Living/controlled radical polymerization (L/CRP) techniques in aqueous based systems were studied. The main focus of this research was adapting an ATRP (atom transfer radical polymerization) to a microemulsion polymerization in order to form nano-size particles with low concentration of surfactant. In conventional microemulsion polymerization, the cationic surfactant cetyltrimethylammonium bromide (CTAB) was successfully employed with a low weight ratio of surfactant/monomer of 1:10 to produce polymer particles with mean diameters less than 40 nm. Poor control resulted when this microemulsion polymerization was used with reverse ATRP, but using acetone as a phase transfer agent improved the results. The AGET (activators generated by electron transfer) initiation technique was also employed in microemulsion ATRP. In this “two-step” procedure, a reducing agent, ascorbic acid, was used to reduce the higher oxidation state catalyst in situ during the first stage to initiate a microemulsion polymerization. Monomer was then continuously fed to the microemulsion ATRP to form the final polymer latex. In an effort to improve this microemulsion polymerization, factors such as the catalyst concentration, temperature, and surfactant concentration were studied. Two monomers, butyl acrylate (BA) and butyl methacrylate (BMA) were investigated. When BA was used, linear first-order kinetic plots and relatively narrow molecular weight distribution (Mw/Mn~1.5) were observed. The final latex had a particle size ~20 nm. When BMA was employed, very fast reaction rates were obtained, leading to poorly controlled polymerizations with quite high polydispersity (Mw/Mn~2). The two-step AGET ATRP procedure in microemulsion provides options for synthesizing polymer nano-particles with low concentration surfactant in aqueous dispersed media. / Thesis (Master, Chemical Engineering) -- Queen's University, 2008-01-25 11:28:58.816 / Supervisor Dr. Michael F. Cunningham; Queen's University

One of the most effective methods for precision polymer synthesis is controlled radical polymerization, in which atom transfer radical polymerization (ATRP) is an excellent example. A series of ferrocene derivatives were prepared and applied for polymerization of methyl methacrylate (MMA). Formulation by combination of the ferrocenyl ligands and coprous bromide could catalyze ATRP, of which the performance is strongly dependent on the substituents on the Cp rings as well as the reaction condition. The redox potentials of the ferrocene derivatives reveal that the lower E1/2, the better performance on ATRP. The results also showed that the molecular structures of the catalysts determined by X-ray crystallography also play an important role for the performance of the polymerization.

Atom transfer radical polymerization is a new and important living polymerization mechanism because it can produce many different polymers with controlled microstructures and novel properties. The commercialization of these new polymers will require detailed polymer reaction engineering investigations. Mathematical models are essential in this stage because they can summarize our knowledge on polymers made by ATRP and help us to find the optimum conditions for their synthesis. This thesis studies the polymerization kinetics of ATRP with mathematical models based on our own experimental work and experimental data published by other researchers. ATRP with both monofunctional and bifunctional initiators are considered. This is one of very few studies combining detailed mathematical models for polymerization kinetics and polymer microstructure and experimental results in the area of ATRP. Fundamental mathematical models were used to study the main features of ATRP. Population balances and the method of moments were used to predict polymer average properties, while Monte Carlo models were used to predict the complete microstructural distributions. This type of comparison between different modeling techniques is seldom done in the literature, even for other polymerization techniques, and can lead to a better understanding of polymerization mechanisms and mathematical modeling techniques. Since the discovery of ATRP, approximately ten years ago, little attention has been given to bifunctional initiators. This thesis tries to extend our knowledge on this important class of initiators. Comparison between monofunctional and bifunctional initiators, both through mathematical modeling and experimentally, showed that bifunctional initiators have some advantages over monofunctional initiators for ATRP. Polymers made with bifunctional initiators have narrow molecular weight distributions, higher molecular weight averages, and higher monomer conversion for the same polymerization time. In addition to homopolymerization studies, this thesis presents mathematical models for copolymerization with ATRP and for processes combining ATRP and coordination polymerization. These models describe the detailed microstructures of these copolymers and permit a better understanding of ATRP with its advantages and pitfalls. An interesting conclusion from these modeling studies in atom transfer radical copolymerization is that the Mayo-Lewis terminal model is applicable to ATRP and that the copolymer composition in ATRP is independent of the equilibrium constants (activation and deactivation). In order to develop and validate these mathematical models, we collected experimental data in our own laboratories and also used experimental data available in the literature. Our experimental work focused on the homopolymerization and copolymerization of styrene, because of the commercial importance of this monomer and also due to the relative simplicity of its polymerization. Experimental data collected from the literature covered the following systems: bulk homopolymerization of styrene, solution polymerization of styrene, solution polymerization of methyl methacrylate, bulk polymerization of n-butyl acrylate, bulk copolymerization of styrene and n-butyl acrylate. Different characterization techniques were used to determine polymer properties. Molecular weight and molecular weight distribution were measured using gel permeation chromatography (GPC); copolymer chemical composition was determined with nuclear magnetic resonance (NMR) and Fourier-transform infrared (FTIR). We have also done copolymerization with styrene and acrylonitrile (SAN) because it is one of the least understood ATRP system and also because its potential industrial importance. The ability to synthesize polymers with novel molecular architectures is one of the advantages of living polymerization techniques. In this thesis, we used ATRP to produce amphiphilic copolymers composed of polystyrene and polyethylene glycol methacrylate macromonomers. We have shown that ATRP can produce these very interesting polymers with two different types of macroinitiators.

