The work described in this thesis is concerned with three areas which are the generation of stable carbocations from saturated model compounds related to poly- vinylidenefluoride, the development of synthetic routes to fluoro-organo-phosphazenes with intention of obtaining some potential additives for perfluoropolyether fluids operating at elevated temperatures, and pericyclic reactions involving fluorinated olefins.1. We reported that some remarkable conjugated cations, and di-cations (4a) are obtained by reaction of hydrofluorocarbon precursors (4) with an excess of antimony pentafluoride. Cations (4a) bear the fluorine atoms at the charged sites, which of course, leads to stabilisation of the systems We investigated the effect of both re-hybridisation and charge on (^13)C, (^19)F, (^1)H n.m.r. chemical shifts and we applied the empirical criterion of (^13)C chemical shifts additivity to these systems to confirm the structure of some carbo-mono-cations and.-di- cations.2. The mechanism of displacement reactions in halophosphazenes was rationalised by reacting the systems in study with selected nucleophiles in competition reactions. Some fluoro-organo-phosphazenes were synthesised using halophosphazenes as starting materials. Different methodologies were used and their effectiveness was limited by the reactivity of the halophosphazenes towards the fluoroalkylating agents. The methodologies used include nucleophilic displacement of the halogen with fluorinated alcohols (R(_F)CH(_2)OH), and perfluoroalkylating agents (eg.: CF(_3)SiMe(_3)); perfluoroalkylation of organo-phosphazene using hexafluoropropene under gamma ray irradiation. Potential stabilising agents for perfluoropolyether fluids were synthesised and their effectiveness was tested.3. Some pericyclic reactions of heptafluorobut-2-ene and hexafluorobut-2-ene with dienes have been studied in an attempt to synthesise a series of benzenoid and heteroaromatic compounds containing two trifluoromethyl groups in high yields.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

The use of waste gas such as carbon dioxide (CO2) to prepare useful and valuable polymers benefits both the economy and the environment. Various strategies have been developed to reduce CO2 emission as well as to transfer CO2 into high-value products. CO2/epoxide copolymerization is one of the most promising methods of not only reducing the CO2 emission from the atmosphere but also producing biodegradable CO2-based materials that are CO2 as source-abundant, renewable, cheap, non-flammable and non-toxic. However, the activation of CO2 is one of several problems associated with the polymerization of CO2 due to its stability as a thermodynamic end product. Herein, my dissertation describes the effectiveness of new lithium/phosphazene complexes to generate highly active species for CO2/epoxide copolymerization and to capture/activate CO2 molecules for the nucleophilic attack of the active species. Well-defined polycarbonates and polycarbonate-based block copolymers are produced that have control of molecular weights, unimodal distributions and narrow molecular weight distributions (Chapter 3 and 4). Besides, these complexes provide access to prepare CO2-based triblock copolymers that are powerful candidates to serve as the next generation of thermoplastic elastomers (Chapter 4). Additionally, these complexes are applied for the anionic polymerization of petrochemical-based sources such as styrene and dienes producing polymers in faster rate of polymerization with control of molecular characteristics (Chapter 2). A general introduction of polymers and their classification based on composition, chemical structure, mechanical properties, degradability, source, applications, and preparative methods, is covered in Chapter 1

No description available.

Le phosphure d’indium (InP) est un semiconducteur III-V aux propriétés adaptées aux applications optoélectroniques. Toutefois, son oxydation spontanée à l’air engendre une dégradation de ses propriétés électriques. La passivation de sa surface devient donc une étape clé pour son intégration dans des dispositifs optoélectroniques attractifs. Dans le cadre de ce travail de thèse, nous nous sommes intéressés à l’étude de la passivation de surface de InP par nitruration. Nous avons réalisé de manière reproductible la formation d’un film de type polyphosphazène ( H2N-P=NH )n sur InP par voie électrochimique dans l’ammoniac liquide (-55°C). Le suivi de la croissance du film sur InP a été effectué grâce au couplage systématique de mesures électrochimiques (J = f(E), J = f(t), E = f(t) et C = f(E)) avec des analyses de composition chimique de surface par XPS (X-ray photoelectron spectroscopy). Chacune de ces techniques apporte des éléments sur la compréhension du mécanisme de nitruration de la surface de InP en solution (anodisation en milieu NH3 liq), nous permettant ainsi de proposer un mécanisme de formation du film de phosphazène de type ECE « Electrochimique-Chimique-Electrochimique ». L’étude par XPS de la stabilité à l’air de la composition chimique de surface de InP traité a révélé le caractère protecteur du film. La valeur élevée de la capacité interfaciale après traitement anodique suggère que l’interface modifiée (de type Electrolyte-Insulator-Semiconductor) est en régime d'accumulation et se comporte comme un « vrai » condensateur. / Indium phosphide (InP) is a III-V semiconductor, which represents an ideal candidate for optoelectronic applications. However, its spontaneous oxidation in air leads to the loss of its electrical properties. The surface passivation becomes a key step for its integration in attractive optoelectronic devices. As part of this thesis, we are interested in studying the passivation of the InP surface by nitridation. We reproducibly realized the formation of a polyphosphazene-like (H2N-P=NH)n film on InP by electrochemical treatment in liquid ammonia (-55°C). The monitoring of the film formation was performed using a systematic coupling between electrochemical measurements (J = f(E), J = f(t), E = f(t), and C = f(E)) and XPS analysis (X-ray photoelectron spectroscopy) to follow the chemical composition of the surface. These techniques provide some answers about the nitridation mechanism of InP surface by a wet process (anodization in NH3 liq), leading to the formation of the phosphazene film through an ECE mechanism “Electrochemical-Chemical-Electrochemical”. The study of the air ageing of the modified surface using XPS analysis revealed the protective nature of the film. The high value of the interfacial capacity after the anodic treatment suggests that the modified interface (Electrolyte-Insulator-Semiconductor-like) is in accumulation state and behaves like a "real" capacitor.