Dissertations / Theses on the topic 'Free radical photo polymerisation'
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Dobie, Christopher George. "A Study of Bulk Free-Radical Photo Copolymerisation and Surfactant Free Emulsion Polymerisation Using Intensified Processing Methods." Thesis, University of Newcastle Upon Tyne, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.512198.
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Shooter, Andrew James. "Living free radical polymerisation." Thesis, University of Warwick, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263817.
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Parkes, Caroline Margaret. "'Living'/Controlled free-radical polymerisation." Thesis, University of Manchester, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488186.
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Eason, Michael Douglas. "Water-soluble polymers from controlled free-radical polymerisation." Thesis, University of Warwick, 2000. http://wrap.warwick.ac.uk/36687/.
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Functional water-soluble polymers are used in the detergents industry as antidye transfer agents. Anti-dye transfer agents are materials that complex with dye in solution and therefore prevent the transfer of dye between clothing during the laundering cycle. Current commercially available anti-dye transfer agents are based on homopolymers or statistical co-polymers that contain poly(N-vinyl pyrrolidone). These polymers are covered by extensive patent protection from various companies and have also been shown to precipitate from solution at high dye concentrations. Novel free-radical polymerisation techniques have been used here to prepare controlled architecture polymers based on poly-2-(dimethylamino)ethyl methacrylate that contain hydrophilic, anionic and cationic functionality. Free-radical polymerisation has been used to prepare statistical co-polymer species that contain quaternary charge. Atom transfer polymerisation (ATP) has been used to prepare gradient co-polymers and catalytic chain transfer polymerisation has been used to prepare macromonomers as precursors to block co-polymer products. The dye-binding constants of these novel polymers have been determined using an adaptation of the static sorption technique with Direct Red 80 azo-dye in deionised water and in anionic surfactant stock solution. The data from these tests have improved reproducibility compared with previous studies and tests containing anionic surfactant have highlighted the shortcomings of the static sorption model previously used to determine the dye-binding ability of polymers with dye in deionised water. Hydrophilic gradient co-polymers that contain one dye-binding functionality and one water soluble functionality have been found to offer no significant increase in the dye-binding ability of the polymer species in comparison with the equivalent statistical co-polymer species.
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Ludlow, Andrew John. "Free radical polymerisation studies of 4-substituted styrenes." Thesis, London South Bank University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336419.
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Hart-Smith, Gene On Chemistry Faculty of Science UNSW. "Mass spectrometric investigations into free radical polymerisation reaction mechanisms." Awarded by:University of New South Wales. Chemistry, 2009. http://handle.unsw.edu.au/1959.4/44621.
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Contemporary mass spectrometry (MS) instrumentation featuring electrospray ionisation (ESI) or matrix-assisted laser desorption/ionisation (MALDI) ion sources were used to characterise the polymer distributions generated in various free radical polymerisations, allowing insights to be gained into the reaction mechanisms operating in these systems. In studying atom transfer radical polymerisation (ATRP) mediated star polymerisations of methyl acrylate (MA), ESI was found to be more effective in obtaining a comprehensive list of the distinct products present in the samples under investigation when compared to the employed MALDI technique. Furthermore, these studies showed that terminal Br losses observed at relatively high monomer to polymer conversions could be accounted for via mechanisms involving the acetone derived radicals (CH3)2??OH, ??H3 and ??H2COCH3. Through the use of ESI, it was found that for bulk polymerisations of MA and aqueous media polymerisations of N-isopropylacrylamide (NIPAAm) initiated using 60Co ??-irradiation and mediated via reversible addition-fragmentation chain transfer (RAFT), hydrogen radicals formed via the radiolysis of RAFT agent and/or monomer, and in the case of the NIPAAm system, water, are capable of initiating the polymerisations. In the NIPAAm polymerisations under scrutiny, it was also observed that hydroxyl radicals generated via the radiolysis of water may contribute towards the initiation process, and that propagating chains can potentially become terminated via trithiocarbonate cleavage reactions. By using ESI instruments to characterise oligomer samples produced via the free radical polymerisations of vinyl phosphonates, it was observed that chain propagations are initiated via activated monomer radicals, which likely form as a result of transfer reactions involving initiator fragments and vinyl phosphonate monomer units. Transfer to monomer reactions were suggested to limit chain growth in these systems, and evidence was also found for scission reactions involving alkoxy moieties which are formed via intramolecular methine carbon abstraction reactions. Characterisation of the polymer distributions generated in R-group approach RAFT MA star polymerisations using an ESI instrument allowed formation processes operating in acrylate star living/controlled radical polymerisations (CRPs) to be ascertained. Initiator fragment derived linear chains, ideal stars, star-star couples, and terminated star products formed as a result of disproportionation and combination reactions were detected. Evidence for mid-chain radical (MCR) derived reaction pathways was also observed; specifically, for termination reactions involving intermolecularly formed MCRs on both star arms and linear chains, and for re-propagation of intermolecularly formed MCRs on star arms.
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Li, Jianing. "Free radical polymerisation in supercritical carbon dioxide expanded phase." Thesis, University of Nottingham, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.576539.
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This thesis describes the conventional free radical and RAFT polymerisation in supercritical carbon dioxide (scC02) expanded phase and polymerisation of isoprene towards the synthesis of squalene. Chapter 1 gives a general introduction to the methods employed in this thesis. This chapter is consisted of two parts: polymerisation techniques and polymerisation in SCC02. Since the main technique used in this work includes reversible addition fragmentation chain transfer (RAFT), atom chain transfer polymerisation (ATRP) and catalytic chain transfer polymerisation (CCTP), a thorough description of these methods are provided. Furthermore, as SCC02 is used, its features and applications are described. Chapter 2 provides a description of the experimental process and the analytical techniques adopted in this project. The high pressure vessels are described in detail. Chapter 3 explores the free radical polymerisation (FRP) with a conventional chain transfer agent (CTA) - dodecyl mercaptan (DDM) in scC02 expanded phase. The molecular weight effect on this system is discussed. Polymerisations were conducted with various monomer/scCO2 ratios, temperatures and pressures. A range of monomers are explored, including methyl methacrylate (MMA), styrene, vinyl acetate (VAc), vinyl pivalate (VPi) and acrylic acid (AA). The morphology and appearance of the products are also discussed. This work is extended to controlled/pseudo-living radical polymerisation using RAFT as control agent. The reactions are conducted with different target molecular weights. The polymerisation kinetics and end-group functionality are examined. Finally, the thermal stability of products is compared with the DDM terminated polymers. Chapter 5 describes the synthesis of poly(isoprene) (PI) to replace squalene/squalane for cosmetic applications. The reactions are conducted in both conventional solvents and scC02 expanded phase. Different polymerisation techniques are used, including CCTP, RAFT, ATRP and RATRP. The CCTP process is successfully scaled up and the products are hydrogenated to yield squalane for application tests. Chapter 6 summarises the research presented in this thesis and overall conclusions are provided.