Silica (inorganic)-g-polymer (organic) hybrid materials with a large variety of functionality have been studied intensively because of the improvement in their physical and chemical properties (e.g., thermal, mechanical, electrical, magnetic properties, etc.) with respect to conventional organic and inorganic materials. 1–3 This research work introduces a new strategy based on in situ formation of poly(methyl methacrylate) block copolymer grafted silica nanoparticles. The thesis is divided into two major parts. In the first part, the atom transfer radical polymerization (ATRP) method was used to synthesize poly(methyl methacrylate-b-trimethoxysilyl propyl methacrylate) (PMMA-b-PTMSPMA); and poly(methyl methacrylate-b-trimethoxysilyl propyl acrylate) (PMMA-b-PTMSPA) block copolymers. Gel permeation chromatography (GPC) was performed to determine the number-average molecular weight (Mn) and polydispersity index (Đ) of PMMA-b PTMSPMA and PMMA-b-PTMSPA. In addition, proton nuclear magnetic resonance spectroscopy (1H NMR) was used to confirm the successful synthesis of the above copolymers. In the second part, the copolymers were used to form silica nanoparticles grafted with poly(propyl methacrylate-b-methyl methacrylate) [silica-g-(PPMA-b PMMA)] and silica nanoparticles grafted with poly(propyl acrylate-b-methyl methacrylate) [silica-g-(PPA-b-PMMA)]. Fourier transform infrared spectroscopy (FT-IR) and 29Si solid-state NMR were performed to confirm the formation of silica-g-(PPMA-b PMMA) and silica-g-(PPA-b-PMMA). Additionally, thermogravimetric analysis (TGA) was performed to assess the thermal decomposition of silica-g-(PPMA-b-PMMA) and silica-g-(PPA-b-PMMA). Multiple microscopic techniques such as TEM, cryo-TEM, SEM, and AFM were used to study micellization of the silica-g-(PPMA-b-PMMA) and silica-g-(PPA-b-PMMA) in tetrahydrofuran (THF) and chloroform

