The TiCl4 mediated condensation of benzil with anilines followed by Li mediated cyclodehydrogenation of the resulting benzildiimines to access the superbulky a-dimine ligands Ll (N,N'-bis-(2,6-diisopropylphenyl)-phenanthrene-9, 1 O-diylidendiamine) and L2 (N-(2,6- diisopropylphenyl)-N'-(2,4,6-trimethylphenyl)-phenanthrene-9, 1 O-diylidenediamine) is described in this work. This route has been chosen among many other routes which failed to access these ligands. These ligands have been for the first time synthesized and fully characterized, including their single crystal X-ray structures. Attempts to tetrahedrally coordinate NiBr2 to the super bulky ligand Ll failed due to the axial crowding caused by the aryl substituents in the ortho position. Reducing this axial bulk at one side of the ligand from isopropyl groups to methyl groups as in ligand L2 enabled the synthesis of the tetrahedral NiBr2-complex (L2NiBr2). A failure has been also the attempt to coordinate MO(CO)4 to both these ligands. Instead, with the super bulky ligand Ll, a square planar Ni-allyl complex [(113- LINiC3~COOCH3)t. {B[C6H3(CF3)2k} could be easily accessed. These Ni-complexes have shown to be potent catalysts for ethylene polymerisation. The Ni-allyl version of ligand Ll has not been able to polymerize I-hexene. PdCh complexes (LIPdCh) and (L2PdCh) have been synthesized. Stirring of (LIPdCh) complex with Na B[C6H3(CF3)2]4 in acetonitrile afforded a good yield of the cationic chloroacetonitrile complex [LIPdCINCCH3t.{B[C6H3(CF3)2k}. This reaction with (L2PdCh) afforded also good yields not of the desired [L2PdCINCCH3t.{B[C6H3(CF3)2k} but of the dimer [(L2PdCI)2]2+.2{B[C6H3(CF3)2k}. This behaviour has precedent in the literature and might be due to the reduced bulk of this ligand as compared with Ll. [LIPdCINCCH3t.{B[C6H3(CF3)2]4-} has been successfully methylated with Sn(CH3)4 in DCM as solvent affording good yields of the methyl acetonitrile complex [LIPdCH3NCCH3t.{B[C6H3(CF3)2k}. The methylation of the dimer [(L2PdCI)2]2+.2{B[C6H3(CF3)2]4-} failed in DCM but was succesful in acetonitrile affording a good yield of [L2PdCH3NCCH3t.{B[C6H3(CF3)2]4-}. These palladium methyl acetonitrile complexes have been tested for ethylene, I-hexene and cyclopentene polymerization. Branched polyethylene and polyhexene with relatively high molecular weight have been produced by these catalysts. Catalyst [LIPdCH3NCCH3t.{B[C6H3(CF3)2]4-} was more active and produced higher molecular weight and less branched polymer than catalyst [L2PdCH3NCCH3t.{B[C6H3(CF3)2k } in the polymerization of ethylene. The opposite trend has been observed for I-hexene polymerization where catalyst [L2PdCH3NCCH3t.{B[C6H3(CF3)2k} was more active and produced higher molecular weight polymer than catalyst [LIPdCH3NCCH3t.{B[C6H3(CF3)2]4-}. Atactic polycyclopentene with much lower T g and T m than the ones reported in the literature for isotactic polycyclopentene, has been obtained with these catalysts. Tacticity was determined by 13CNMR.

Pulsed plasma polymerization provides a direct method for the functionalization of solid surfaces. Compared to low power continuous wave plasma conditions, it provokes very little monomer fragmentation and leads to high levels of structural retention. The monomers investigated in this thesis contained a polymerizable double bond and either a perfluoro, epoxide, cyano, hydroxyl or furan functionality. Under pulsed conditions activation of the double bond occurs during the time on period and conventional intermolecular propagation reactions occur during the time off. In the case of dienes, cyclic structures are formed, via intramolecular propagation. The plasma polymers were investigated using X-ray photoelectron, infrared, ultraviolet/visible and secondary ion mass spectroscopies, nuclear magnetic resonance, contact angle and gel permeation chromatography. Epoxide and hydroxyl functionalized solid surfaces could be further functionalized via conventional chemistry reactions. Furan functionalized solid surfaces were capable of undergoing Diels-Alder reactions. The cyano functionalized layers were found to readily complex silver ions from solution. Epoxide and cyano functionalized surfaces exhibited adhesive behavior.

