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Peterson, Tod J. "Nonlinear predictive control of a semibatch polymerization reaction". Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/10982.
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Chatzidoukas, Christos. "Control and dynamic optimization of polymerization reaction processes". Thesis, Imperial College London, 2004. http://hdl.handle.net/10044/1/8237.
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Prehl, Janett, i Constantin Huster. "Morphology on Reaction Mechanism Dependency for Twin Polymerization". MDPI, 2019. https://monarch.qucosa.de/id/qucosa%3A34346.
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An in-depth knowledge of the structure formation process and the resulting dependency of the morphology on the reaction mechanism is a key requirement in order to design application-oriented materials. For twin polymerization, the basic idea of the reaction process is established, and important structural properties of the final nanoporous hybrid materials are known. However, the effects of changing the reaction mechanism parameters on the final morphology is still an open issue. In this work, the dependence of the morphology on the reaction mechanism is investigated based on a previously introduced lattice-based Monte Carlo method, the reactive bond fluctuation model. We analyze the effects of the model parameters, such as movability, attraction, or reaction probabilities on structural properties, like the specific surface area, the radial distribution function, the local porosity distribution, or the total fraction of percolating elements. From these examinations, we can identify key factors to adapt structural properties to fulfill desired requirements for possible applications. Hereby, we point out which implications theses parameter changes have on the underlying chemical structure.
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Li, Xiaopei. "Elucidation of the Termination Reaction Mechanism of Radical Polymerization". Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263689.
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Kaßner, Lysann, Kevin Nagel, R. E. Grützner, Marcus Korb, Tobias Rüffer, Heinrich Lang i Stefan Spange. "Polyamide 6/silica hybrid materials by a coupled polymerization reaction". Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-197628.
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Polyamide 6/SiO2 hybrid materials were produced by a coupled polymerization reaction of three monomeric components namely 1,1′,1′′,1′′′-silanetetrayltetrakis-(azepan-2-one) (Si(ε-CL)4), 6-aminocaproic acid (ε-ACA) and ε-caprolactam (ε-CL) within one process. Si(ε-CL)4 together with ε-ACA has been found suitable as a precursor monomer for the silica and PA6 components. The accurate adjustment of the molar ratio of both components, as well as the combination of the overall process for producing the polyamide 6/SiO2 hybrid material with the hydrolytic ring opening polymerization of ε-caprolactam is of great importance to achieve homogeneous products with a low extractable content. Water in comparison with ε-ACA has been found unsuitable as an oxygen source to produce uniformly distributed silica. The procedure was carried out in a commercial laboratory autoclave at 8 bar initial pressure. The molecular structure and morphology of the hybrid materials have been investigated by solid state 29Si and 13C NMR spectroscopy, DSC and FTIR spectroscopy and electron microscopy measurementsDieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
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Santos, Vinícius Nobre dos. "Estudo cinético da copolimerização estireno-divinilbenzeno". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-22072016-162616/.
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As redes poliméricas são materiais amplamente estudados, pois suas propriedades especiais permitem que sejam aplicadas em áreas como indústria de fertilizantes, medicina, bioquímica, análises químicas dentre outras. A microestrutura de uma rede polimérica, em geral, exerce grande influência sobre as propriedades macroscópicas desses materiais e o interesse da influência dessa microestrutura nas propriedades finais são de interesse estratégico. As reações de ciclização influenciam no controle da microestrutura das redes poliméricas, é sabido que um aumento na diluição do sistema aumenta a incidência deste tipo de reações. A modelagem matemática da copolimerização do estireno-divinilbenzeno é um assunto amplamente estudado, porém poucos estudos foram realizados considerando as reações de ciclização com uma cinética definida e não um problema tipo caixa-preta. Este trabalho teve como principal objetivo o estudo da copolimerização de estireno-divinilbenzeno em solução e sua modelagem matemática com a inclusão das reações de ciclização intramoleculares. Sendo assim, reações de copolimerização de estireno-divinilbenzeno em soluções com baixas concentrações de monômeros foram realizadas em batelada em um reator de vidro, inicialmente foram utilizados dois modelos matemáticos para estudar o comportamento do sistema nestas condições, denominados: Modelo A e Modelo B. O Modelo A foi desenvolvido através do balanço de massa de todas as espécies no meio reacional e inclusão das reações de ciclização. O tamanho máximo dos polímeros mortos considerados neste modelo foi de 300 unidades monoméricas, pois devido à diluição acreditava-se que este tamanho máximo abrangesse todos os tamanhos de polímeros mortos, porém sua comparação com dados experimentais mostrou o contrário. O Modelo B foi baseado no modelo desenvolvido por Aguiar (2013) e utiliza o balanço de massa para as espécies não poliméricas e método dos momentos para as espécies poliméricas (radicais poliméricos e polímeros mortos). Este modelo utiliza também o Fracionamento Numérico para determinação das massas moleculares e ponto de gel, as reações de ciclização foram incluídas através do Método dos Caminhos. Quando comparados aos dados experimentais, o Modelo B mostrou-se mais realista com menores tempos de simulação e com menores problemas numéricos que o Modelo A, portanto este foi utilizado para o estudo do sistema em questão. Os resultados apresentados através do Modelo B indicam que o parâmetro atribuído à cinética das ligações cruzadas (Cp) foi de 0,05 e o valor do parâmetro de ciclização do menor segmento ciclizável (3 unidades monoméricas) foi de 130 s-1 para a temperatura de 90ºC, os valores para os demais tamanhos foram calculados através da equação de Rolfes e Stepto. Este trabalho é uma continuação ao trabalho de Aguiar (2013) e seus resultados mostraram que as simulações das variáveis: concentração de duplas ligações pendentes, Massa Molecular Mássica Média (Mw) e polidispersidade aproximaram-se mais dos dados experimentais quando as ciclizações são incluídas no modelo quando comparadas à abordagem sem a inclusão das reações de ciclização.Polymer networks are widely studied materials; their especial properties allow them to be applied in areas such as the fertilizer industry, medicine, biochemistry, chemical analysis among others. In general, the polymer network microstructure has influence in macroscopic properties of materials, hence the interest of such microstructure in final properties are of strategic interest. The cyclization reactions influence in the microstructure control of polymer networks. It is known that an increase in systems dilution can increase the cyclization reactions incidence. Mathematical modeling of copolymerization of styrene-divinylbenzene is a widely studied subject, but few studies have been conducted considering the cyclization reactions with a defined kinetic and not a problem black-box type. This work aimed to study the styrene-divinylbenzene copolymerization solutions and their mathematical modeling with the inclusion of intramolecular cyclization reactions. Thus, solution copolymerization of styrene and divinylbenzene was carried out at low concentration of monomers in batch reactor. Two mathematical models were initially used to analize the behavior of the system, which were called: Model A and Model B. The Model A was developed by molar balance of species in the reaction medium and includes cyclization reactions, which were considered to happen in polymer chains with 300 or less monomer units. Due the dilution was believed that this number of units covering all sizes of dead polymers, but comparison between Model A an experimental data proved otherwise. The Model B was based in model of Aguiar (2013), and uses the mass balance for non-polimerics species and moments methods for polimerics species. Model B also uses numerical fractionation for average molecular weight and gel point determination, and the method of paths to approach cyclization reactions. When compared to experimental data, Model B proved more realistic, presenting shorter simulation times and less numerical problems than Model A. Therefore Model B was chosen to represent the system. The results presented by Model B indicate that the parameter assigned to the kinetics os crosslink (Cp) was fitted at 0,05 and cyclization rate constant for paths with 3 monomer units was fitted 130 s-1 at temperature of 90°C. The cyclization rate constants for longer paths were calculated trough Rolfes and Steptos equation. This work is a follow up to Aguiars work (2013) and the results showed that the simulation of variables: concentration of pendant double bonds, average molecular weight and polidispersity better predicted when the cyclization rate constants are greater than zero.
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Tirumala, Vijaya Raghavan. "Reaction control in quiescent systems of free-radical retrograde-precipitation polymerization /". Available online. Click here, 2003. http://sunshine.lib.mtu.edu/ETD/DISS/tirumalav/Dissertation.pdf.
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Wasylyshyn, Dwayne Andrew. "Molecular dynamics and reaction kinetics during polymerization using dielectric spectroscopy and calorimetry". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0006/NQ42886.pdf.
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Asano, Shusaku. "Rational Design of Micromixers and Reaction Control in Microreactors". Kyoto University, 2018. http://hdl.handle.net/2433/232008.
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Abyazisani, Maryam. "Molecular reactions on surfaces: Towards the growth of surface-confined polymers". Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/130754/1/Maryam_Abyazisani_Thesis.pdf.