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Arsu, Nergis. "Some aspects of free radical polymerisation in UV-curing." Thesis, City University London, 1993. http://openaccess.city.ac.uk/8266/.
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Various quinoxalines, in association with N-methyld-iethanolamine as synergist, were used to initiate the polymerisation of acrylates. It was found that the quinoxalines where used with amine synergist are efficient Type II initiators. It was also found that the cure of the acrylate is faster when oxygen is present in the reaction mixture than when it is absent. The photoinitiating efficiency of 2-Methyl-1-[4-(methylthio)phenyl]-2- morpholinopropane-1-one (IRG-907) was compared to different initiators using RTIR spectroscopy and N-Isopropylmorpholine(IPM) was used as a model to investigate the properties of the morpholino sustit.uent present in IRG-907. It was shown by RTIR spectroscopy, photocalorimetry,bulk polymerisation and the curing of thin films that 1PM acts as a physical quencher for the triplet state of IRG-907 and that it is a very poor hydrogen donor. Sensitisation of IRG-907 by lix was also investigated and it wasconfirmed that lix can sensitise the cleavage of 1RG907. Photoinduced fragmentation of aminoalcohols by quinoxalines are discussed and the reactivity of the aminoalcohols reflect their ability to undergo electron transfer and to fragment. A wide range of aminoalcohols were synthesised and used as synergist in the polymerisation of a number of acrylates using different methods and the photoyellowing and photooxidation of aminoalcohols were also investigated. Some mixed acrylate-cinnamate systems were prepared to investigate a new dual cure system. The conversion percentage was found to be very low. The lack of cure is probably due to the cinnamates are scavenging the benzoyl radicals.
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Pullen, Graeme K. "2-substituted anthraquinones as photoinitiators of free radical polymerisation." Thesis, Manchester Metropolitan University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320492.
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Fraser, Kathryn. "An investigation of nitroxide-mediated polymerisation." Thesis, University of York, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288036.
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Kurinczuk, Andrew H. "The kinetics of free radical bulk polymerisation at high conversion." Thesis, Loughborough University, 1991. https://dspace.lboro.ac.uk/2134/7117.
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An investigation was carried out to discover the effects of high conversion on the kinetic rate coefficients for the polymerisation of styrene. In such regimes, the reaction medium is of such high viscosity that these coefficients (kp and kt) exhibit profound changes. The changes were investigated with respect to the viscosity of and volume fraction of polymer present in the reaction medium. To circumvent the need to polymerise the monomer from the zero conversion, pre-formed polystyrene of known molecular weight was dissolved in purified styrene monomer. The resulting viscous solutions were then polymerised with AIBN as initiator. Effects on kp, kt and a reduction in f, initiator efficiency, were noted. Volume-fraction based models of termination kinetics were shown to be less applicable than one based on viscosity.
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Dieudonne, Lucile. "Synthesis, characterisation and cytotoxicity evaluation of novel polymeric carriers for polymer therapeutics : from free radical polymerisation to atom transfer radical polymerisation." Thesis, Cardiff University, 2008. http://orca.cf.ac.uk/55722/.
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Polymer therapeutics include water-soluble polymers designed as carriers for drugs, proteins or DNA. Over the last two decades, they have found increasing clinical use against cancer and other diseases. A growing number is in clinical trials or on the market. However, the polymers used so far have limitations including heterogeneity in structure, molecular weight, polydispersity, drug carrying capacity, lack of control of architecture and biodegradability of polymer backbone. Therefore, the aim of this study was to synthesise and characterise a library of linear/star homo/copolymers with potential for further development as second-generation polymer therapeutics. Atom Transfer Radical Polymerisation (ATRP) and (chain transfer agent - CTA) Free Radical Polymerisation (FRP) techniques were used to synthesise water-soluble amine-based acrylamide and methacrylate homo/copolymers. Nuclear magnetic resonance, gel permeation chromatography, infrared and titration were used for characterisation. In vitro cytotoxicity studies of the polymers towards a murine melanoma cell line were performed using a cell viability evaluating colorimetric assay. Molecular weights (from 3,000 to 550,000 g.mol --1) were successfully adjusted by varying either the initiator or CTA to monomer ratios. Semitelechelic homo/copolymers with either carboxylic acid or hydroxyl termini were obtained using mercapto-based CTA. Either stable or degradable star-shaped poly(dimethylaminoethyl methacrylate) were obtained by copper-mediated ATRP using previously synthesised multifunctional initiators (4, 5 or 8 initiating moieties). A linear increase of predictable molecular weight with monomer conversion and narrow polydispersity (1.3) were observed. Amongst other molecular parameters systematically tested, the amount of cationic residues had the most striking effect on the cell viability. To conclude, conditions were optimised for the synthesis of a library of water- soluble amine-based homo/copolymers with different molecular weight, composition, charge density and architecture using several polymerisation techniques. Preliminary evaluation of polymer cytotoxicity associated to molecular parameters is vital for intelligently designing future, novel, and biocompatible polymeric carriers.
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Tat, Nguyen Cam. "A novel free radical polymerisation approach to hyperbranched poly(methyl methacrylate)." Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417994.
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Mortamet, Anne-Cecile. "Redox free radical polymerisation of 4-methylstyrene : thermal and spectroscopic characterisations." Thesis, University of Strathclyde, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.502357.
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Free radical polymerisation of vinyl monomers has been widely used over the years in industry to prepare high molecular weight polymers. More recently, reactions involving transition metal catalysts have been investigated in order to operate under milder conditions and enhance the physical and mechanical properties of the final material. In this report, we present the free radical redox polymerisation of 4-methylstyrene used in the manufacture of glass-reinforced plastic. The reaction is thermally initiated and also catalysed by a cobalt complex and a tertiary amine.