Maleic anhydride (MA) is a strong electron acceptor and so homopolymerises with difficulty. Copolymerisations with electron donor monomers are however facile. Free-radical and controlled radical polymerisation (CRP) techniques have been used to probe the structure and mechanism of MA alternating copolymers. Conventional free-radical polymerisation was used to synthesise poly (octadecene -alt- MA) (PODMA). Molar masses ranging from 4,000 g morl to 61,000 g morl were successfully prepared by variation of polymerisation conditions. Molar mass characterisation was by size exclusion chromatography (SEC) and dilute solution viscometry. Calculation of monomer reactivity ratios revealed PODMA to have a strictly alternating structure. NMR analysis indicated that PODMA had 100% trans stereochemistry and the initiation and termination mechanisms were elucidated. The optimised copolymerisation was scaled up from gram to kilo scale, providing an important precursor for high performance crankcase oil dispersants. MA has proved to be a challenging monomer for CRP. Reverse addition fragmentation transfer (RAFf) copolymerisation was used to copolymerise MA with styrene (St) monomers. Kinetic studies indicated controlled copolymerisation and living characteristics were observed such as predetermined molar mass, narrow molar mass distribution and chain extension to form novel block copolymers. The RAFT mechanism and its effectiveness in producing controlled copolymers incorporating MA are discussed.

This thesis details the synthesis of highly C02-soluble hydrocarbon stabilisers using reversible addition fragmentation chain transfer (RAFT) polymerisation techniques, and their application in the dispersion polymerisation of N-vinyl pyrrolidone (NVP) in supercritical carbon dioxide (scC02). Chapter 1 outlines the key themes explored throughout the thesis. This introductory chapter focuses on the RAFT polymerisation process, the use of scC02 as an alternative solvent for polymerisation, and the process of dispersion polymerisation, including the types of stabilisers employed in such reactions. In Chapter 2, the equipment and characterisation techniques are detailed. The high pressure vessels used extensively throughout the thesis are described, including the high pressure variable volume view cell and the 60 ml clamp-sealed autoclave. Polymer characterisation techniques such as scanning electron microscopy (SEM), nuclear magnetic resonance (NMR) and gel permeation chromatography (OPC) are also considered. Chapter 3 is the first of three research chapters, and investigates the synthesis of hydrocarbon stabilisers composed of the monomers of vinyl acetate (V Ac) and vinyl pivalate (VPi) using xanthate-mediated RAFT polymerisation. The phase behaviour of a range of stabilisers in scC02 is determined through cloud point measurements using a high pressure variable volume view cell. The impact of adjustments to parameters such as polymer composition and molecular weight on CO2-solubility are considered. Chapter 4 details the application of the homopolymers and statistical copolymers of V Ac and VPi synthesised in the previous chapter. The polymers are employed as stabilisers in the dispersion polymerisation of NVP in SCC02. A range of stabilisers are considered and the resulting poly(vinyl pyrrolidone) (PNVP) products compared using NMR and SEM to gauge the effect on particle morphology. Chapter 5 describes the extension of the research to consider the impact of changes to the hydrocarbon stabiliser architecture. A series of block copolymer structures are prepared, and the phase behaviour and stabilising ability of these materials in scC02 is considered. Additionally, modification of the alpha- and omega-end of the RAFT-terminated polymers is considered through use of a different xanthate-based RAFT agent, and modification of the polymer post-polymerisation via radical-induced reduction. Chapter 6 describes the overall conclusions obtained from the work presented in the thesis, and also details possible avenues for further research in this area.