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High-quality low-dimensional polymer synthesis is a promising route to fabricating high-performance functional nanomaterials. The Ullmann reaction is a frequently-employed reaction with the drawback of unwanted metal-halide byproducts. This project investigates two approaches for the formation of byproduct-free ordered polymers: (a) employing decarboxylation coupling as a "clean reaction" and (b) removal of the metal-halide byproduct by etching with a beam of atomic hydrogen after Ullmann coupling. Both approaches provide new insight into molecule–substrate interactions, intermolecular interactions and the halogen's effect on the polymerization reaction and products.
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Ponnupandian, Siva. "Macromolecular Engineering with Tailor-made Functional Fluoropolymers via RAFT Polymerization and Diels-Alder Reaction". Thesis, Curtin University, 2021. http://hdl.handle.net/20.500.11937/82865.
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Fluoropolymers, owing to its unique properties such as excellent water and oil resistance, chemical resistance, and thermal stability they have been widely used in developing speciality coatings. This thesis reports on the preparation of well-defined functional fluoropolymers such as block and random copolymers based on fluoroacrylates and fluoromethacrylates along with different comonomers via reversible addition-fragmentation chain-transfer (RAFT) polymerization. The potential application of these fluoropolymers mainly as a coating material along with other different properties such as self-healing behaviour was studied.
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Zhang, Manrui. "Studies of a click reaction route to antimicrobial polymer latexes". Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/studies-of-a-click-reaction-route-to-antimicrobial-polymer-latexes(b6c2b634-ec41-44b6-a88f-2d908e1f422c).html.
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The objective of this project was to prepare alkyne-functionalized polymer latexes using surfactant-free emulsion polymerization, and then functionalize these polymer latexes with three quaternary ammonium azides via Cu(I)-catalyzed azide/alkyne cycloaddition (CuAAC) in order to produce antimicrobial polymer latexes. Three quaternary ammonium azides with different linear alkyl chain lengths (C4, C8 and C12) were successfully synthesised in high yield ( > 70%) using established procedures, and their purity determined by elemental analysis, Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. Alkyne-functionalized polymer latexes were prepared via surfactant-free emulsion polymerization using 2,2'-azobis(2-methylpropionamidine)dihydrochloride (AIBA) as initiator, [2-(methaccryloyloxy)ethyl]trimethylammonium chloride (MATMAC) as cationic comonomer, propargyl methacrylate (PMA) to provide the alkyne groups, and for some latexes, ethylene glycol dimethacrylate (EGDMA) as crosslinking comonomer. The effects of temperature and the concentrations of AIBA, MATMAC, PMA and EGDMA on monomer conversion, the rate of polymerization, particle diameter and colloidal stability have been investigated. The studies showed that the very high rates of polymerization were due to high values of the number of radicals per particle (in the range 3-2300). The observations also determined that the reaction conditions required to produce small particles (diameter of 150-350 nm) of narrow size distribution were: 75 oC reaction temperature, AIBA at 0.2 wt% to the total mass of monomer, MATMAC level of smaller or equal to 12 mol% to total monomer (including MATMAC), and EGDMA level of < 2.0 mol% to total monomer (excluding EGDMA). Three series of alkyne-functionalized polymer latexes have been synthesised using these conditions: non-crosslinked (NCL), crosslinked (CL) and core-shell (CS). All the latex particles were functionalized with the three quaternary ammonium azides by CuAAC. Zeta potential analysis, FTIR and Raman spectroscopy analysis confirmed the success of the click reactions. The quantitative analysis of FTIR and Raman spectra showed similar values of conversion of click reaction for both NCL and CL particles, indicating NCL and CL particles have similar swellability. The data also showed that significantly higher click reaction conversions were achieved for CS particles (around 60%) than for NCL/CL particles (less than 40%), which indicates that the click reaction only occurred at the surface of particles and that a higher proportion of alkyne groups are located on the surface of CS particles than on NCL/CL particles. The antimicrobial properties of all QAAs, MATMAC, NCL, CL and CS polymer latexes against E. coli bacteria (ATCC 25922) have been investigated using a modified liquid microdilution method in M9 medium, which was shown not to affect latex colloidal stability. It was found that all the polymer latexes showed much higher antimicrobial activities (MIC 6.5-75 µg ml-1) than many antimicrobial polymers reported recently in the literature (MIC 100-2000 µg ml-1); (Ganewatta, M.S. and C.B. Tang, Controlling macromolecular structures towards effective antimicrobial polymers. Polymer, 2015. 63: p. A1-A29). Polymer latexes with clicked-on QAAs showed significantly higher antimicrobial activities than the original latexes. The magnification of the increase in antimicrobial properties of CS particles after click reaction (~3.5 times) was greater than for NCL/CL particles (~2.5 times), showing that a larger amount of QAAs have been clicked onto the surface of CS particles than NCL/CL particles and that the clicked-on QAAs enhance the antimicrobial activity significantly.
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Mendez, Ecoscia Ana Carolina. "Experimental Study of Emulsion Polymerization of Vinylidene Fluoride". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1203.
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Le développement d’un procédé de polymérisation en émulsion est complexe de par la nature hétérogène de ce type de réaction. En outre, dans le cas de la polymérisation en émulsion du fluorure de vinylidène, la difficulté est d’autant plus accrue que le monomère est habituellement en phase gazeuse ou supercritique dans les conditions d’intérêt. Or la littérature manque d’informations concernant ce type de procédé de synthèse du PVDF sous une pression comprise entre 30 bar et 90 bar.Ainsi cette thèse a pour objectif de contribuer à une meilleure compréhension des mécanismes cinétiques et de stabilisation intervenants dans la polymérisation radicalaire en émulsion du VDF dans des conditions supercritiques et, plus particulièrement, de fournir des données expérimentales nécessaires à l’élaboration de futurs modèles.Avant même d’entreprendre les études expérimentales, cette thèse s’intéresse d’abord aux aspects d’installation et d’automatisation de l’unité de polymérisation ainsi qu’au démarrage et à l’optimisation du réacteur. Ensuite, plusieurs tests sont réalisés afin de comprendre certaines caractéristiques du latex produit ainsi que certaines propriétés du tensioactif fluoré. Une nouvelle méthode a spécialement été développée afin de suivre le phénomène de coagulation des particules de polymère.Finalement des réactions sont réalisées par lot et en semi-continu et une étude paramétrique des conditions opératoires et de la composition des réactifs est effectuée afin d’évaluer leur impact sur l’évolution de la polymérisation en émulsion. Notamment, le profil de vitesse de polymérisation est obtenu par calorimétrie, à partir d’une approche pratique fondée sur un estimateur d’état en cascade, ainsi que sur la mesure de la consommation de monomère, et sur l’analyse gravimétrique réalisée par prélèvementThe heterogeneous nature of the conventional emulsion polymerization can render the process quite complex. In the case of the emulsion polymerisation of vinylidene fluoride (VDF), the situation is more complicated than for the majority of industrial processes because the monomer is typically either a gas or a supercritical fluid under the polymerization conditions of interest. Given the relatively high pressure required for this process (30bar
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Borchardt, Lars, i Sven Grätz. "Mechanochemical polymerization – controlling a polycondensation reaction between a diamine and a dialdehyde in a ball mill". Royal Society of Chemistry, 2016. https://tud.qucosa.de/id/qucosa%3A30231.
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The mechanochemical polycondensation between a diamine and a dialdehyde constitutes a sustainable alternative to classical solvent-based polymerization reactions. This process not only allows for a higher conversion and a shorter reaction time as compared to standard solvent-based syntheses of this conjugated polymer, but the reaction can also be adjusted by the energy introduced via the ball mill.
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Borchardt, Lars, i Sven Grätz. "Mechanochemical polymerization – controlling a polycondensation reaction between a diamine and a dialdehyde in a ball mill". Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-221833.
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The mechanochemical polycondensation between a diamine and a dialdehyde constitutes a sustainable alternative to classical solvent-based polymerization reactions. This process not only allows for a higher conversion and a shorter reaction time as compared to standard solvent-based syntheses of this conjugated polymer, but the reaction can also be adjusted by the energy introduced via the ball mill.
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Han, Joong Jin. "Kinetics and morphology of metallocene catalyzed syndiospecific polymerization of styrene in homogeneous and heterogeneous reaction systems". College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/8880.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2008.Thesis research directed by: Dept. of Chemical and Biomolecular Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Kayahara, Eiichi. "Studies on the Precision Control of Polymer Structure Based on Heteroatom-Mediated Living Radical Polymerization Reaction". 京都大学 (Kyoto University), 2011. http://hdl.handle.net/2433/142245.
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Zhan, Gaolei. "Supramolecular networks and on surface polymerization studied by scanning tunneling microscopy". Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCD069/document.