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Tai, Hongyun. "Free radical heterogeneous polymerisation of vinylidene fluoride in supercritical carbon dioxide." Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428931.
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Mouillat, Claire G. J. "Application of UV curing to the preparation of composite materials." Thesis, University of Kent, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360968.
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McAllister, Thomas D. "Expanding the scope of free-radical dispersion polymerisation in supercritical carbon dioxide." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/46744/.
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Electrophoretic displays (EPD) show several advantages over other display screen types including being easy on the eye, low power consumption, good visibility in bright daylight and a wide viewing angle. However, conventional EPDs only offer black and white images. One possible approach to colour EPD is the use of coloured particles. Here, the colours that can be displayed are dictated largely by the colour of the colloidal particles dispersed within the screen, which are traditionally carbon black and titanium dioxide white. In this thesis, dispersion polymerisation of methyl methacrylate (MMA) in supercritical carbon dioxide (scCO2) is investigated as a simple route to producing functional particles for application in colour EPDs. First, using a commercially available poly(dimethyl siloxane) PDMS based stabiliser, multi-stage injections are used in order to allow greater particle size control than previously published for any single stabiliser, producing particles between 309 and 3966 nm in diameter. Particle size distributions (PDI) of ~1.5 were consistently obtained for particles synthesised using this process. The method was then adapted in order to allow the incorporation of acid and base functionalised monomers in order to aid particle charging as well as acrylic dyes for colour. Analysis of these particles revealed that various core-shell structures were achieved and could be influenced by solvent and monomer choice. Finally, dyed particles synthesised using the techniques developed during this project were assessed for their ability to function in EPDs. Colour switching was successful and synthesis in scCO2 was shown to yield better separation of the white and coloured states of the test cells than those produced by analogous synthesis in conventional media.
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Adash, Uma. "Synthetic and kinetic investigations into living free-radical polymerisation used in the preparation of polymer therapeutics." Thesis, University of Canterbury. Chemistry, 2006. http://hdl.handle.net/10092/1282.
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The aim of this work was to successfully prepare polymers of N-(2-hydroxypropyl)methacrylamide, (PHPMA) using controlled/"living" free-radical polymerisation technique. For this purpose, atom transfer radical polymerisation (ATRP) and reversible addition-fragmentation (chain) transfer (RAFT) polymerisation were used in preparation of a number of base polymers with the intention of quantitatively converting them into PHPMA. Both methods were applied under varying polymerisation conditions, and the kinetics of the systems investigated. Various rate constants were measured, while computer modelling of the experimental data allowed estimation of other kinetic parameters of interest. Investigations into solvent and ligand effects on the kinetics of ATRP of the activated ester methacryloyloxy succinimide (MAOS) and one of the archetypal methacrylate monomers, methyl methacrylate (MMA) were carried out. The method of RAFT was also employed in polymerisation of MAOS and a number of other monomers in the hope of finding the best synthetic precursor of PHPMA. Polymers of methacryloyl chloride (MAC) and p-nitrophenyl methacrylate (NPMA) were prepared, as well as the polymers of HPMA itself and N-isopropyl methacrylamide. Polymerisation of MMA by RAFT was also attempted in view of adding to current knowledge on the monomer's behaviour and the kinetic characteristics of its RAFT polymerisation. Preparation of PHPMA from PMAOS, PMAC and PNPMA was attempted. Successful preparation of PHPMA from the polymer of the acid chloride was achieved under mild reaction conditions, while displacement of N-hydroxysuccinimide groups of PMAOS resulted in unexpected modification of the polymer under the conditions used. Conversion of PNPMA into PHPMA was not achieved. At this stage these results suggest inadequacy of both PMAOS and PNPMA as reactive polymeric precursors.
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Birchall, Andrew Carl. "The synthesis of novel homochiral polymers from amino acids." Thesis, Bangor University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310924.
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Bradley, Grant. "Hexaarylbisimidazoles as initiators of acrylate polymerisation : some new synthesis and application." Thesis, University of Kent, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360967.
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Chaffey-Millar, Hugh William Chemical Sciences & Engineering Faculty of Engineering UNSW. "An experimental and computational study of two state of the art living free radical polymerisation techniques." Awarded by:University of New South Wales. Chemical Sciences & Engineering, 2008. http://handle.unsw.edu.au/1959.4/41421.
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This thesis describes the research conducted by t he author in completion of a Doctor of Philosophy in the Centre for Advanced Macromolecular Design(CAMD), Univcrsity of New South Wales (UNSW) , Sydney, Australia; under the supervision of Professor Christopher Barner-Kowollik and Doctor Michelle L. Coote (Australian National University). The research has led to the creation of new knowledge in the fields of free radical polymerisation and chemical kinetics. Research was conducted in two main thrusts: (1) investigation into the governing kinetic processes behind star polymer synthesis via what has become known as a reversible addition fragmentation chain transfer (RAFT), R-group approach and (2) an entirely new mode of living free radical (LFR) polymerisation which has been named thioketone mediated polymerisation (TKMP). In the first broad area of the described research, a novel kinetic modelling scheme has been developed in which only the reactions of a single arm star are simulated explicitly. Subsequently, the molecular weight distributions (MWDs) arising from the single arm star simulation are convolved, using probabilistic calculations, to generate the MWD appropriate to a multi-arm star polymerisat ion bearing t he same kinetic parameters as the single arm one. This model is validated against experimental data, enabling, for the first time, the use of rigorous theoretical reasoning to distill a set of synthetic guidelines for star polymer synthesis via a RAFT, R-group approach. Subsequently, the product spectra resulting from RAFT, R-group approach polymerisations of para-acetoxystyrene have been analysed via mass spectrometry. This has led to direct evidence for many of the complex species whose existence had, up until this point, been inferred from gel permeation chromatography (GPC) measured MWDs. The menagerie of species identified includes, but is not limited to, star-star couples, initiator fragment terminated stars, initiator fragment terminated star-star couples and linear