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Ces travaux de thèse présentent une étude du mécanisme de compatibilisation induit par des nanoparticules d’argile dans les mélanges de polymères en utilisant la rhéologie. Pour cela, de la montmorillonite, la laponite et l’halloysite, modifiées ou non, ont été ajoutées à des mélanges PMMA/PS. Les résultats de rhéologie linéaire en cisaillement ont montré que le mécanisme de compatibilisation, particulièrement le phénomène de coalescence, dépendait beaucoup de la localisation des nanoparticules. La montmorillonite modifiée, présente à l’interface entre les polymères, est la plus efficace à inhiber la coalescence et est aussi efficace qu’un copolymère à bloc de haute masse molaire. Ceci est particulièrement intéressant car les nanoparticules d’argile représentent un coût moindre comparé aux copolymères à bloc. Dans ces travaux, une attention spéciale a été portée aux relaxations présentes dans les mélanges. En utilisant la rhéologie linéaire en cisaillement, un effet Marangoni a été mis en évidence pour la première fois dans le cas de nanoparticules d’argile modifiées présentes à l’interface. Enfin, les mélanges soumis à un flux élongationnel puis relaxation ont montré que la relaxation des gouttes de phase dispersée après une importante déformation était plus rapide par ajout d’argiles dispersées dans la matrice et ralentie par des argiles mieux dispersées soit à l’interface, soit dans l’ensemble du mélange. / In this thesis, the compatibilization mechanism induced by clay nanoparticles in polymer blends was investigated using rheology. To do so, montmorillonite, laponite and halloysite, modified or not, were added to PMMA/PS blends. Linear shear rheology showed that the compatibilization mechanism, especially the coalescence phenomenon, was greatly influenced by the localization of clay nanoparticles. Modified montmorillonite, which was located at the interface, was shown to be the most efficient at inhibiting coalescence among clays and as efficient as a block copolymer with a high molecular mass. The latter is particularly interesting as nanoparticles are cheaper than block copolymers. In this work, special attention was given to relaxations happening in blends. Using linear shear rheology, Marangoni stresses due to a gradient in compatibilizer concentration at the interface was evidenced for the first time in the case of organically modified clay nanoparticles when located at the interface. Finally, submitting blends to elongational flow and subsequent relaxation showed that the relaxation of the droplets after high deformations was faster in the case of clays dispersed in the matrix and slowed down by the interfacial tension in the case of a better dispersion of clays at the interface or in the whole blend.

The basis for this research project is based on the discovery in the previous research that 2,2' ,5-trimethyl-3-( I-phenylethoxy)-4-tert-butyl-3-azahexane, (Styryl- TITNO) is able to control bulk polymerization of styrene at temperature as low as 70°C. The principle objective of this project was to evaluate the feasibility of using Styryl- TITNO to control radical solution and miniemulsion polymerizations at temperatures below 100°C. Styryl- TITNO was shown to effect solution polymerizations of both n-butyl acrylate (BA) and styrene below 100°C. Polymerization temperature was shown to be a crucial parameter for achieving control in Styryl- TITNO -mediated polymerizations. Good control of the number-average molecular weight (Mn) and molecular weight dispersity for the polymerization of BA was observed at 90°C. However, a lower temperature of 70 °C is required for good control of styrene polymerization. Living characteristics of polymer chains were demonstrated by a sequential chain extension of TITNO -terminated PBA with styrene at 90°C to form poly(n-butyl acrylate)- block-poly[(n-butyl acrylate)-co-styrene], [pBA-b-P(BA-co-PS)], block copolymers. An improvement in livingness in these reactions was observed when the second P(BAlstyrene) block was formed at 70°C after the first PBA block was produced at 90°C. Kinetics studies facilitated determination of the activation-deactivation equilibrium constant (K), which for styrene polymerization at 90°C (K = 4.1 x 10.9 mol L-J at 90°C and 3.0 x 10-9 mol L-J at 70 "C) is nearly an order of magnitude higher than that for BA polymerization at the same temperature (K = 8.5 x 10-11 mol L-I). This is the reason why BA polymerization shows better control than styrene polymerization at 90°C. The activation energy (Ea) for thermolysis of Stryl- TITNO is 104.1 kJ mol", which is relatively low compared to the literature values of Ea for various styryl alkoxymines. This explains why Styryl- TITNO is able to effect polymerization at temperatures as low as 70 "C. The studies of Styryl- TITNO-mediated miniemulsion polymerizations at 90 "C indicate that accumulation of free TITNO• in the particles is an issue for use of Styryl- TITNO in miniemulsion polymerizations. The use of L-ascorbic acid (L-AA) and L-ascorbic acid 6-palmitate (L-AAP) as nitroxide scavengers to reduce the level of free TITNO • in the polymerization was investigated. The best result was observed for the polymerization of BA in the presence of 5.35 mol% of L-AAP relative to Styryl- TITNO, which attained 48% conversion after 5 h. The chain extension of isolated TITNO -terminated PBA, TITNO -PBA, was used to examine the livingness of - polymer -chains before the rate of polymerization was severely retarded. The livingness of TITNO-PBA was evidenced by a shift of the staring PBA molecular weight distribution towards higher molecular weight, which provides solid evidence that the majority of polymer chains remained living. Thus, it can be concluded with certainty that the accumulation of free TITNO• was mainly responsible for the suppression of polymerization in miniemulsion polymerizations mediated by Styryl- TITNO.