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Ce travail présente les études, par microscopie à effet tunnel (STM) sous ultravide, d’une part de la formation de réseaux supramoléculaires, résultant de l’auto-assemblage des précurseurs organiques sur les surfaces Cu(111), Au(111), Si(111)-B et HOPG, et d’autre part, de l’étude de réactions chimiques sur les surfaces Cu(111), Au(111) et HOPG. Le premier chapitre décrit l’état de l’art des réseaux supramoléculaires ainsi que les réactions chimiques sur les surfaces. Le deuxième chapitre présente le dispositif expérimental et les théories sous-jacentes, ainsi que les préparations des substrats, de la pointe et la méthode de déposition des molécules.Le troisième chapitre présente les réseaux supramoléculaires formés par les dépositions des molécules fonctionnalisées par des atomes de brome ou d’azote sur les surfaces Cu(111) et Si(111)-B. Dans tous les cas, le rôle de la surface est prédominant lors de la formation des réseaux. Sur Cu(111), deux réseaux linéaires sont stabilisés par des interactions organométalliques entre les adatomes de Cu et les molécules organiques. Sur Si(111)-B, les réseaux formés sont commensurables avec la reconstruction √3 × √3 de la surface. En fonction de la compétition entre les interactions intermoléculaires et molécule-surface, les réseaux peuvent être 2D ou 1D.Le quatrième chapitre présent le premier exemple de polymérisation radicalaire sur une surface. Pour ce faire, quatre molécules de type arylalkyléthers et deux molécules arylalkanes furent synthétisées et déposées sur les surfaces de Cu (111), Au (111) et HOPG. Le mécanisme proposé pour cette réaction débute par une étape d’initialisation grâce à un processus de transfert inélastique d’électron tunnel (IET), générant des radicaux libres qui peuvent ensuite polymérisés par voie radicalaire sur la surfaceThis work deals with the investigation, by means of scanning tunneling microscopy under ultra-high vacuum, of supramolecular networks resulting from the self-assembly of organic precursors on surfaces such as Cu(111), Au(111), Si(111)-B and HOPG, but also the investigation of on-surface reactions. The first chapter describes the state-of-the-art of supramolecular networks and on-surface reactions on surfaces. The second chapter presents the experimental setup and theoretical concepts, as well as the preparations of the substrates, the probe tip and the method of molecular deposition.The third chapter presents the supramolecular networks formed by the depositions of molecules functionalized by bromine atoms or nitrogen atoms on the Cu(111) and Si(111)-B surfaces. For both cases, the surface plays a key role in the formation of networks: on Cu(111), the two linear networks are stabilized by metal-organic interactions between the Cu adatoms and the organic molecules; on Si(111)-B, the nanoarchitectures are commensurable with the reconstruction √3 × √3 of the surface. As function of the competition between the intramolecular and intermolecular interactions, the networks could be 2D or 1D.The fourth chapter presents the first example of on-surface radical polymerization, which is developed by the tandem synthetic method. For this end, four arylalkylether molecules and two arylalkane molecules are synthetized and deposited on different types of surfaces such as Cu (111), Au (111) and HOPG. The proposed mechanism suggests that this reaction is initialized by the inelastic electron tunneling (IET) process, which provides the free and stable radicals for the further on surface radical polymerization
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Hill, Gavin T. H. "The preparation and testing of novel biodegradable surfactants using poly(lactic acid) as the backbone, by a one-step ring opening polymerisation reaction /". St Andrews, 2008. http://hdl.handle.net/10023/746.
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XUE, YUAN. "Quantum Mechanical Calculations on Ring-opening Reactions of Hexachlorophosphazenes". University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1627595429444473.
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Dubey, Satya P. "Mathematical modelling and simulation of continuous, highly precise, metal/eco-friendly polymerization of Lactide using alternative energies for reaction extrusion". Thesis, Cranfield University, 2016. http://dspace.lib.cranfield.ac.uk/handle/1826/11253.
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Polylactic acid (PLA) is one of the most promising bio-compostable and biodegradable thermoplastic made from renewable sources. PLA, is typically obtained by polymerising lactide monomer. The technique mainly used for ring opening polymerization (ROP) of Lactide is based on metallic/bimetallic catalyst (Sn, Zn, and Al) or other organic catalysts in suitable solvent. However, the PLA synthesized using such catalysts may contain trace elements of the catalyst, which may be toxic. In this work, reactive extrusion experiments using stannous octoate Sn(Oct)2 and tri-phenyl phosphine (PPh)3 were considered to perform ROP of lactide monomer using ultrasound as an alternative energy (AE) source for activating and/or boosting the polymerization. Mathematical model of ROP of lactide, was developed to estimate the impact of reaction kinetics and AE source on the polymerization process. Ludovic® software, a commercial code was used. It was adopted for the simulation of continuous reactive extrusion of PLA. Results from experiments and simulations were compared to validate the simulation methodology. Results indicate that the application of AE source in reaction process boost the PLA formation rate. Result obtained through Ludovic simulation and experiments were validated. It was shown that there is a case for reducing the residence time distribution (RTD) in Ludovic due to the ‘liquid’ monomer flow in the extruder. This change in the parameters resulted in validation of the simulation. However, it was concluded that the assumption would have to be established by doing further validations. The simulation model includes the details of kinetics of reactions involved with in the process and helps to upscale the reaction output. This work also estimates the usefulness and drawbacks of using different catalysts as well as effect of alternative energies and future aspects for PLA production.
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Meng, Zhiyong. "Self-assembly and chemo-ligation strategies for polymeric multi-responsive microgels". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29743.
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Thesis (Ph.D)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009.Committee Chair: Lyon, Louis; Committee Member: Breedveld, Victor; Committee Member: Bunz, Uwe; Committee Member: Collard, David; Committee Member: Srinivasarao, Mohan. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Park, Jinwoo. "Synthesis and Development of Helical Functional Polymers using Advanced Chiral Liquid Crystal Fields". 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/199336.
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Evans, Jessica. "Synthesis of Highly Fluorinated Diels-Alder Polyphenylenes". Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/39179.
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Fluoropolymers have useful properties including high thermal stability, chemical resistance, low dielectric constants, and both hydrophobic and oleophobic character, as compared to non-fluorinated analogues. Meanwhile, Diels-Alder polyphenylenes (DAPPs) are known for thermal stability as well as their rigid structure and glassy physical characteristics, which have led to a variety of film and membrane applications. This dissertation merges these two fields by demonstrating a novel and general synthetic approach to highly fluorinated DAPPs. These polymers are expected to retain the physical characteristics of glassy, non-fluorinated DAPPs while also incorporating the desirable attributes of fluoropolymers.
The polymer synthesis described herein is based on the well-established polycondensation of bis(cyclopentadienone) (CPD) monomers and dialkynes. Our first main scientific contribution is a general method for preparing CPDs containing both a fluoroaromatic linker and variable fluoroaromatic head-groups. Our CPD synthesis uses nucleophilic aromatic substitution reactions of cyclopentadienyl anions and perfluoroarenes, as well as a new catalytic method of converting cyclopentadiene methylene (CH₂) groups into the corresponding ketones (C=O) that is the primary dissertation subject of Brian S. Hickory in our laboratory. The overall synthesis is notable for its use of inexpensive starting materials, its efficiency, and its structural versatility.
Our second main contribution is the synthesis of novel highly fluorinated Diels-Alder polyphenylenes (DAPPs). Fluorinated DAPPs varied in their molecular weight, in the identity of the lateral fluoroaryl substituent (pentafluoro-phenyl or tetrafluoro-4-pyridyl), and in the structure of the aromatic dialkyne monomer. These polymers are glassy materials with high glass transition temperatures and high thermal stability. Since the polyphenylene structure is intrinsically rigid, the polymers form brittle films even at molecular weights of over 30,000 (Mw). Unlike many fluoropolymers, the fluorinated DAPPs are freely soluble in common organic solvents such as tetrahydrofuran and chloroform. An unknown side reaction competes with the polymer propagation and reduces the highest obtainable molecular weights, which limit the ability to form films. However, a stoichiometric imbalance leads to highly fluorinated polyphenylene oligomers terminated with either alkyne or CPD end groups (Mn = 9000).
Because preliminary experiments had shown that the desired Diels-Alder propagation reaction was slower than expected, we also undertook a detailed model study of the reaction conditions needed for Diels-Alder reactions of fluorinated CPDs and aromatic alkynes. These experiments showed that protic polar solvents (e.g., m-cresol) and conventional heating at ca. 150 °C optimize reaction rate while minimizing side-reactions that can contribute to lower molecular weight in corresponding polymerization reactions.Ph. D.
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Virtanen, Otto L. J. [Verfasser], Walter [Akademischer Betreuer] Richtering i Sebastian [Akademischer Betreuer] Seiffert. "Insight into precipitation polymerization of N-isopropylacrylamide : reaction mechanism, particle formation and particle structure / Otto L. J. Virtanen ; Walter Richtering, Sebastian Seiffert". Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1130792501/34.
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Primpke, Sebastian. "Mechanism and Kinetics of Catalyzed Chain Growth". Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2014. http://hdl.handle.net/11858/00-1735-0000-0022-5DA6-1.
