The use of living radical polymerization methods has shown significant potential to control grafting of polymers from inert polymeric substrates. The objective of this thesis is to create advanced substrates for use in combinatorial chemistry applications through the use of g-radiation as a radical source, and the use of RAFT, ATRP and RATRP living radical techniques to control grafting polymerization. The substrates grafted were polypropylene SynPhase lanterns from Mimotopes and are intended to be used as supports for combinatorial chemistry. ATRP was used to graft polymers to SynPhase lanterns using a technique where the lantern was functionalized by exposing the lanterns to gamma-radiation from a 60Co radiation source in the presence of carbon tetra-bromide, producing short chain polystyrene tethered bromine atoms, and also with CBr4 directly functionalizing the surface. Styrene was then grafted off these lanterns using ATRP. MMA was graft to the surface of SynPhase lanterns, using g-radiation initiated RATRP at room temperature. It was found that the addition of the thermal initiator, AIBN, successfully increased the concentration of radicals to a level where we could achieve proper control of the polymerization. RAFT was used to successfully control the grafting of styrene, acrylic acid and N,N???-dimethylacrylamide to polypropylene SynPhase Lanterns via a -initiated RAFT agent mediated free radical polymerization process using cumyl phenyldithioacetate and cumyl dithiobenzoate RAFT agents. Amphiphilic brush copolymers were produced with a novel combined RAFT and ATRP system. Polystyrene-co-poly(vinylbenzyl chloride) created using gamma-radiation and controlled with the RAFT agent PEPDA was used as a backbone. The VBC moieties were then used as initiator sites for the ATRP grafting of t-BA to give a P(t-BA) brush that was then hydrolyzed to produce a PAA brush polymer. FMOC loading tests were conducted on all these lanterns to assess their effectiveness as combinatorial chemistry supports. It was found that the loading could be controlled by adjusting the graft ratio of the lanterns and had a comparable loading to those commercially produced by Mimotopes.

The use of living radical polymerization methods has shown significant potential to control grafting of polymers from inert polymeric substrates. The objective of this thesis is to create advanced substrates for use in combinatorial chemistry applications through the use of g-radiation as a radical source, and the use of RAFT, ATRP and RATRP living radical techniques to control grafting polymerization. The substrates grafted were polypropylene SynPhase lanterns from Mimotopes and are intended to be used as supports for combinatorial chemistry. ATRP was used to graft polymers to SynPhase lanterns using a technique where the lantern was functionalized by exposing the lanterns to gamma-radiation from a 60Co radiation source in the presence of carbon tetra-bromide, producing short chain polystyrene tethered bromine atoms, and also with CBr4 directly functionalizing the surface. Styrene was then grafted off these lanterns using ATRP. MMA was graft to the surface of SynPhase lanterns, using g-radiation initiated RATRP at room temperature. It was found that the addition of the thermal initiator, AIBN, successfully increased the concentration of radicals to a level where we could achieve proper control of the polymerization. RAFT was used to successfully control the grafting of styrene, acrylic acid and N,N???-dimethylacrylamide to polypropylene SynPhase Lanterns via a -initiated RAFT agent mediated free radical polymerization process using cumyl phenyldithioacetate and cumyl dithiobenzoate RAFT agents. Amphiphilic brush copolymers were produced with a novel combined RAFT and ATRP system. Polystyrene-co-poly(vinylbenzyl chloride) created using gamma-radiation and controlled with the RAFT agent PEPDA was used as a backbone. The VBC moieties were then used as initiator sites for the ATRP grafting of t-BA to give a P(t-BA) brush that was then hydrolyzed to produce a PAA brush polymer. FMOC loading tests were conducted on all these lanterns to assess their effectiveness as combinatorial chemistry supports. It was found that the loading could be controlled by adjusting the graft ratio of the lanterns and had a comparable loading to those commercially produced by Mimotopes.