Σκοπός της παρούσας διπλωματικής εργασίας είναι η σύνθεση και ο χαρακτηρισμός νανοσωματιδίων αργύρου και χρυσού με και χωρίς την παρουσία πολυμερούς. Δύο κατηγορίες νανοσωματιδίων συντέθηκαν, η πρώτη είναι νανοσωματίδια Ag και μελετήθηκε η συναρμογή τους στην κορώνα μικκυλίου συμπολυμερούς. Η δεύτερη κατηγορία είναι νανοσωματίδια χρυσού και μελετήθηκε η αλληλεπίδραση συμπολυμερούς με την επιφάνεια των νανοσωματιδίων. Η εργασία επικεντρώθηκε στη σύνθεση και την φασματοσκοπική μελέτη των νανοσωματιδίων και των υβριδικών υλικών χρησιμοποιώντας όλες τις διαθέσιμες τεχνικές δομικού χαρακτηρισμού. Αναλυτικότερα στο μεγαλύτερο μέρος της εργασίας περιγράφεται η σύνθεση νανοσωματιδίων αργύρου και η in situ σύνθεση μεταλλικών νανοσωματιδίων αργύρου στην κορώνα συμπολυμερούς. Τα νανοσωματίδια αργύρου συντέθηκαν από την αναγωγή άλατος AgNO3 και την προσθήκη ποσότητας αναγωγικού μέσου, στην συγκεκριμένη περίπτωση NaBH4. Με την προσθήκη του αναγωγικού μέσου ο άργυρος από Ag+ ανάχθηκε σε Ag0 . Νανοσωματίδια αργύρου συντέθηκαν in-situ στην κορώνα του συμπολυμερούς PHOS-PEO. Το πρωτόκολλο που ακολουθήθηκε περιλαμβάνει τα παρακάτω βήματα. Αρχικά για την διαλυτοποίηση του συμπολυμερούς επιλέχθηκε εκλεκτικός διαλύτης ως προς την μια συστάδα του, ώστε να σχηματιστούν μικκύλια αποτελούμενα από έναν συμπαγή υδρόφοβο πυρήνα και μια διαλυτή κορώνα. Στη συνέχεια προστίθεται το άλας του μετάλλου στο διάλυμα με αποτέλεσμα την συναρμογή του στην κορώνα, τέλος η αναγωγή των μεταλλικών ιόντων σε μεταλλικά νανοσωματίδια με την προσθήκη κάποιου αναγωγικού μέσου. Η δεύτερη κατηγορία αφορά την σύνθεση νανοσωματιδίων χρυσού με την μέθοδο Turkevic. Η σύνθεση έγινε με την διαλυτοποίηση σε νερό άλατος χρυσού HAuCl4 και την θέρμανση του σε στήλη με διπλό τοίχωμα στους 100⁰C και με ταυτόχρονη ανάδευση. Αφού το διάλυμα έφτασε σε σημείου βρασμού έγινε η προσθήκη του αναγωγικού μέσου και το άλας χρυσού ανάχθηκε από Au+3 σε Au0 . Τα νανοσωματίδια που παρασκευάστηκαν με την παραπάνω μέθοδο προστέθηκαν σε διάλυμα νερού με συμπολυμερές PHOS-PEO το οποίο είχε δημιουργήσει μικκύλιο λόγω του αμφίφιλου χαρακτήρα του. Και στις δύο κατηγορίες μελετήθηκε το μέγεθος το σχήμα και η σταθερότητα τους. Καθώς και έγινε σύγκριση με τα νανοσωματίδια αργύρου και χρυσού με την παρουσία πολυμερούς ως προς την σταθερότητα τους σε βάθος χρόνου. Βρέθηκε ότι υπάρχει ισχυρή αλληλεπίδραση ανάμεσα στο συμπολυμερές PHOS-PEO και στα νανοσωματίδια αργύρου που συντέθηκαν παρουσία του συμπολυμερούς, και σημειώθηκε σημαντική συμβολή του συμπολυμερούς στην ομοιογένεια και σταθερότητα των αιωρημάτων των νανοσωματιδίων σε βάθος χρόνου. Αντίθετα, η αλληλεπίδραση του ίδιου συμπολυμερούς με νανοσωματίδια χρυσού αποδείχθηκε ασθενής. / -