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Orientador: Maria Isabel Felisberti / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-27T10:33:06Z (GMT). No. of bitstreams: 1 Almeida_Paulade_M.pdf: 6180977 bytes, checksum: f368e755fcabe313d658156fe84a828e (MD5) Previous issue date: 2015 / Resumo: Neste trabalho foram sintetizados copolímeros anfifílicos e em bloco baseados em metacrilato de sacarose (SMA) e nos metacrilatos de alquila (MAlq): metacrilato de etila (EMA), metacrilato de n-butila (BMA) e metacrilato de n-hexila (HMA), via polimerização radicalar por transferência de átomo (ATRP). Para tal, utilizou-se o sistema catalítico catalisador/desativador/iniciador/ligante constituído de CuBr/CuBr2/2,2,2-tribromoetanol/1,1,4,7,10,10-hexametiltrietilenotetramina. Este sistema catalítico é inédito para a polimerização do EMA, BMA e HMA e dos copolímeros. A polimerização dos MAlq pode ser considerada viva, pois seguiu cinética de polimerização de pseudo-primeira ordem, gerando-se polímeros com polidispersidade estreita (PDI<1,3), massa molar pré-determinada e funcionalizados. A constante de velocidade de polimerização segue a ordem kEMA>kBMA>kHMA, ordem inversa do relatado para a polimerização radicalar livre. Os copolímeros inéditos [P(MAlq-b-SMA)] foram sintetizados, apresentando distribuição bimodal de massa molar, devido à copolimerização parcial dos macroiniciadores. Supõe-se que as cadeias dos macroiniciadores fiquem encapsuladas em agregados dos copolímeros durante a síntese, impossibilitando sua reação. As análises de GPC utilizando os solventes DMF e THF para um mesmo copolímero resultaram em massas molares diferindo entre si de cerca de 10 vezes, sugerindo que os copolímeros se agregam ou se auto-organizam em solução de DMF/THF a 5DMF:95THF (v/v). O caráter anfifílico foi comprovado pela estabilização de uma emulsão de água e benzeno. Demais propriedades físico-químicas dos copolímeros, tais como solubilidade, intumescimento, temperatura de transição vítrea, variação da capacidade calorífica e estabilidade térmica, são distintas a dos respectivos macroiniciadores, evidenciando as mudanças de propriedades dos polímeros devido à inserção de SMA / Abstract: In the present work, amphiphilic block copolymers based on sucrose methacrylate (SMA) and the alkyl methacrylates (MAlq): ethyl methacrylate (EMA), n-butyl methacrylate (BMA) and n-hexyl methacrylate (HMA), were synthesized by atom transfer radical polymerization (ATRP), employing the CuBr/CuBr2/2,2,2-tribromoethanol/1,1,4,7,10,10-hexamethyltriethylenetetramine as a catalyst/ deactivator/initiator/ligant system. This is a novel system for polymerizing EMA, BMA, HMA and their copolymers. This MAlq polymerization may be considered "living", because it followed a pseudo-first order kinetics, which resulted in polymer with narrow polidispersity (PDI<1,3), controlled molar mass and preserved chain end functionality. The apparent rate constants of the polymerization were found to follow the kEMA>kBMA>kHMA order, which is the opposite order reported in free radical polymerization. The novel copolymers [P(MAlq-b-SMA)] were synthesized, showing bimodal molar mass distribution, due to partial PMAlq copolymerization. Possibly, PMAlq chains are encapsulated into copolymer aggregates during polymerization, stopping its reaction. GPC analysis with DMF and THF as solvents differed in molar mass about 10 times, suggesting that copolymers can organize in a 5DMF:95THF (v/v) DMF/THF solution. The stabilization of a water and benzene emulsion proved the copolymers amphiphilicity. Other copolymer physical-chemistry properties, such as solubility, swelling, glass transition temperature, heat capacity change and thermal stability are different when compared to the macroinitiators, which is an evidence of change in polymer properties due to SMA monomer insertion. / Mestrado / Físico-Química / Mestra em Química