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Rabelo, Maria Cristiane. "SÃntese enzimÃtica e separaÃÃo cromatogrÃfica de isomalto-oligossacarÃdeos de cadeia longa". Universidade Federal do CearÃ, 2012. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=10079.
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CoordenaÃÃo de AperfeiÃoamento de NÃvel SuperiorOs isomalto-oligossacarÃdeos prÃ-biÃticos sÃo carboidratos capazes de chegar intactos ao intestino grosso, onde sÃo metabolizados pelas bifidobactÃrias e lactobacilos ali presentes, estimulando o seu crescimento e proporcionando efeitos benÃficos à saÃde. Podem ser obtidos por sÃntese enzimÃtica, entretanto, os substratos nÃo consumidos, frutose e dextrana tambÃm estÃo presentes apÃs a formaÃÃo dos isomalto-oligossacarÃdeos. Este trabalho teve por objetivo a sÃntese enzimÃtica e a separaÃÃo de isomalto-oligossacarÃdeos prÃ-biÃticos por cromatografia de troca iÃnica em escala preparativa. A primeira parte da tese consistiu em investigar o efeito de diferentes estratÃgias de alimentaÃÃo de sacarose e maltose ao meio reacional sobre o alongamento da cadeia dos isomalto-oligossacarÃdeos. A sÃntese foi realizada adicionando-se 1UI/mL da enzima ao meio reacional contendo como substrato os aÃÃcares sacarose e maltose. Na primeira estratÃgia, houve a adiÃÃo somente de sacarose ao meio reacional a cada 2 horas, durante 8 horas. Na segunda estratÃgia, houve a adiÃÃo da mistura de sacarose e maltose ao meio reacional a cada 2 horas, durante 8 horas. Na terceira estratÃgia houve, a cada hora, a adiÃÃo da mistura de sacarose e maltose, durante seis horas. ApÃs este perÃodo, houve adiÃÃo somente de sacarose durante seis horas. A Ãltima estratÃgia de alimentaÃÃo, resultou no alongamento da cadeia dos isomalto-oligossacarÃdeos atà grau de polimerizaÃÃo nove, alÃm do aumento da concentraÃÃo dos mesmos (79,04 g/L) a nÃveis consideravelmente superiores aos reportados na literatura. Na segunda parte da tese, foi avaliada a influÃncia da forma catiÃnica de fases estacionÃrias cromatogrÃficas na separaÃÃo dos isomalto-oligossacarÃdeos. As isotermas de adsorÃÃo dos isomalto-oligossacarÃdeos, monossacarÃdeos e dissacarÃdeos foram determinados em colunas preparativas empacotadas com resina de troca iÃnica em diferentes formas catiÃnicas (K+, Ca2+, H+ e Na+) à 25ÂC. Todas as fases adsorveram os aÃÃcares com capacidade variÃvel, segundo a ordem de afinidade: frutose > glicose > maltose > IMOs com grau de polimerizaÃÃo crescente. Foi verificado que a forma catiÃnica H+ apresentou melhor desempenho para ser utilizada em unidades de leito mÃvel simulado permitindo a separaÃÃo de isomalto-oligossacarÃdeos prÃ-biÃticos com menor diluiÃÃo e maior produtividade. No entanto, a resina na forma K+ apresentou rendimento apenas ligeiramente inferior, sendo mais compatÃvel com os requisitos de tamponamento da reaÃÃo enzimÃtica.
Prebiotic isomalto-oligosaccharides (IMOs) are carbohydrates able to reach the large bowels intact, where they are metabolized by bifidobacteria and lactobacillus, stimulating their growth and providing beneficial health effects. They may be obtained by enzymatic synthesis using sucrose and maltose as precursors. However, non consumed substrates, fructose and dextran are present together with the produced isomalto-oligosaccharides. This work aimed the optimization of the enzymatic synthesis and the separation of prebiotic isomalto-oligosaccharides by ion exchange chromatography on semipreparative scale. The first part of the thesis investigated the effect of different feeding strategies of sucrose and maltose to the reaction medium on the chain elongation of isomalto-oligosaccharides. The synthesis was performed by adding 1UI/mL of enzyme to reaction medium containing sucrose and maltose as substrate. In the first strategy, only sucrose was added to the reaction medium every 2 hours for 8 hours. In the second strategy, a mixture of sucrose and maltose was added to the reaction medium every 2 hours for 8 hours. In the third strategy, at every hour, a mixture of sucrose and maltose was added for six hours. Then, only sucrose was added at every hour for more six hours. The latter strategy resulted of isomalto-oligosaccharides chain elongation up to degree of polymerization of 9. The concentration of IMOs (79.04 g/L) was also observed. In the second part of the thesis, the influence of the cationic form of the chromatographic stationary phase in the isomalto-oligosaccharides separation was evaluated. Adsorption isotherms of isomalto-oligosaccharides, maltose, glucose and fructose were determined in preparative columns packed with ion-exchange resin in different cationic forms (K+, Ca2+, H+ and Na+) at 25ÂC. All stationary phases adsorbed the sugars with variable capacities, following the same order of affinity: fructose > glucose > maltose > IMOs with increasing degrees of polymerization. It was found that the resin in H + form presented the best performance to be used in simulated moving bed units, allowing for the separation of prebiotic isomalto-oligosaccharides with lower dilution and higher productivity. Nevertheless, the resin K+ had only a slighty inferior performance and this cation is more compatible with buffer requirements of the enzymatic synthesis.
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Ribeiro, Marcos Sobral. "Sistema calorimétrico e software para análise da polimerização de compostos de metacrilato de metila, pela variação da exotermia da reação". Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-16122013-111259/.
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A calorimetria vem a ser uma importante técnica para análise dos processos de polimerização. Dado os benefícios que proporciona seu uso não deve estar limitado somente a grandes empresas, mas também nas micro e pequenas empresas, apoiando-as nas melhorias de seus processos e produtos, motivo este que norteia o desenvolvimento do presente estudo. A validação do sistema proposto baseou-se em comparar seu desempenho frente a um calorímetro tradicional, visando identificar sua capacidade de fornecer informações compatíveis, a um grau de confiança adequado, mesmo com as diferenças existentes. Realizou-se então um ANOVA, que permitiu identificar a existência de outras diferenças importantes entre os sistemas. Porém mesmo frente as diferenças, os resultados quanto à entalpia de reação obtidos em ambos os equipamentos, são considerados estatisticamente similares. As diferenças existentes somente impactaram a variável tempo de pico de reação. Desta forma, foi possível confirmar a capacidade do equipamento proposto em prover resultados confiáveis quando mantidas as mesmas condições de ensaio, porém a um menor custo. No caso de se respeitar as diferenças entre os equipamentos quando da realização dos testes, torna-se possível obter uma eficiência global em torno de 61,21%, quanto a ensaios de polimerização por iniciação térmica. No caso de ensaios envolvendo mecanismos de oxi-redução, pode-se aqui obter um percentual de 40,82%.Calorimetry comes to be an important technique for the analysis of polymerization processes. It benefits provides the use not only for large companies, but also for micro and small businesses, assisting them to improve processes and qualified products. The validation of the proposed system was based on the comparison of its performance against one traditional calorimeter, to identify their ability to provide consistent, adequate level of confidence, even if the differences occurred. ANOVA was applied to identify the existence of other important differences between the systems. But even forward differences, the results regarding the reaction enthalpy obtained in both devices were considered statistically similar. Differences only reflected the variable reaction peak time. Thus, it was possible to confirm the capability of the proposed equipment to provide reliable results while maintaining the same test conditions, and at expected lower cost. In respect to the differences between the devices while tested, it becomes possible to obtain an overall efficiency at about 61.21% in polymerization by thermal initiation. For assays involving oxidation-reduction mechanisms, it can obtained an overall efficiency at about 40.82%.
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Hill, Gavin T. H. "The preparation and testing of novel biodegradable surfactants using poly(lactic acid) as the backbone, by a one-step ring opening polymerisation reaction". Thesis, University of St Andrews, 2009. http://hdl.handle.net/10023/746.