chains -- both living and terminated. Using a kinetic model devised specifically for application in mass spectrometry analysis, the experimentally observed abundances of each of the above species have been compared to t hose predicted by simulation. The qualitative agreement between the predicted and observed abundances has provided additional evidence that t he proposed mechanism for RAFT, R-group approach polymerisations is correct and operative. Further, it seems unlikely that significant, undiscovered kinetic phenomena exist. Due to (a) long simulation times encountered using the state of the art, commercial partial differential equation solver for polymerisation kinetics (i.e. PREDICI, Computing in Technology (CiT), GmbH; see http://www.cit-wulkow.de) and (b) the limited flexibility this software provides with respect to the types of chemical species that can be simulated, fundamental research has been conducted into the kinetic Monte Carlo method to (i) examine fundamental aspects of this simulation approach; (ii) determine the maximum speed attainable through a combination of optimisations including run-time generation of problem specific code and parallelisation; and, therefore (iii) find out what the potential of this method may be as a replacement for t he existing methods. In terms of speed, the developed code outperforms previous Monte Carlo benchmarks in the literature by a factor of 2.6 and the latest developments in the commercial tool, PREDICI that took place during the author's Ph.D. candidature give it similar performance to the herein described Monte Carlo code; however, the latter is required to run on multiple processors in order to compete with the serial algorithm implemented in PREDICI. The Monte Carlo method does, however, provide complete freedom with respect to the chemical species whose kinetics can be simulated, allowing for complex species with many chain lengths and, in principal copolymer compositions and branched structures. The Monte Carlo approach is the method of choice for these types of simulations and for the first time competes with the commercial tool in terms of speed. In the second broad area of the described research, an experimental investigation has been conducted into the applicability of thioketones, S=C (R1) (R2), as mediating agents for free radical polymerisations. The compound di-tert-butyl thioketone (DTBT), S=C-(C(CH3)3)2, has been chosen as a model reagent and this, when incorporated into a free radical polymerisation of styrene has led to a linear increase of the average molecular weight as conversion of monomer into polymer takes place - demonstrating control. A reversible radical trapping mechanism has been proposed and evidence for this has been provided in the form of an ab initio calculation of the equilibrium constant for the trapping of a styryl dimer radical by DTBT. This equilibrium constant was approximately K = 105 L mol-1 and is close to the value which is expected on the basis of the experimental results. To aid future experimental investigations intoTKMP, a quantum chemical survey has, been conducted with the aim of discovering the radical affinities of a large range of thioketones. It has been demonstrated that there is ample scope within this class of compound for potent radical trapping - far above that of DTBT. The affinities of various thioketone substrates for radicals have been understood in terms of the radical stabilising and thioketone destabilising effect of the two substituents R1 and R2 on, respectively, the adduct radical, R-S-C???(R1) (R2), and the parent thioketone. All results appearing in this thesis have been published previously in peer-reviewed scientific journals.
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Lussini, Vanessa C. "The synthesis and evaluation of polyaromatic profluorescent nitroxide probes for the detection of photo-oxidative polymer degradation." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/127299/1/Vanessa_Lussini_Thesis.pdf.
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This study focused on the synthesis and evaluation of novel photo-stable profluorescent nitroxide probes. The stability and performance of the newly synthesised probes were assessed under harsh environmental environments and compared with previously synthesised PFN probes. Analysis of their physical characteristics revealed that the nitroxide-fluorophore probes displayed strongly suppressed fluorescence in comparison to their corresponding non-radical derivatives. Evaluation of these probes confirmed their enhanced ability to detect radical polymer degradation in the laboratory and in true weathering conditions over any previously synthesized profluorescent nitroxides or other laboratory techniques.
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England, Richard Mark. "Free Radical Polymerisation of Linear and Highly Branched Polymers Using Reversible Addition Fragmentation chain-Transfer and an Alkylation Reaction with a Silyl Enol Ether." Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.522023.
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Vidyasagar, Ajay Kumar. "Volume Phase Transitions in Surface-Tethered, Photo-Cross-Linked Poly(N-isopropylacrylamide) Networks." Scholar Commons, 2010. https://scholarcommons.usf.edu/etd/1798.
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The overall thrust of this dissertation is to gain a comprehensive understanding over the factors that govern the performance and behavior of ultra-thin, cross-linked polymer films. Poly(NIPAAm) was used as a model polymer to study volume phase transition in surface tethered networks.
Poly(NIPAAm) undergoes a reversible phase transition at approximately 32°C between a swollen hydrophilic random coil to a collapsed hydrophobic globule state, thought to be caused by increased hydrophobic attractions between the isopropyl groups at elevated temperatures. We present a simple photochemical technique for fabricating structured polymer networks, enabling the construction of responsive surfaces with unique properties. The approach is based on the photo-cross-linking of copolymers synthesized from N-isopropylacrylamide and methacroyloxybenzophenone (MaBP). In order correlate layer swelling to the MaBP content, we have studied the swelling behavior of such layers in contact with aqueous solutions with neutron reflection.
The cross-linked networks provide a three-dimensional scaffold to host a variety of functionalities. These networks serve as a platform which can be used to amplify small local perturbations induced by various stimuli like temperature, pH, solvent, ionic strength and peptide modified hydrogels to bring about a macroscopic change. Neutron reflection experiments have shown that the volume-phase transition of a surface-tethered, cross-linked poly(NIPAAm) network coincided with the two-phase region of uncross-linked poly(NIPAAm) in solution. Parallel measurements with ATR-FTIR investigating the effect of temperature, pH and salts suggest that the discontinuous transition is the result of cooperative dehydration of the isopropyl groups, with water remaining confined between amide groups in the collapsed state as weakly hydrogen bonded bridges. Hybrid polymers with specific peptide sequences have shown specific response to external cues such as pH and metal ions exhibiting unique phase behavior.
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Blinco, James Peter. "The synthesis and application of novel profluorescent nitroxides as probes for polymer degradation." Queensland University of Technology, 2008. http://eprints.qut.edu.au/26376/.
