number density of the aerosol particles formed. The experimental setup uses UV absorption spectroscopy and wavelength modulated spectroscopy to measurethe HO2 radical and water vapor concentrations in the reaction cell. No significant particle formation was observed at room temperature and pressure. Particle formation from the HO2-water complex, may occur at lower temperatures. Additional radical-molecule complexes have been studied computationally in an effort to identify other possible nucleating sites for particle formation. In particular, the complexes of sulfuric acid, nitric acid, acetic acid and formic acid with ammonia, amidogen radical (NH2) and imidogen radical (NH) have been studied. H2SO4-NH2 and HNO3-NH2 complexes show the potential to act as nucleating sites for formation of aerosol particles in the atmosphere. In summary, water mediated chemistry plays a significant role in the atmosphere and must be included in scientific models to better predict pollution levels in the atmosphere.

Thesis (MA)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The transhumanist movement propounds the view that the evolution of humanity must be extricated from the contingencies of blind natural selection and actively directed by human beings themselves, utilising existing as well as nascent technologies, in order to radically enhance and thus transform individual human capabilities to levels which far surpass current capacities. Transhumanism has elicited vehement critique, however, due to the claim that the transformations it proposes will result in a new posthuman species; and thus, that its aims represent a violation of human dignity. In order to assess this claim it is necessary to firstly investigate the aims and values of the transhumanist movement, as well as the technological means through which it proposes these aims will be fulfilled. This task is the focus of the first half of this thesis. Secondly, the concept of dignity itself must be examined in order to ascertain its status as a means of critiquing transhumanism. The second half of this thesis therefore explicates the notion of dignity by tracing its historical interpretations and uses, as well as the way in which it has been employed to uphold human rights and to adjudicate bioethical dilemmas in the contemporary milieu. This investigation enables the assessment of the two most renowned dignity arguments, namely, the arguments of the bioconservative thinkers Leon Kass and Francis Fukuyama which have been lodged against transhumanism, as well as the counter-argument of the transhumanist Nick Bostrom. In light of this discussion, the conclusion is that the notion of dignity is plagued by irrevocable ambiguity, vagueness and inconsistencies, due to the presence of conflicting interpretations. These findings have implications for the concept’s efficacy to adjudicate the complex ethical conundrums posed, not only by transhumanism, but in the bioethics arena in general. / AFRIKAANSE OPSOMMING: Die transhumanistiese beweging verteenwoordig die standpunt dat die evolusie van die mensdom losgemaak moet word van die toevallighede van blinde, natuurlike seleksie en aktief gerig moet word deur die mens self, deur van bestaande sowel as ontwikkelende tegnologieë gebruik te maak ten einde individuele menslike vermoëns radikaal te verbeter en dus te transformeer tot op vlakke wat huidige vermoëns ver oorskry. Transhumanisme het egter hewige kritiek ontlok weens die aanspraak dat die transformasies wat dit voorstel ‘n nuwe post-menslike spesie tot gevolg sal hê en dus dat die oogmerke daarvan ‘n skending van menswaardigheid verteenwoordig. Ten einde hierdie aanspraak te beoordeel, was dit eerstens nodig om die oogmerke en waardes van die transhumanistiese beweging te ondersoek, sowel as die tegnologiese middele wat voorgestel word as dit waardeur hierdie oogmerke verwesenlik sal word. Hierdie taak is onderneem in die eerste helfte van die tesis. Tweedens is die konsep van waardigheid self krities onder die loep geneem ten einde die status daarvan as ‘n middel om transhumanisme te kritiseer, te beoordeel. Die tweede helfte van hierdie tesis verhelder dus die idee van waardigheid deur die historiese interpretasies en gebruike daarvan na te gaan, sowel as die manier waarop dit aangewend is om menseregte te ondersteun en om dilemmas in die bioetiek in die hedendaagse milieu te bereg. Hierdie ondersoek maak die beoordeling van die drie mees bekende waardigheidsargumente wat teen transhumanisme gebring is, naamlik die argumente van die biokonserwatiewe denkers Leon Kass en Francis Fukuyama, sowel as die teenargument van die transhumanis Nick Bostrom, moontlik. Na aanleiding van hierdie bespreking is die gevolgtrekking van die skrywer dat die idee van menswaardigheid deurspek is met onvermydelike dubbelsinnigheid, vaagheid en teenstrydighede as gevolg van teenstrydige interpretasies. Hierdie bevindinge het implikasies vir die doeltreffendheid van die konsep om die komplekse etiese probleme wat gestel word, nie net deur transhumanisme nie, maar deur die bioetiek arena oor die algemeen, te beoordeel.

Progression d'un concept, le mal radical, dans trois textes : La Religion dans les limites de la simple raison (Kant), Le système de l'Ethique (Fichte), et Le Traité de 1809 (Schelling). Origine ultime du mal : libre arbitre ou détermination ? Responsabilité et liberté du mal. Mal moral et métaphysique du mal/ Advance of a concept: radical evil, in three readings: Religion within the Limits of Mere Reason (Kant), System of Ethics (Fichte), and Treatise of 1809 (Schelling).Ultimate origin of evil: free will or determination? Responsibility and freedom to evil. Moral evil and metaphysics of evil.

Radical polymerisation (RP) has for many years been an industrially important process, and the kinetics of the process remains an active area of research. As polymerisation proceeds, converting monomer (small molecules) into polymer (long chain molecules), chemical species of a variety of chain lengths are produced. Recent work has pointed toward the fact that rate coefficients for polymerisation reactions (specifically, termination and propagation) are often dependent on the chain-length of the reacting species. The focus of this thesis is to study the effects of chain-length-dependent reactions on the kinetics of RP, by using computer-based modeling and comparing the results of such modeling with experimental data. This enables the understanding of otherwise inexplicable trends and the building of more mechanistically detailed and accurate models for RP kinetics. In Chapter 2, a new model for termination is developed, connecting observations and analyses of termination kinetics at short chain lengths (particularly small molecule studies) with other observations and analyses at long chain lengths (conventional RP kinetics studies) in order to construct a model for termination that is shown to be capable of coherently describing termination kinetics at any chain length. In Chapter 3, this new model for termination is tested at short chain lengths on polymerisations with large quantities of added chain transfer agent. With the inclusion of chain-length-dependent propagation in the model, the model for termination is validated. Chapter 4 is aimed at extending an existing reduced-variable, compact, 'universal' description of steady-state RP kinetics by incorporating all known chain-length dependent reactivities. This both increases computational efficiency over other approaches and provides easily evaluated, approximate analytical expressions for RP kinetics. This foundational theory is applied in Chapter 5 to reach a deeper understanding of the behaviour of the model, and show how experimental data may readily be analysed to extract information about chain-length-dependent termination kinetics. In Chapter 6, the effect of chain-length dependent reactivities on the important technique of single-pulse pulsed-laser polymerisation is investigated, and this technique is validated as the best experimental method for investigation of termination kinetics. In general, a central result of this thesis is that chain-length-dependent reactivities, when acknowledged and properly incorporated into models, can explain many phenomena in RP kinetics which otherwise seem difficult to account for. No exceptions to this principle have been found.

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