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A review of the chemistry of poly(lactic acid) was carried out with a focus on techniques and applications of PLA polymer and copolymers with reference to some of the work that has been accomplished over the last 20 years or so. A review of the characterisation techniques used to analyse PLA polymers and copolymers was also carried out giving reference to the equipment and methods used herein. An investigation into the potential of PLA as the hydrophilic portion of a polymeric surfactant was carried out. To develop PLA based surfactants, the ring opening polymerisation of lactide was carried out in a melt in the presence of a long chain alcohol (C₇ to C₂₀) or diol (C₄ & C₆) to produce AB or ABA type polymers that follow the traditional surfactant template. Stannous octanoate and 4-dimethylaminopyridine were typically used as catalysts due to their high activity and relative cheapness. PLA only shows good hydrophilicity with up to 12 lactic acid units in the chain. Above this the electrostatic interactions between polymer chains reduced water solubility. It was also noted that D,L-lactide produced more water soluble polymers (syndiotactic) than the enantiomerically pure L-lactide (isotactic polymer chains). An investigation of the hydrophobic properties of PLA was carried out to evaluate their usefulness for other biodegradable surfactant applications. To this end an investigation of sugars as the hydrophilic portion of the molecule was carried out. Due to problems with solubilising sugars, they were deemed unsuitable for use as initiatiors within the scope of this research. Choline chloride was then investigated as a potential hydrophilic initiator and indeed has produced some of the most water soluble of PLA polymers. Choline chloride presented several challenges as an initiator, its high melting point resulted in polar solvents such as t-butanol being employed. Alternatively, more success was achieved by preparation of a choline chloride eutectic mixture prior to the polymerisation. It was discovered that a choline chloride/urea eutectic mixture was capable of self initiation, thus required no further addition of catalyst, this result shows a potential step forward in PLA green chemistry. A final investigation into producing surface-active PLA in a one-pot process that required only a hydroxycarboxylate initiator was carried out. The production of PLA sodium or potassium salts was carried out in a melt polymerisation and the results show some promise. Initiators that have been employed include a range of a, b and g-hydroxycarboxylic acids. These work through tautomerisation to the alkoxide, which then initiates a living type polymerisation of lactide to produce surface-active polymers. As well as the synthesis of these polymers some analysis of the physical and aqueous properties of these materials was carried out. PLA sodium salts were shown to have reasonable surfactant ability (~45 mNm⁻¹) and low CMC values of around 5x10⁻⁹ mol cm⁻³. They were also shown to have some properties as emulsifiers, and in some cases showed non-Newtonian fluid behaviour such as shear-thinning (thixotropy) and shear-thickening (dilatant). The thermal characteristics of the polymers such as T[subscript]g and stability were assessed as well as their ability to retain water.
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Tchernook, Ivan. "Strategies for Computational Investigation of Reaction Mechanisms in Organic and Polymer Chemistry Using Static Quantum Mechanics". Doctoral thesis, Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-198756.
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This thesis presents computational studies of problems in the organic and polymer chemistry. The state-of-the art quantum chemical methods are used to gain further insight into the origin and the nature of the reactions in three different organic and polymer systems. The research questions are conceptually approached by identifying the key aspects. Then an appropriate strategy for the quantum chemical modeling is developed.
In the scope of the polymer chemistry, the novel synthesis technique of nanostructured materials, the so-called twin polymerization, is investigated. Using three model systems of increasing complexity the influence of the anion (trifluoroacetate) in the reaction system is investigated. The effect of the solvent polarity as well as the effect of the entropic contributions are also considered.
The rearrangement reaction of the volatile cyanotritylcarbenes is another topic. These carbenes readily rearrange to ethene main products, however also small amount of the unexpected heptafulvenes is formed. This unprecedented heptafulvene formation is modeled in detail and the energetics is systematically evaluated to identify most reasonable rearrangement pathways of the probable multiple alternative routes. Computational investigation of other tritylcarbenes with varying spectator substituents results in sophisticated data base for experimental investigations.
At last, some controversial observations in experimental studies concerning the kinetics of the electrophilic alkylation of the barbiturate anion are studied. To interpret the kinetic measurements, different alkylation pathways are analyzed with respect to their energetics. Further, the influence of microsolvation is demonstrated.
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Amass, Dorothy Gwendoline. "Block co-polymerization by transformation reactions". Thesis, Aston University, 1996. http://publications.aston.ac.uk/9679/.
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The aim of this study was to use the transformation of anionic to metathesis polymerization to produce block co-polymers of styrene-b-pentenylene using WC16/PStLi and WC16/PStLi/AlEtC12 catalyst systems. Analysis of the products using SEC and 1H and 13C NMR spectroscopy enabled mechanisms for metathesis initiation reactions to be proposed. The initial work involved preparation of the constituent homo-polymers. Solutions of polystyryllithium in cyclohexane were prepared and diluted so that the [PStLi]o < 2x10-3M. The dilution produced initial rapid decay of the active species, followed by slower spontaneous decay within a period of days. This was investigated using UV/visible spectrophotometry and the wavelength of maximum absorbance of the PStLi was found to change with the decay from an initial value of 328mn. to λmax of approximately 340nm. after 4-7 days. SEC analysis of solutions of polystyrene, using RI and UV/visible (set at 254nm.) detectors; showed the UV:RI peak area was constant for a range of polystyrene samples of different moleculor weight. Samples of polypentenylene were prepared and analysed using SEC. Unexpectedly the solutions showed an absorbance at 254nm. which had to be considered when this technique was used subsequently to analyse polymer samples to determine their styrene/pentenylene co-polymer composition. Cyclohexane was found to be a poor solvent for these ring-opening metathesis polymerizations of cyclopentene. Attempts to produce styrene-b-pentenylene block co-polymers, using a range of co-catalyst systems, were generally unsuccessful as the products were shown to be mainly homopolymers. The character of the polymers did suggest that several catalytic species are present in these systems and mechanisms have been suggested for the formation of initiating carbenes. Evidence of some low molecular weight product with co-polymer character has been obtained. Further investigation indicated that this is most likely to be ABA block copolymer, which led to a mechanism being proposed for the termination of the polymerization.
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Damiron, Denis. "Développement de nouvelles stratégies Robustes, Efficaces et Orthogonales pour l’élaboration et la fonctionnalisation de matériaux polymères". Thesis, Lyon 1, 2009. http://www.theses.fr/2009LYO10324.
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Les travaux réalisés au cours de cette thèse concernent trois différentes techniques de formulation innovantes qui ont été étudiées en tant que procédés robustes et efficaces pour l’élaboration de polymères fonctionnels à architecture contrôlée ou bien de films minces réticulés. La première stratégie exploite le caractère orthogonal de la click chemistry la plus connue: la cycloaddition catalysée par le cuivre(I) entre un azoture et un alcyne (CuAAC). Nous avons développé deux stratégies monotopes tandem complémentaires alliant CuAAC et Polymérisation Radicalaire Contrôlée (PRC) afin d’obtenir efficacement des architectures complexes en une seule étape. La deuxième stratégie concerne l’utilisation de la chimie thiol-ène en tant que click chemistry pour la fonctionnalisation de polymères et la réalisation d’architectures bien définies. Une série de polymères portant des insaturations ont été synthétisés par des techniques de polymérisation contrôlée dans le but d’étudier et de comparer l’efficacité des couplages thiol-ène initiés thermiquement ou hotochimiquement. Dans cette étude, l’orthogonalité de la chimie thiol-ène avec la CuAAC a également été étudiée. La troisième stratégie est inspirée des récentes techniques d’élaboration de matériaux réticulés/fonctionnalisés par couplage des azotures avec des insaturations. Nous avons développé une nouvelle stratégie d’élaboration efficace de matériaux massifs et de films minces de PDMS réticulés par utilisation d’un diazoture comme agent réticulant. Cette étude est réalisée en combinant des expertises en rhéologie, chimie et en couches mincesThis thesis focuses on three different and innovative techniques studied as efficient and robust processes to elaborate functional polymers with controlled architecture or crosslinked materials and thin films. The first strategy exploits the orthogonal property of a famous click chemistry: the Copper (I)-catalyzed Azide–Alkyne Cycloaddition (CuAAC). We developed two complementary strategies based on the one-pot tandem combination of CuAAC and Controlled Radical Polymerisation techniques (CRP) to efficiently elaborate complex polymer architectures. The second strategy is focused on the thiol-ene chemistry as a click chemistry and its use for the functionalisation of polymers in order to obtain well defined architectures. A series of alkenefunctional polymers were synthesized by controlled polymerization techniques in order to investigate and compare the efficiency and orthogonality of both photochemically and thermally initiated thiol-ene click coupling reactions. Orthogonality of thiol-ene chemistry with CuAAC was also studied. The third strategy is inspired of new processes developed to perform crosslinked/functionalised materials by azide-ene couplings. We investigate a new strategy for the elaboration of crosslinked PDMS in bulk or in thin films with the use of a diazide as coupling agent. This last study combines analyses in rheology, chemistry and in thin layer
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Heuken, Maria. "Fullerenhaltige Donor-Akzeptor-Blockcopolymere als Additive für organische Bulk-Heterojunction-Solarzellen". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-100244.
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Fullerenhaltige Bulk-Heterojunction-Solarzellen auf Polymerbasis zeigen derzeit eine geringe Langzeitstabilität, die unter anderem auf der Entmischung der Bulkphasen beruht. In dieser Arbeit wurden daher auf neuartige Weise Blockcopolymere entwickelt, die zur Stabilisierung der Phasen dienen können. Ausgehend von Poly-3-hexylthiophen-Makroinitiatoren wurde ein zweiter Block mit reaktivem Comonomer polymerisiert, das zur Anbindung von reinem Fullerens bzw. von Fullerenderivaten diente. Die fullerenfunktionalisierten Polymere wurden in Modell-Systeme eingemischt und zeigten erste Verbesserungen bezüglich der Phasenstabilisierung.