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This PhD project has expanded the knowledge in the area of profluorescent nitroxides with regard to the synthesis and characterisations of novel profluorescent nitroxide probes as well as physical characterisation of the probe molecules in various polymer/physical environments. The synthesis of the first example of an azaphenalene-based fused aromatic nitroxide TMAO, [1,1,3,3-tetramethyl-2,3-dihydro-2-azaphenalen-2-yloxyl, was described. This novel nitroxide possesses some of the structural rigidity of the isoindoline class of nitroxides, as well as some properties akin to TEMPO nitroxides. Additionally, the integral aromatic ring imparts fluorescence that is switched on by radical scavenging reactions of the nitroxide, which makes it a sensitive probe for polymer degradation. In addition to the parent TMAO, 5 other azaphenalene derivatives were successfully synthesised. This new class of nitroxide was expected to have interesting redox properties when the structure was investigated by high-level ab initio molecular orbitals theory. This was expected to have implications with biological relevance as the calculated redox potentials for the azaphenalene ring class would make them potent antioxidant compounds. The redox potentials of 25 cyclic nitroxides from four different structural classes (pyrroline, piperidine, isoindoline and azaphenalene) were determined by cyclic voltammetry in acetonitrile. It was shown that potentials related to the one electron processes of the nitroxide were influenced by the type of ring system, ring substituents or groups surrounding the moiety. Favourable comparisons were found between theoretical and experimental potentials for pyrroline, piperidine and isoindoline ring classes. Substitution of these ring classes, were correctly calculated to have a small yet predictable effect on the potentials. The redox potentials of the azaphenalene ring class were underestimated by the calculations in all cases by at least a factor of two. This is believed to be due to another process influencing the redox potentials of the azaphenalene ring class which is not taken into account by the theoretical model. It was also possible to demonstrate the use of both azaphenalene and isoindoline nitroxides as additives for monitoring radical mediated damage that occurs in polypropylene as well as in more commercially relevant polyester resins. Polymer sample doped with nitroxide were exposed to both thermo-and photo-oxidative conditions with all nitroxides showing a protective effect. It was found that isoindoline nitroxides were able to indicate radical formation in polypropylene aged at elevated temperatures via fluorescence build-up. The azaphenalene nitroxide TMAO showed no such build-up of fluorescence. This was believed to be due to the more labile bond between the nitroxide and macromolecule and the protection may occur through a classical Denisov cycle, as is expected for commercially available HAS units. Finally, A new profluorescent dinitroxide, BTMIOA (9,10-bis(1,1,3,3- tetramethylisoindolin-2-yloxyl-5-yl)anthracene), was synthesised and shown to be a powerful probe for detecting changes during the initial stages of thermo-oxidative degradation of polypropylene. This probe, which contains a 9,10-diphenylanthracene core linked to two nitroxides, possesses strongly suppressed fluorescence due to quenching by the two nitroxide groups. This molecule also showed the greatest protective effect on thermo-oxidativly aged polypropylene. Most importantly, BTMIOA was found to be a valuable tool for imaging and mapping free-radical generation in polypropylene using fluorescence microscopy.
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Blinco, James P. "The synthesis and application of novel profluorescent nitroxides as probes for polymer degradation." Thesis, Queensland University of Technology, 2008. https://eprints.qut.edu.au/26376/1/James_Blinco_Thesis.pdf.
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This PhD project has expanded the knowledge in the area of profluorescent nitroxides with regard to the synthesis and characterisations of novel profluorescent nitroxide probes as well as physical characterisation of the probe molecules in various polymer/physical environments. The synthesis of the first example of an azaphenalene-based fused aromatic nitroxide TMAO, [1,1,3,3-tetramethyl-2,3-dihydro-2-azaphenalen-2-yloxyl, was described. This novel nitroxide possesses some of the structural rigidity of the isoindoline class of nitroxides, as well as some properties akin to TEMPO nitroxides. Additionally, the integral aromatic ring imparts fluorescence that is switched on by radical scavenging reactions of the nitroxide, which makes it a sensitive probe for polymer degradation. In addition to the parent TMAO, 5 other azaphenalene derivatives were successfully synthesised. This new class of nitroxide was expected to have interesting redox properties when the structure was investigated by high-level ab initio molecular orbitals theory. This was expected to have implications with biological relevance as the calculated redox potentials for the azaphenalene ring class would make them potent antioxidant compounds. The redox potentials of 25 cyclic nitroxides from four different structural classes (pyrroline, piperidine, isoindoline and azaphenalene) were determined by cyclic voltammetry in acetonitrile. It was shown that potentials related to the one electron processes of the nitroxide were influenced by the type of ring system, ring substituents or groups surrounding the moiety. Favourable comparisons were found between theoretical and experimental potentials for pyrroline, piperidine and isoindoline ring classes. Substitution of these ring classes, were correctly calculated to have a small yet predictable effect on the potentials. The redox potentials of the azaphenalene ring class were underestimated by the calculations in all cases by at least a factor of two. This is believed to be due to another process influencing the redox potentials of the azaphenalene ring class which is not taken into account by the theoretical model. It was also possible to demonstrate the use of both azaphenalene and isoindoline nitroxides as additives for monitoring radical mediated damage that occurs in polypropylene as well as in more commercially relevant polyester resins. Polymer sample doped with nitroxide were exposed to both thermo-and photo-oxidative conditions with all nitroxides showing a protective effect. It was found that isoindoline nitroxides were able to indicate radical formation in polypropylene aged at elevated temperatures via fluorescence build-up. The azaphenalene nitroxide TMAO showed no such build-up of fluorescence. This was believed to be due to the more labile bond between the nitroxide and macromolecule and the protection may occur through a classical Denisov cycle, as is expected for commercially available HAS units. Finally, A new profluorescent dinitroxide, BTMIOA (9,10-bis(1,1,3,3- tetramethylisoindolin-2-yloxyl-5-yl)anthracene), was synthesised and shown to be a powerful probe for detecting changes during the initial stages of thermo-oxidative degradation of polypropylene. This probe, which contains a 9,10-diphenylanthracene core linked to two nitroxides, possesses strongly suppressed fluorescence due to quenching by the two nitroxide groups. This molecule also showed the greatest protective effect on thermo-oxidativly aged polypropylene. Most importantly, BTMIOA was found to be a valuable tool for imaging and mapping free-radical generation in polypropylene using fluorescence microscopy.
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TAUFER, MICHEL. "Polymerisation et caracterisations de materiaux de coeur pour fibres optiques transparentes et scintillantes." Toulouse 3, 1989. http://www.theses.fr/1989TOU30031.
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Preparation et caracterisation de polymeres entrant dans la fabrication de fibres optiques; ameliorations du procede de fabrication de la fibre pour pallier les fluctuations de diametre. Presentation des phenomenes de luminescence et des theories existantes dans le domaine de la scintillation; justifications du choix de polystyrene ou de polymethylstyrene pour les fibres scintillantes; probleme des fibres scintillantes de faible diametre; presentation d'une methode de preparation de materiau de coeur et mesures de transparence
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Roth, Jan. "Funktionalisierung von Silikonoberflächen." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1234268177738-70409.