Atom transfer radical polymerization is a new and important living polymerization mechanism because it can produce many different polymers with controlled microstructures and novel properties. The commercialization of these new polymers will require detailed polymer reaction engineering investigations. Mathematical models are essential in this stage because they can summarize our knowledge on polymers made by ATRP and help us to find the optimum conditions for their synthesis. This thesis studies the polymerization kinetics of ATRP with mathematical models based on our own experimental work and experimental data published by other researchers. ATRP with both monofunctional and bifunctional initiators are considered. This is one of very few studies combining detailed mathematical models for polymerization kinetics and polymer microstructure and experimental results in the area of ATRP. Fundamental mathematical models were used to study the main features of ATRP. Population balances and the method of moments were used to predict polymer average properties, while Monte Carlo models were used to predict the complete microstructural distributions. This type of comparison between different modeling techniques is seldom done in the literature, even for other polymerization techniques, and can lead to a better understanding of polymerization mechanisms and mathematical modeling techniques. Since the discovery of ATRP, approximately ten years ago, little attention has been given to bifunctional initiators. This thesis tries to extend our knowledge on this important class of initiators. Comparison between monofunctional and bifunctional initiators, both through mathematical modeling and experimentally, showed that bifunctional initiators have some advantages over monofunctional initiators for ATRP. Polymers made with bifunctional initiators have narrow molecular weight distributions, higher molecular weight averages, and higher monomer conversion for the same polymerization time. In addition to homopolymerization studies, this thesis presents mathematical models for copolymerization with ATRP and for processes combining ATRP and coordination polymerization. These models describe the detailed microstructures of these copolymers and permit a better understanding of ATRP with its advantages and pitfalls. An interesting conclusion from these modeling studies in atom transfer radical copolymerization is that the Mayo-Lewis terminal model is applicable to ATRP and that the copolymer composition in ATRP is independent of the equilibrium constants (activation and deactivation). In order to develop and validate these mathematical models, we collected experimental data in our own laboratories and also used experimental data available in the literature. Our experimental work focused on the homopolymerization and copolymerization of styrene, because of the commercial importance of this monomer and also due to the relative simplicity of its polymerization. Experimental data collected from the literature covered the following systems: bulk homopolymerization of styrene, solution polymerization of styrene, solution polymerization of methyl methacrylate, bulk polymerization of n-butyl acrylate, bulk copolymerization of styrene and n-butyl acrylate. Different characterization techniques were used to determine polymer properties. Molecular weight and molecular weight distribution were measured using gel permeation chromatography (GPC); copolymer chemical composition was determined with nuclear magnetic resonance (NMR) and Fourier-transform infrared (FTIR). We have also done copolymerization with styrene and acrylonitrile (SAN) because it is one of the least understood ATRP system and also because its potential industrial importance. The ability to synthesize polymers with novel molecular architectures is one of the advantages of living polymerization techniques. In this thesis, we used ATRP to produce amphiphilic copolymers composed of polystyrene and polyethylene glycol methacrylate macromonomers. We have shown that ATRP can produce these very interesting polymers with two different types of macroinitiators.

Self-assembled polymer nanocomposites are a promising class of advanced materials with unique structures and tunable properties. Control over the spatial arrangement and ordering of the constituent material is essential to developing composites with defined morphologies and properties. Here I report the synthesis of poly(n-butyl acrylate-b-styrene) from the surface of functionalized montmorillonite clay (MMT) via activators regenerated by electron transfer (ARGET) atom transfer radical polymerization (ATRP). The application of ARGET ATRP to MMT surface-initiated polymerizations results in a robust and reproducible method for synthesizing well-defined tethered block copolymers. The chosen block copolymer architecture of the composite materials resembles that of a thermoplastic elastomer, with glassy PS domains sandwiching the rubbery PnBA domain, which is divided by the clay platelets. The structure was characterized by several techniques that examine the self-assembly and degree of clay exfoliation. Preliminary analysis of the material properties indicates elastomeric behavior. / text

A series of well-defined stimuli responsive water soluble [60]fullerene (C₆₀) containing polymers such as polyelectrolytes (polyacids and polybases), polyampholyte and polyzwitterionic polymers were synthesized using atom transfer radical polymerization. The aqueous solution properties of these polymers with respective external stimuli such as pH, temperature and salt were studied using potentiometric and conductivity titration, light transmittance, laser light scattering and transmission electron microscopic techniques. The influence of polymer concentration, temperature, pH and electrolyte on the hydrodynamic radius (Rh), radius of gyration (Rg) and aggregation number (Nagg) of the particles were investigated in detail to elucidate the morphology of the particles. The morphology of the aggregates was further confirmed by the TEM micrographs. The cytotoxicity of the pH responsive C₆₀ containing well-defined polymers (PAA-b-C₆₀, C₆₀-b-PAA-b-C₆₀ and PEO-b-PAA-b-C₆₀) was studied to confirm the suitability of these particles as potential drug delivery vehicles. The binding interaction between the anti-cancer drug (doxorubicin) and C₆₀ containing pH responsive polymers was studied using isothermal titration calorimetry, and the implication of the results will be discussed. / Singapore-MIT Alliance (SMA)

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