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Ding, Shijie. "Atom transfer radical polymerization". Laramie, Wyo. : University of Wyoming, 2006. http://proquest.umi.com/pqdweb?did=1225138911&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Shorter, Anthony John. "Use of enzymes in selected polymerization reactions". Thesis, University of Exeter, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390173.
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Pfeifer, Carmem Silvia Costa. "Parâmetros relacionados à cinética de reação e tensão de polimerização de compósitos restauradores". Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/23/23140/tde-10042008-062626/.
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Proposição: O objetivo deste estudo foi avaliar como a contração volumétrica (CV), o grau de conversão (GC), a taxa máxima de polimerização (RPmax) e a tensão de polimerização (TPmax) de dois compósitos experimentais são influenciados pela concentração de fotoiniciadores na matriz e pela irradiância aplicada na fotopolimerização. Material e métodos: Duas séries de monômeros foram formuladas, com partes iguais em peso dos seguintes monômeros: série B= Bis-GMA/ TEGDMA; série U= Bis-GMA/ UDMA / TEGDMA. Essas séries foram combinadas a três níveis de fotoiniciadores, num total de seis materiais experimentais, com a concentração em porcentagem de peso de uma amina terciária (EDMAB) e canforoquinona (CQ), respectivamente: alta (H)= 0,8 / 1,6; intermediária (M)= 0,4 / 0,8 e baixa (L)= 0,2 / 0,4. A todas as misturas, 75% e peso de vidro de estrôncio e 5% em peso de OX-50 (sílica coloidal) foram adicionados. O estudo foi dividido em três módulos: no primeiro, os seis compósitos foram testados quanto aos parâmetros descritos acima para a mesma dose de energia aplicada. No segundo, os mesmos materiais foram testados com a dose de energia ajustada de acordo com a concentração de fotoiniciadores de modo que todos os níveis atingissem graus de conversão semelhantes. No terceiro módulo, os materiais com a concentração \"M\" de fotoiniciadores foram submetidos a uma de três irradiâncias: 200, 400 ou 600 mW/cm2, com o tempo de exposição ajustado para que a dose de energia fosse mantida constante. CV foi registrada em um dilatômetro de mercúrio, GC foi avaliado através de FTIR, RPmax foi obtida através de um DSC 7 e a TP foi avaliada em um aparato de compliance controlado, descrito por Sakaguchi et al., 2004. Resultados: Em todos os módulos, não houve interação entre os fatores e assim, as médias foram agrupadas por série de monômeros e nível de fotoiniciadores (módulos 1 e 2) ou nível de irradiância (módulo 3). No módulo 1, as concentrações \"H\" e \"M\" apresentaram GC semelhante, ambas estatisticamente superiores à apresentada pelo grupo com o menor conteúdo de CQ/amina. A série U apresentou GC superior à da série B. RPmax aumentou significantemente com a concentração de fotoiniciadores entre cada um dos níveis estudados (p<0,001), e foi maior para a série U (p<0,05). O grupo de concentração \"H\" apresentou valores de TPmax maiores do que os grupos de concentração \"L\", enquanto que \"M\" apresentou valores de TPmax semelhantes aos dos outros dois (p<0,001). As séries B e U apresentaram TPmax equivalente (p>0,05). CV foi maior para \"L\", estatisticamente diferente das outras duas. A série B apresentou maior CV (p<0,05 para ambos os fatores). No módulo 2, o GC não foi influenciado pela concentração de fotoiniciadores (p>0,05). A série U apresentou maior GC comparado com a série B (p<0,001). RPmax aumentou com a concentração de fotoiniciadores entre cada um dos níveis estudados e foi maior para a série U (p<0,001 para ambos). TPmax não foi influenciada pela concentração de fotoiniciadores (p>0,05). A série B apresentou maior TPmax comparado com a série U (p<0,001). CV foi maior para \"L\", estatisticamente diferente das outras duas. A série B apresentou maiores valores de CV (p<0,001 para ambos os fatores). No módulo 3, GC variou significantemente apenas com a irradiância (p<0,001), sendo que os grupos de alta irradiância apresentaram valores estatisticamente mais baixos comparados aos níveis de irradiância médio e baixo. RPmax, aumentou com a irradiância e foi maior para a série U (p<0,001 para ambos). A série B apresentou valores de TPmax do que os da série U. CV não foi influenciada pela irradiância (p=0,442). A série B apresentou CV estatisticamente maior que a série U (p<0,001). Conclusões: De maneira geral, podemos dizer que CV, GC e RPmax mostraram uma interação bastante complexa e, nas condições deste estudo, não foi possível determinar a contribuição relativa de cada um destes fatores no desenvolvimento da tensão de polimerização. No entanto, parece haver uma tendência de TPmax ser influenciada mais pronunciadamente pelo GC ou CV do que pela RPmax, como demonstrado nos módulos 2 e 3.Proposition: The objective of this study was to evaluate how the volumetric shrinkage (VS), degree of conversion (DC), maximum rate of reaction (RPmax), polymerization stress (PSmax) and maximum rate of stress development (RSmax) of two experimental composites are influenced by the photoinitiator concentration ([photo]) and by the irradiance. Methods and materials: Bis-GMA/TEGDMA (B series) and Bis GMA/UDMA/TEGDMA (U series) were mixed in equal parts in weight. A tertiary amine (EDMAB) and camphoroquinone (CQ), respectively, were added in three concentrations: high (H)= 0.8/1.6; intermediate (M)= 0.4/0.8 and low (L)= 0.2/0.4 (in wt%). In all mixtures, 80 wt% filler was added. The study was divided in three sections: I) composites were photoactivated with 13 J/cm2. II) radiant exposure was adjusted so that all [photo] would achieve similar DC. III) [photo] \"M\" materials were submitted to three irradiances: 200 (L), 400 (I) or 600 (H) mW/cm2, with exposure time adjusted to convey the same radiant exposure. VS was registered in a mercury dilatometer, DC was evaluated by FTIR spectroscopy, RPmax was obtained in a DSC 7 and PSmax was evaluated in a controlled compliance device, described previously (SAKAGUCHI; WILTBANK; MURCHISON, 2004a). Results: Because no interaction between the factors was observed (except for RSmax in sections I and III), means were pooled for monomer series and [photo] (sections I and II) or irradiance (section III). I) concentrations \"H\" and \"M\" presented similar DC, both statistically superior to \"L\" (p<0.001). U series presented higher DC compared to B series. RPmax increased significantly with photoinitiator concentration between each of the studied levels (p<0.001), and was higher for U series (p<0.05). VS was higher for \"L\", statistically different than the other two (p<0.05). B series presented higher VS (p<0.05). The group with \"H\" concentration presented PSmax higher than \"L\", while \"M\" presented values similar to both (p<0.001). B and U series presented equivalent PSmax (p=0.284). For B series, RSmax increased 100% between the lower e intermediate [photo]. For U series, this increase was only around 50%. II) DC was not influenced by [photo] (p=0.388). U series presented higher DC compared to B series (p<0.001). RPmax increased with [photo] between all studied levels and was higher for U series (p<0.001 for both). VS was higher for \"L\", statistically different from the other two (p<0.001). B series presented higher VS (p<0.001). PSmax was not influenced by the photoinitiator concentration (p=0119). B series presented higher PSmax compared to U series (p<0.001). RSmax increased with [photo] and was higher for U series (p<0.001). III) High irradiance groups presented statistically lower DC compared to the other irradiance levels (p<0.001). Monomer series did not influence DC (p=0.793). RPmax increased with the irradiance and was higher for U series (p<0.001 for both). VS was not influenced by the irradiance (p=0.442). B series presented VS statistically higher than U series (p<0.001). \"H\" groups presented higher PSmax compared to \"L\". \"M\" presented PSmax similar to both (p<0.001). B series presented PSmax higher than U series. While no difference in RSmax between irradiance leves was observed for B series, RSmax increased with the irradiance for U series. Conclusions: There seems to be a trend for PSmax to be influenced more markedly by DC or VS than by RPmax. However, VS, DC and RPmax showed a quite complex interaction and, in the conditions of the present study, it was not possible to determine the relative contribution of each of these factors on stress development.
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Vaněk, Martin. "Kinetika polymerací dentálních dimethakrylátových monomerů". Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2020. http://www.nusl.cz/ntk/nusl-414114.