Full textAbstract:
Poly(dimethylsiloxan) (PDMS) ist ein wichtiges Polymer, das zunehmend in der Mikroelektronik aufgrund seiner hervorragenden Elastizität und thermischen Stabilität Verwendung findet. Ein limitierender Faktor für den Einsatz von PDMS ist aufgrund des Fehlens von reaktiven Gruppen und der niedrigen freien Oberflächenenergie seine geringe Adhäsion zu anderen Materialien. Zur Erhöhung der Adhäsion ist deshalb die Einführung von polaren, funktionellen Gruppen notwendig. Hier lag die Motivation der vorliegenden Arbeit, die sich eine gezielte Funktionalisierung von PDMS-Oberflächen als Aufgabe gesetzt hatte. Im ersten Teil der Arbeit wurde eine Verbesserung der Adhäsion zu einem fotostrukturierbaren Epoxidharz mittels der Sauerstoff- und Ammoniakplasmabehandlung angestrebt. In beiden Fällen führte die Plasmabehandlung zu der Einführung von unterschiedlichsten funktionellen Gruppen auf die Oberfläche und zu einer Verbesserung des Benetzungsverhaltens gegenüber Wasser. Zudem wurden Haftfestigkeiten erzielt, die um ein Vielfaches höher waren als jene zwischen Epoxidharz und einer unbehandelten PDMS-Oberfläche. Jedoch waren die hydrophilen Eigenschaften nach der Plasmabehandlung während der Lagerung an Luft zeitlich begrenzt, die PDMS-Oberfläche kehrt innerhalb kurzer Zeit in den einst hydrophoben Ausgangszustand zurück. Der Alterungsvorgang wird als „Hydrophobic Recovery“ bezeichnet und ist bei PDMS-Oberflächen, die höheren Plasmaleistungen und Behandlungszeiten ausgesetzt wurden, besonders auffällig. Die Vermeidung dieser Problematik war der Ausgangspunkt für den zweiten Teil der Arbeit. Auf der Grundlage der über die Plasmabehandlungen erzeugten funktionellen Gruppen wurden neue Konzepte für eine kovalente Anbindung von verschiedenen funktionellen Homo- und Copolymeren über die „Grafting to“-Technik entwickelt. Neben der Erhöhung der Adhäsion zu dem Epoxidharz war es möglich, das Benetzungsverhalten gegenüber Wasser durch die Unterbindung der „Hydrophobic Recovery“ zu stabilisieren. Des Weiteren gelang es, durch die Wahl der funktionellen Polymere, die PDMS-Oberfläche gezielt mit gewünschten Eigenschaften auszustatten. Somit ist der Einsatz der polymermodifizierten Oberflächen, außer in der Mikroelektronik, auch auf andere Anwendungen, wie der Biomedizin, der Mikrofluidik oder der Softlithografie übertragbar, in denen eine beständige, definierte Oberflächenfunktionalisierung ein wichtiges Kriterium darstellt.
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Roth, Jan. "Funktionalisierung von Silikonoberflächen." Doctoral thesis, Technische Universität Dresden, 2008. https://tud.qucosa.de/id/qucosa%3A23701.
Full textAbstract:
Poly(dimethylsiloxan) (PDMS) ist ein wichtiges Polymer, das zunehmend in der Mikroelektronik aufgrund seiner hervorragenden Elastizität und thermischen Stabilität Verwendung findet. Ein limitierender Faktor für den Einsatz von PDMS ist aufgrund des Fehlens von reaktiven Gruppen und der niedrigen freien Oberflächenenergie seine geringe Adhäsion zu anderen Materialien. Zur Erhöhung der Adhäsion ist deshalb die Einführung von polaren, funktionellen Gruppen notwendig. Hier lag die Motivation der vorliegenden Arbeit, die sich eine gezielte Funktionalisierung von PDMS-Oberflächen als Aufgabe gesetzt hatte. Im ersten Teil der Arbeit wurde eine Verbesserung der Adhäsion zu einem fotostrukturierbaren Epoxidharz mittels der Sauerstoff- und Ammoniakplasmabehandlung angestrebt. In beiden Fällen führte die Plasmabehandlung zu der Einführung von unterschiedlichsten funktionellen Gruppen auf die Oberfläche und zu einer Verbesserung des Benetzungsverhaltens gegenüber Wasser. Zudem wurden Haftfestigkeiten erzielt, die um ein Vielfaches höher waren als jene zwischen Epoxidharz und einer unbehandelten PDMS-Oberfläche. Jedoch waren die hydrophilen Eigenschaften nach der Plasmabehandlung während der Lagerung an Luft zeitlich begrenzt, die PDMS-Oberfläche kehrt innerhalb kurzer Zeit in den einst hydrophoben Ausgangszustand zurück. Der Alterungsvorgang wird als „Hydrophobic Recovery“ bezeichnet und ist bei PDMS-Oberflächen, die höheren Plasmaleistungen und Behandlungszeiten ausgesetzt wurden, besonders auffällig. Die Vermeidung dieser Problematik war der Ausgangspunkt für den zweiten Teil der Arbeit. Auf der Grundlage der über die Plasmabehandlungen erzeugten funktionellen Gruppen wurden neue Konzepte für eine kovalente Anbindung von verschiedenen funktionellen Homo- und Copolymeren über die „Grafting to“-Technik entwickelt. Neben der Erhöhung der Adhäsion zu dem Epoxidharz war es möglich, das Benetzungsverhalten gegenüber Wasser durch die Unterbindung der „Hydrophobic Recovery“ zu stabilisieren. Des Weiteren gelang es, durch die Wahl der funktionellen Polymere, die PDMS-Oberfläche gezielt mit gewünschten Eigenschaften auszustatten. Somit ist der Einsatz der polymermodifizierten Oberflächen, außer in der Mikroelektronik, auch auf andere Anwendungen, wie der Biomedizin, der Mikrofluidik oder der Softlithografie übertragbar, in denen eine beständige, definierte Oberflächenfunktionalisierung ein wichtiges Kriterium darstellt.
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Prandato, Emeline. "Relations structure-propriétés et résistance à l’endommagement de vernis acrylate photo-polymérisables pour substrats thermoplastiques : évaluation de monomères bio-sourcés et de nano-charges." Thesis, Lyon, INSA, 2013. http://www.theses.fr/2013ISAL0103/document.
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L’objectif de ces travaux a été de développer des vernis acrylate photo-polymérisables à 100% d’extrait sec, destinés à protéger des pièces thermoplastiques en polycarbonate contre les endommagements mécaniques, en particulier contre la rayure. Les relations entre la composition, la structure et les propriétés de ces revêtements ont été explorées. Pour ce faire ont été étudiées la morphologie, les propriétés thermomécaniques ainsi que la résistance à la rayure des matériaux. Cette dernière a été évaluée par des tests de micro-scratch. La cinétique de formation des réseaux polymères a elle aussi été étudiée, par photo-DSC. Tous les matériaux étudiés présentent, en analyse thermomécanique dynamique, un module élevé à l’état caoutchoutique ainsi qu’une large relaxation mécanique. Un vernis pétro-sourcé à 100% d’extrait sec, qualifié de standard, a servi de point de départ à ces travaux. Il a tout d’abord été comparé à un vernis commercial solvanté photo-polymérisable, spécialement conçu pour la protection de pièces thermoplastiques. Celui-ci s’est avéré être plus efficace en termes de résistance à la rayure. Dans un deuxième temps, a été étudiée l’influence sur les propriétés du vernis standard pétro-sourcé d’un monomère multicyclique entrant dans sa composition. La modification de son pourcentage n’a permis d’apporter aucun bénéfice en termes de résistance à la rayure. Des nanoparticules de silice, d’alumine ou de zircone, disponibles sous forme de dispersion dans un monomère acrylate, ont ensuite été incorporées dans le vernis standard pétro-sourcé. Une organisation particulière de la nano-silice et de la nano-alumine au sein des matériaux étudiés a pu être observée par microscopie électronique en transmission. Il a été constaté que le taux de charge doit être élevé pour observer une augmentation du module élastique et une amélioration de la résistance à la rayure du vernis (≥15% massique dans le cas de la nano-silice). Par ailleurs, l’ajout de 5% massique de nano-silice dans le vernis n’a conduit à aucune modification de sa cinétique de photo-polymérisation. Enfin, une partie des composés acrylate pétro-sourcés du vernis standard a été substituée par des acrylates bio-sourcés disponibles industriellement. La cinétique de photo-polymérisation des deux types de vernis est similaire. Les conclusions de la comparaison entre les vernis bio-sourcés et le vernis standard pétro-sourcé en termes de résistance à la rayure dépendent de l’épaisseur des revêtements étudiés. L’ajout d’un composé monoacrylate bio-sourcé à la formulation des vernis tend à améliorer la recouvrance élastique des revêtements de faible épaisseur. L’acrylate d’isobornyle est en particulier intéressant, car il a aussi tendance à retarder l’apparition des craquelures au cours de la rayureThe aim of this work was to develop 100% solids photo-polymerizable acrylate coatings, intended to protect thermoplastic pieces made of polycarbonate against mechanical damage, in particular scratches. The relationships between the composition, the structure and the properties of these coatings were examined. For this purpose the morphology, the thermomechanical properties and the scratch resistance of the materials, assessed by micro-scratch tests, were studied. The kinetics of the polymer network formation was also studied by photo-DSC experiments. All the materials feature a high elastic modulus and a broad mechanical relaxation in dynamic thermomechanical analysis. A 100% solids petro-based coating (standard) constituted the starting point of this work. First it was compared to a commercial photo-polymerizable coating containing solvents, specially designed to protect thermoplastic pieces. This commercial coating turned out to be more efficient against scratches. In a second time was studied the influence of the percentage of a multicyclic monomer, taking part in the composition of the standard petro-based coating, on the properties of the latter. The modification of its proportion does not bring any advantage concerning the scratch resistance. Silica, alumina and zirconia nanoparticles, dispersed in an acrylate monomer, were then incorporated in the standard petro-based coating. A particular organization of the silica or alumina nanoparticles in the materials could be observed by transmission electron microscopy. A high filler content is required to observe an increase in the elastic modulus and an enhancement of the scratch resistance of the coating (≥15% by weight for the nano-silica). Moreover, no change of the photo-polymerization kinetics was noticed through the addition of 5% by weight of nano-silica in the coating. Finally, some of the petro-based acrylate compounds of the standard coating were substituted by commercially available bio-based acrylate monomers. Both types of coatings feature similar polymerization kinetics. The conclusions concerning the comparison of the scratch resistance of the bio-based and standard petro-based coatings depend on their thickness. The incorporation of a bio-based monoacrylate compound in low thickness coatings tends to improve the elastic recovery. Isobornyl acrylate is particularly interesting since it also tends to delay the apparition of cracks along the scratch
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Mansri, Ali. "Synthese et etude de polymeres styreniques porteurs de chaines laterales polycetoniques." Le Mans, 1987. http://www.theses.fr/1987LEMA1025.
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Synthese de nouveaux polymeres styreniques portant en chaine laterale soit des motifs dicetoniques-1,5, soit des motifs di et tricetoniques-1,3. Synthese des monomeres par photoaddition d'acylindanedione ou de tricetone-1,3 sur le styrene et le paradivinylbenzene. Polymerisation et copolymerisation radicalaire des monomeres. Etude physicochimique des polymeres
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Sun, L., Anaïs Pitto-Barry, A. W. Thomas, M. Inam, K. E. B. Doncom, A. P. Dove, and R. K. O'Reilly. "Core functionalization of semi-crystalline polymeric cylindrical nanoparticles using photo-initiated thiol–ene radical reactions." 2016. http://hdl.handle.net/10454/15390.
Full textAbstract:
yesSequential ring-opening and reversible addition–fragmentation chain transfer (RAFT) polymerization was used to form a triblock copolymer of tetrahydropyran acrylate (THPA), 5-methyl-5-allyloxycarbonyl-1,3-dioxan-2-one (MAC) and L-lactide. Concurrent deprotection of the THPA block and crystallization-driven self-assembly (CDSA) was undertaken and allowed for the formation of cylindrical micelles bearing allyl handles in a short outer core segment. These handles were further functionalized by different thiols using photo-initiated thiol–ene radical reactions to demonstrate that the incorporation of an amorphous PMAC block within the core does not disrupt CDSA and can be used to load the cylindrical nanoparticles with cargo.