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Aim of magister´s thesis was to study reaction kinetics of dental materials. Thesis was focused on dimethacrylate dental polymers, which are for example used for dental restoration, tooth repair and creating now teeth. First part of the thesis concentrates on influence of molar ratio on reation kinetics by addition of other monomer to polymer resin. Second part concentrates on influence of addition of additive silica on reaction kinetics of polymerization. Essential variables know as a polymerization ratio, conversion, gel point, glass transition temperature and storage modulus were studied. Firstly, polymerization ratio and conversion were observed by differential scanning calorimetry (DSC). Secondly rheology was observed by photoreometr. Finally, glass transition temperature and storage modulus were observed by dynamic mechanical analysis (DMA). Behaviour changes caused by addion of monomer or filler point out decrease of polymeration ratio and converstion. Same behaviour was observed by short exposure. In order to established network formation, values of gel point increased by higher concentration of monomer or filler. Glass transition temperature and storage modulus measured by DMA were evaluated. Those valuables had variable tendency due to monomer acting like filler at higher concentration. Also contradictory impact of different material conversion and filler concetration was discussed.
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Wang, Aileen Ruiling Zhu Shiping. "Diffusion-controlled atom transfer radical polymerization". *McMaster only, 2005.
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CAMPISTRON, GUILMET IRENE. "La reaction de metathese : synthese de molecules modeles et de diesters polydieniques, degradation controlee des polydienes". Le Mans, 1987. http://www.theses.fr/1987LEMA1021.
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Amelioration des processus de synthese des composes modeles des polydienes et d'oligomeres alpha , omega -bifonctionnels par reaction de cometatheses du cyclooctadiene-1,5 avec l'octene-4, le methyl-4 octene-4, l'hexadiene-1,5 et l'hexene-3 dioate de dimethyle
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Lentz, Nicolas. "Metallylene-sulfur compounds : synthesis, characterization and applications in coordination and catalysis". Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30274/document.
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Ce travail présente la synthèse de ligands mixtes germylène-sulfoxyde qui ont été utilisés en chimie de coordination avec plusieurs métaux de transitions et finalement appliqués en catalyse de transfert d'hydrogène. Une seconde partie de ce travail est axée sur la synthèse de nouveaux métallylènes stabilisés par un sulfonimidamide qui ont été appliqués en catalyse de polymérisation. Le premier chapitre présente l'état de l'art des germylènes avec leurs synthèses, modes de stabilisations et finalement leur chimie de coordination et leurs applications en catalyse. Les sulfoxydes seront aussi décrits pour leur application en tant que ligands hémilabiles. Le second chapitre décrit la synthèse de ligands germylène-α-sulfoxide avec une diversité structurale (cyclohexyle, tBu, tolyle..) et avec différents degrés d'oxydation du souffre (thioéther, sulfoxyde et sulfone). La chimie de coordination a permis la synthèse de complexes bis-germylène du groupe IV, bidentes du ruthénium ainsi que monodentes du ruthénium. Le troisième chapitre présente l'extension de la méthodologie à la formation de ligands germylène-β-sulfoxide. L'influence du groupement espaçant les deux entités sur la chimie de coordination a été étudiée et montre la formation de complexes bidentates du groupe IV. La coordination du ruthénium a mené à la surprenante synthèse d'un complexe bis-ruthénium caractérisé par diffraction des rayons X. Finalement, la nouvelle architecture a permis d'obtenir des complexes de nickel (0) dont une structure avec des ligands carbonyles permettant une comparaison TEP. Le chapitre quatre présente la synthèse de nouveaux ligands, analogues des amidinates, pour la stabilisation des métallylènes avec un atome central soufré. L'effet apporté sur les métallylènes par ces nouveaux ligands sulfonimidamides a été étudié par calcul DFT. Le dernier chapitre est centré sur l'application de plusieurs complexes de ruthénium en catalyse de transfert d'hydrogène avec plusieurs substrats carbonylés. L'utilisation de stannylènes stabilisés par des ligands sulfonimidamides a été étudiée en catalyse de polymérisation de la ε-caprolactoneThis work concerns the synthesis of mixed germylene-sulfoxide ligands that were involved in coordination chemistry with several transition metals and finally applied in hydrogen transfer catalysis. In a second part, the synthesis of new metallylenes stabilized by a sulfonimidamide group was develop, which were applied in polymerization catalysis. The first chapter is centered on the state of the art of germylenes with their synthesis, their stabilization and finally their coordination chemistry and applications in catalysis. Sulfoxides will also be described for their potential as hemilabile ligands. The second chapter describes the synthesis of germylene-α-sulfoxide ligands as structurally tunable structures (cyclohexyl, tBu, tolyl..) and with different oxidation states of the sulfur atom (thioether, sulfoxide and sulfone). The coordination chemistry led to the formation of bis-germylene group IV complexes, bidentate-ruthenium and monodentate ruthenium complexes. The third chapter shows the extension of the methodology to the formation of germylene-β-sulfoxide ligands. The influence of the spacer between the two entities on the coordination chemistry was studied and shows the formation of bidentate group IV complexes. Coordination to ruthenium led to obtain a surprising bis-ruthenium complex characterized by X-ray diffraction analysis. Finally, the novel architecture allowed to obtain two nickel (0) complexes, one of them including carbonyl ligands permitting a TEP comparison. The fourth chapter is centered on the synthesis of new ligands, analogue of amidinate substituents for metallylene stabilization with a central sulfur atom. The effect brought to the metallylene center by the sulfonimidamide was studied by DFT calculations. The last chapter concerns the application of several ruthenium complexes in hydrogen transfer reaction with various carbonyl compounds. The use of sulfonimidamide stannylenes was also investigated in polymerization catalysis of ε-caprolactone
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Hirota, Wilson Hideki. "Avaliação de técnicas calorimétricas aplicadas ao monitoramento de processos químicos". Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-22042010-150213/.
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A crescente demanda por produtos poliméricos com propriedades cada vez mais estritas tem forçado o desenvolvimento de técnicas de monitoramento em linha cada vez mais precisas e robustas. Infelizmente, grande parte das principais propriedades poliméricas não são quantificáveis em linha a partir das metodologias analíticas atualmente disponíveis e, portanto, na prática, as propriedades finais dos látices poliméricos são obtidas através da caracterização off line de amostras discretas coletadas do processo, resultando em um tempo de análise longo e indesejado para qualquer algoritmo de controle em tempo real. Por outro lado, como as reações de polimerização são altamente exotérmicas é possível quantificar continuamente a taxa de calor gerado pela reação a partir das medidas de temperatura e do balanço de energia que, por sua vez, pode ser usada para obter importantes informações acerca do estado do processo. Entretanto, esta técnica requer a atualização contínua do coeficiente global de troca térmica ao longo da reação, uma vez que este parâmetro está sujeito a variações temporais significativas. Portanto, o presente trabalho tem por objetivo analisar a viabilidade da aplicação conjunta dos conceitos da calorimetria e dos observadores não-lineares para a estimação dos estados de um processo químico. Para isso, serão analisadas duas reações químicas distintas: a) uma reação de hidrólise de anidrido acético, b) uma reação copolimerização em emulsão. Os resultados obtidos mostraram que essa metodologia é extremamente dependente dos parâmetros de sintonia do observador de estado, inviabilizando o seu uso para o monitoramento em linha de um processo químico. Por outro lado, a aplicação direta do balanço de energia para estimação do calor gerado pela reação, mostrou-se uma forma alternativa simples e viável para a estimação em tempo real dos estados de uma reação de polimerização.The increasing demand for the production of polymers with more tight properties has placed great emphasis on the development of accurate and robust online monitoring techniques of polymerization reactions. Unfortunately, most of the main characteristics are not measurable online from analytical methodologies currently available and, therefore, in practice, the final properties of polymer latexes are obtained through off line characterization of discrete samples collected from the process, resulting in measurement delay which is undesirable for real-time control. On the other hand, since most of the polymerization reactions are highly exothermic, it is possible to quantify continuously the heat release rate based on temperature measurements and energy balance equations that, in turn, can be used to infer valuable information about the state of process. However, this approach requires up-dating the value of the global heat exchange coefficient through reaction, once this parameter is subject to significant time variations. Therefore, this work aims to examine the feasibility of joint implementation of the concepts of reaction calorimetry and nonlinear state observers for estimation of the states of a chemical process. In order to do that, two distinct chemical reactions will be considered: a) a hydrolysis of acetic anhydride reaction, b) an emulsion copolymerization reaction. The results showed that this approach shows a strong dependence of the tuning parameters, preventing its use for online monitoring of a chemical process. On the other hand, applying the heat balance it is possible to infer continuously the heat release rate and the states of polymerization reactions.
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Zoller, Alexander. "Development and kinetic modeling of resins for advanced thermoplastic polymer composite materials". Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4728.
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L’objectif de cette thèse est de développer un matériau à base de polyméthacrylate de méthyle (PMMA) amorcé par une réaction redox à température ambiante pour produire des composites thermoplastiques. Plus particulièrement, notre travail a consisté à étudier le mécanisme d’amorçage afin d’améliorer la formulation de la résine en terme de cinétique de polymérisation. Afin d’atteindre cet objectif, les paramètres d’Arrhenius de la décomposition d’amorceur ont été déterminés et intégrés dans un modèle de simulation numérique décrivant la polymérisation du MMA à température ambiante développé à l’aide du logiciel PREDICI. Basé sur cette simulation, des différents paramètres ont été testés dans le but de diminuer le temps de polymérisation. En complément de la détermination des paramètres du système d’amorçage, une étude de copolymérisation avec un grand nombre de comonomères a été effectuée. Cette étude a conduit à l’identification d’un monomère permettant d’accélérer la vitesse de polymérisation : le méthacrylate d’acetoacetoxyethyle (AAEMA). Une étude cinétique de ce monomère a été réalisée avec l’identification du coefficient de la vitesse de propagation kp ainsi que les paramètres de copolymérisation avec MMA, rMMA et rAAEMA. Les paramètres cinétiques, qui ont été déterminés expérimentalement, ont été vérifiés par une simulation numérique de copolymérisation de MMA et AAEMAComposite materials are used for decades as high-performance materials in industry. Up to date these materials were based on non-recyclable thermoset polymers. Nowadays, environmental and economical restrictions enhance the development of recyclable composite materials. For answering that demand, research focuses on the development of recyclable thermoplastic polymer composites. Within this context, the work of this thesis focuses on the development of a material based on a poly(methyl methacrylate) (PMMA) resin initiated with a redox initiation system at room temperature in order to prepare thermoplastic composites. More precisely, our work consisted of studying this initiation system and to improve the kinetics of the resin formulation. For that purpose, the Arrhenius parameters of the initiator decomposition reaction were determined and implemented in a simulation model that describes the polymerization of MMA at room temperature. Based on the simulation carried out on the software PREDICI, several conditions were tested aiming in the decrease of the polymerization times. Besides investigating parameters concerning the initiation system, a copolymerization study, using a large variety of comonomers, was conducted. This study led to the identification of an interesting fast polymerizing methacrylate: acetoacetoxyethyl methacrylate (AAEMA). The kinetics of this monomer were studied including the determination of the propagation rate coefficient kp and the copolymerization parameters with MMA rMMA and rAAEMA. The determined kinetic parameters were finally verified by a copolymerization simulation of MMA and AAEMA
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RIBEIRO, MARCOS S. "Sistema calorimétrico e software para análise da polimerização de compostos de metacrilato de metila, pela variação da exotermia da reação". reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10583.
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Made available in DSpace on 2014-10-09T12:42:14Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:04:44Z (GMT). No. of bitstreams: 0
Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Serin, Spencer Christopher. "Synthesis, polymerization and reactions of enantiomerically pure phosphaalkenes". Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/58902.
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This thesis outlines the polymerization and novel reactivity of enantiomerically pure compounds featuring the relatively uncommon phosphaalkene moiety.
Chapter 1 introduces the chemistry of the phosphaalkene (Ar-P=CR₂) structural fragment. This motif is compared and contrasted to the established chemistry of C=N and C=C groups. Similarities and differences are highlighted by an examination of: (a) phosphaalkene synthesis, (b) phosphaalkene polymerization and (c) phosphaalkene-metal coordination.
Chapter 2 details the addition reactions of MeM (M = MgBr, Li) nucleophiles to enantiomerically pure phosphaalkene-oxazoline 1.10a [PhAk-Ox, MesP=CPh(CMe₂Ox)]. Of note, the reaction of MeMgBr and PhAk-Ox is highly diastereoselective and affords a new P-chiral phosphine oxazoline ligand.
Chapters 3 and 4 report the free radical initiated homo- and co-polymerizations (with styrene) of enantiomerically pure phosphaalkene-oxazolines 1.10a (Chapter 3) and 4.1a [MesP=CPh(3-C₆H₄Ox), Chapter 4]. The coordination of rhodium(I) to copolymers of 1.10a and styrene permits the isolation of novel macromolecular complexes. Additionally, polymers of 4.1a display unique spectroscopic signatures that permit the direct assignment of styrene-phosphaalkene linkages in the polymer backbone.
Chapters 5 and 6 highlight the coordination chemistry of phosphaalkenes. Chapter 5 discusses the syntheses of κ³(PNN)-copper(I) complexes featuring enantiomerically pure pyridine-bridged phosphaalkene-oxazoline 5.1a [ArP=CPh(2-C₅H₃N-6-Ox)]. Chapter 6 explores the insertion of the P=C functional group into Pd–R bonds, permitting the synthesis of novel phosphapalladacyclopropanes (6.1a-b) and palladium(II) complexes featuring 1,2-dihydropyridinato donors (6.3 and 6.4).
Chapter 7 provides perspective for the work contained within this thesis.Science, Faculty of
Chemistry, Department of
Graduate
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Dorobantu, Ioana-Miruna. "Vinyl chloride polymerization in microdroplet reactor". Thesis, Toulouse, INPT, 2012. http://www.theses.fr/2012INPT0037/document.
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La polymérisation du chlorure de vinyle est une réaction très fréquente dans l’industrie des polymères, conduisant à l’obtention d’un matériau plastique très commun, connu sous le nom de PVC (polychlorure de vinyle). Ses applications concernent principalement l’industrie des constructions néanmoins d’autres domaines sont également touchés. La complexité de ce procédé de polymérisation est due à la nature toxique du monomère, à la maitrise du transfert de chaleur ou au maintien de l’agitation. Le control de ces variables de procédé influence de manière directe les caractéristiques finales du produit. Même si la polymérisation en suspension du chlorure de vinyle a été largement étudiée dans des réacteurs de type batch, il y a un manque de données au niveau de la cinétique et de la physicochimie d’une goutte de monomère pendant la réaction. L’objectif de ces travaux est de proposer un dispositif microstructuré permettant d’obtenir des gouttes monodisperses ayant un diamètre de 200 µm environ, chacune étant considérée comme un réacteur de polymérisation. Une fois identifiés les verrous liés au système eau/chlorure de vinyle en microréacteur, la réaction de polymérisation a été décrite de manière qualitative par visualisation des gouttes/grains de polymère. Des mesures Raman non-invasives en temps réel ont été réalisées sur une goutte immobile de chlorure de vinyle, cela permettant d’accéder aux valeurs des constantes cinétiques. Un modèle théorique en bon accord avec les résultats expérimentaux a été proposé afin de simuler le degré de conversion de la réaction. Les caractéristiques morphologiques des grains de PVC obtenus en microréacteur présentent des particularités intéressantes en termes d’agglomération des particules primaires ou porositéVinyl chloride suspension polymerization is a common reaction in polymer industry allowing to obtain one of the world wide most used plastics, known as PVC (polyvinyl chloride). Its applications involve mostly the construction industry but other domains are also concerned. This polymerization process is highly complex due to the toxic nature of the monomer, the good manage of heat transfer and agitation. The control of these process variables directly impacts the characteristics of the final product. Even though the suspension polymerization of vinyl chloride has been extensively studied in batch reactors, there is a lack of data regarding the kinetics or the physicochemistry of a single monomer droplet during the reactions. The aim of this present work is to propose a microstructured device which enables obtaining monodisperse droplets within 200 µm in diameter, each one being considered as a polymerization reactor. After a good acknowledgement of the vinyl chloride/water system in microchannel the polymerization reaction was qualitatively described by means of droplet/polymer grain visualization. Real-time non-invasive Raman measurement has been performed on stationary vinyl chloride monomer droplets and has provided values of kinetic constants. A theoretical model was proposed, simulating the reaction conversion in good agreement with the experimental values. The morphologic characteristics of the PVC grains obtained in microreactor presented interesting features in terms of primary particle agglomeration or porosity
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NICOL, PASCAL. "Etude comparee des polymerisations cationiques des cyclosiloxanes par des amorceurs protoniques et non protoniques". Paris 6, 1987. http://www.theses.fr/1987PA066711.
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Polymerisation de l'hexamethylcyclosiloxane amorcee par des complexes d'association entre un acide de lewis et un chlorure d'acide, donnant les memes produits que la polymerisation amorcee par l'acide trifluorosulfonique. Formation dans les 2 cas d'un haut polymere par un mecanisme de propagation en chaine via un nombre constant de macromolecules lineaires. Discussion des mecanismes globaux possibles
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Meziane, Driss. "Etude de la polymérisation des alcynes amorcée par un dérivé alkylidène du tungstène". Paris 13, 1986. http://www.theses.fr/1986PA132002.
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Debord, Justin. "Synthesis, characterization and properties of bioconjugated hydrogel nanoparticles". Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-06072004-131123/unrestricted/debord%5Fjustin%5F200405%5Fphd.pdf.
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Tupe, Ravindra Radhakisan. "Tubular reactor for liquid-phase propylene polymerization". Enschede : University of Twente [Host], 2006. http://doc.utwente.nl/56177.
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Kwalik, Kristina Mary. "Adaptive control of a continuous polymerization reactor". Thesis, Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/21474.
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