Royal Society (Great Britain), Engineering and Physical Sciences Research Council (EPSRC), European Research Council (ERC)
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Szablan, Zachary Peter Chemical Sciences & Engineering Faculty of Engineering UNSW. "Living free radical and photo initiation studies of acrylate, methacrylate and itaconate polymerization systems." 2008. http://handle.unsw.edu.au/1959.4/41255.
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This thesis work has focused on the study of itaconate monomers and photo-initiation processes in acrylate, methacrylate and itaconate monomer systems. Novel information pertaining to photo-initiator derived radical species and their reactivity, as well as the behaviour of itaconate polymerization systems is presented in detail. The knowledge gained from the photo-initiation studies is utilized as a precursor to mark polymer chains using nitrones as radical spin traps and the applicability of this technique discussed. The sterically hindered monomers dimethyl itaconate (DMI), di-n-butyl itaconate (DBI) and dicyclohexyl itaconate (DCHI) were polymerized via reversible addition fragmentation chain transfer (RAFT) free radical polymerization. The RAFT mediated polymerization of these monomers displayed hybrid living behaviour (a mix of conventional and living free radical polymerization characteristics) of varying degrees depending on the molecular structure of the RAFT agent employed. DCHI was also polymerized using atom transfer radical polymerization (ATRP). The resulting molecular weight distributions are broad for the RAFT mediated systems (1.2 ≤ PDI ≤ 3.4). The molecular weight distributions generated via the ATRP of DCHI are narrower (1.2 ≤ PDI ≤ 1.5). Chain transfer to monomer constants for the itaconate monomers DMI, DBI and DCHI have been determined at 60 ??C (CDMI = 1.4⋅10-3, CDBI = 1.3⋅10-3 and CDCHI = 1.0⋅10-3) and are relatively large in comparison to similar 1,1-disubstituted systems, suggesting that the transfer to monomer reaction is significant. PREDICI?? simulations confirm that a significant chain transfer to monomer step results in broad molecular weight distributions. Viscosity of the polymerizing system has also been shown to be an important factor in the resulting width of the molecular weight distributions. Chain extension of RAFT capped pDCHI and pDBI yield molecular weight distributions that progressively shift to higher molecular weights. Thermogravimetric analysis (TGA) of pDCHI-block-pStyrene copolymers indicates thermal degradation in two separate steps for the pDCHI and pStyrene blocks. Conventional pulsed laser polymerization coupled with size exclusion chromatography (PLP-SEC) as well as multi-pulse pulsed laser polymerization (MP-PLP) has been employed to study the depropagation kinetics of DMI, DBI DCHI and di(4-tert butylcyclohexyl) itaconate (DBCHI). The effective rate coefficient of propagation, kp eff, was determined for DMI, DBI and DCHI in bulk and solution of cyclohexanone (DCHI), N-methylformamide (DMI and DBI) and anisole (DBCHI) for monomer concentrations between 0.7 < cM 0 < 7.1 mol L-1 in a wide temperature range (0 < T < 90 ??C). The resulting Arrhenius plots (i.e. ln kp eff vs. 1/RT) displayed a significant curvature in the higher temperature regimes and were analyzed in their respective linear and curved sections to yield the activation parameters of the forward and reverse reaction. Mark-Houwink-Kahn Sakurada parameters for pDBI and pDBCHI were determined in tetrahydrofuran at 40 ??C using triple detection gel permeatation chromatography. High resolution Electrospray Ionization - Quadrupole Ion Trap Mass Spectrometry (ESIMS) was applied to study the polymeric product spectrum generated by the pulsed laser polymerization (PLP) of methyl methacrylate (MMA), methyl acrylate (MA), butyl acrylate (BA) and DMI at temperatures ≤ 0 ??C in the presence of various photo-initiators including 2,2-dimethoxy-2-phenylacetophenone (DMPA), benzoin, benzil, benzoin ethyl ether (BEE) 2,2-azobisisobutyronitrile (AIBN) and bis(2,4,6-trimethyl-benzoyl)- phenylphosphinoxide (Irgacure 819) to study the reactivity of primary and potential secondary derived radical fragments from photolytically induced fragmentation. Termination products, both combination and disproportionation, were identified with high accuracy. Results have been compiled in a user friendly table presenting the reactivity of the various photolysis product fragments towards the different monomers. Energy deposition into the MA/photo-initiator systems is found to have no influence on the product distributions of the MA polymers produced via photo-initiation under the conditions examined. For various photo-initiators employed, products congruent to that of chain transfer to monomer species in the DMI photo-polymerizations are observed, conclusively illustrating that chain transfer to monomer is a significant reaction pathway in itaconate free radical polymerizations. Both the benzoyl and acetal fragments generated as a result of DMPA photo cleavage were found to initiate and highly likely terminate polymerization. Under the conditions studied, the acetal radical produced upon DMPA photolysis fragment further to yield methyl radicals which seem to act predominantly as terminating moieties. Both the benzoyl and ether fragments produced as a result of benzoin photo cleavage were found to act as initiating and probable terminating species, indicating that the ether radical fragment does not act exclusively as a terminating species. Additionally, increasing laser intensity and/or irradiation repetition rate (i.e., energy deposition into the system) results in more complex product distributions of the MMA polymers produced via photo-initiation (with the exception of AIBN). Temperature was determined to have a minor influence on the resulting product distribution under the conditions examined. Polymerization systems utilizing Irgacure 819 give complex product spectra due to the formation of second generation radical species resulting in several initiator fragments incorporated into a single polymer chain. A novel method utilizing PLP in free radical polymerization has been developed for marking of polymer chains with radical spin traps. By introducing a so-called marker (nitroxide derived from a nitrone), which specifically terminates propagating radicals via combination, a polymer subdistribution is generated which can be measured by ESI-MS and may potentially be utilized to determine propagation rate coefficients of ultimate accuracy. The general methodology of the technique in which such marker radicals are generated via reaction of an initiating radical with a nitrone is demonstrated on the examples of butyl acrylate (BA) and vinyl acetate (VAc).
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El, Rezzi Véronique. "Chain-transfer kinetics for free-radical homo- and coplymerizations of styrene and methyl methacrylate in supercritical carbon dioxide." Doctoral thesis, 2001. http://hdl.handle.net/11858/00-1735-0000-0006-B0E3-8.
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