An experimental and modeling investigation of nitroxide-mediated radical polymerization (NMRP) of styrene using 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) as controller is presented. The objective was to examine the effect of temperature, controller to initiator molar ratio, and initiation mode on conversion, molecular weight and polydispersity development, and also to generate a source of reliable experimental data for parameter estimation and further model validation purposes. Polymerizations with a bimolecular initiator (Benzoyl Peroxide; BPO) were carried out at 120 and 130°C, with TEMPO/BPO molar ratios of 0.9 to 1.5. The effects of temperature and TEMPO/BPO ratio on polydispersity, molecular weight averages and conversion (rate) were studied. Results indicate that increasing temperature increases the rate of polymerization while the decrease in molecular weights is only slight. It was also observed that increasing the ratio of TEMPO/BPO decreased both the rate of polymerization and molecular weights. To investigate the contribution of thermal self-initiation in NMRP of styrene, thermal NMRP of styrene with TEMPO in the absence of initiator was carried out at 120 and 130°C. The results were compared with regular thermal polymerization of styrene and NMRP of styrene in the presence of BPO. It was observed that although the thermal polymerization of styrene can be controlled to some extent in the presence of TEMPO to provide lower polydispersity polystyrene, the polymerization was never as controlled as that obtained by a BPO initiated NMRP. Additional experiments were conducted with a unimolecular initiator and compared to the corresponding bimolecular system with the same level of nitroxide at 120°C, to gain additional insight on the advantages and disadvantages of each system. In addition, the importance of diffusion-controlled (DC) effects on the bimolecular NMRP of styrene was assessed experimentally by creating conditions where DC effects may be present from the outset. The results were corroborated by mathematical modeling and it was concluded that DC-effects are weak in the NMRP of styrene, even in the presence of “worst case scenario” conditions created. Finally, a mathematical (mechanistic) model based on a detailed reaction mechanism for bimolecular NMRP of styrene was presented and the predicted profiles of monomer conversion, molecular weight averages and polydispersity were compared with experimental data. Comparisons suggest that the present understanding of the reaction system is still inconclusive, either because of inaccuracy in values of kinetic rate constants used or because of some possible side reactions taking place in the polymerization system that are not included in the model. This was somewhat surprising, given that papers on controlled radical polymerization, and NMRP in particular, have clearly dominated the scientific polymer literature in the last fifteen years or so.

An experimental and modeling investigation of nitroxide-mediated radical polymerization (NMRP) of styrene using 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) as controller is presented. The objective was to examine the effect of temperature, controller to initiator molar ratio, and initiation mode on conversion, molecular weight and polydispersity development, and also to generate a source of reliable experimental data for parameter estimation and further model validation purposes. Polymerizations with a bimolecular initiator (Benzoyl Peroxide; BPO) were carried out at 120 and 130°C, with TEMPO/BPO molar ratios of 0.9 to 1.5. The effects of temperature and TEMPO/BPO ratio on polydispersity, molecular weight averages and conversion (rate) were studied. Results indicate that increasing temperature increases the rate of polymerization while the decrease in molecular weights is only slight. It was also observed that increasing the ratio of TEMPO/BPO decreased both the rate of polymerization and molecular weights. To investigate the contribution of thermal self-initiation in NMRP of styrene, thermal NMRP of styrene with TEMPO in the absence of initiator was carried out at 120 and 130°C. The results were compared with regular thermal polymerization of styrene and NMRP of styrene in the presence of BPO. It was observed that although the thermal polymerization of styrene can be controlled to some extent in the presence of TEMPO to provide lower polydispersity polystyrene, the polymerization was never as controlled as that obtained by a BPO initiated NMRP. Additional experiments were conducted with a unimolecular initiator and compared to the corresponding bimolecular system with the same level of nitroxide at 120°C, to gain additional insight on the advantages and disadvantages of each system. In addition, the importance of diffusion-controlled (DC) effects on the bimolecular NMRP of styrene was assessed experimentally by creating conditions where DC effects may be present from the outset. The results were corroborated by mathematical modeling and it was concluded that DC-effects are weak in the NMRP of styrene, even in the presence of “worst case scenario” conditions created. Finally, a mathematical (mechanistic) model based on a detailed reaction mechanism for bimolecular NMRP of styrene was presented and the predicted profiles of monomer conversion, molecular weight averages and polydispersity were compared with experimental data. Comparisons suggest that the present understanding of the reaction system is still inconclusive, either because of inaccuracy in values of kinetic rate constants used or because of some possible side reactions taking place in the polymerization system that are not included in the model. This was somewhat surprising, given that papers on controlled radical polymerization, and NMRP in particular, have clearly dominated the scientific polymer literature in the last fifteen years or so.

The speed of microelectronic devices is controlled by the size of the transistor gate. In order to create faster devices, the size of this transistor gate must shrink. Microlithography is the method used to define patterns in semiconductor devices, and it is optimized periodically to create smaller features. It is a subtractive process that relies on the selective removal of sections of a photosensitive polymeric film called photoresist. This photoresist is exposed to patterned ultraviolet radiation that changes the local solubility of the film and allows for the creation of relief patterns in the resist using a developing solvent. Decreasing the wavelength of the light used to expose the patterns is the primary method for decreasing the minimum feature size that can be printed by this process. There are a number of challenges associated with decreasing the exposure wavelength for conventional lithographic processes. First of all, the polymeric films must be transparent at the exposure wavelength in order to allow light to propagate through the entire thickness of the film. Secondly, there is a limit in the thickness of the photoresist films that can be used. This thickness limits the etch resistance of the film. In fact, the issues concerning etch resistance and transparency are generally in opposition. This makes designing photoresist platforms for future lithographic applications very difficult. Therefore, to overcome these limitations, we are developing an unconventional approach to microlithography. In our approach, entitled Surface Monolayer Initiated Polymerization, polymer structures are formed on a surface by polymerizing a monomer in a patterned fashion using a self-assembled monolayer that can be locally activated to initiate the reaction. This process has been demonstrated by creating patterned polystyrene films on native silicon dioxide surfaces. In these initial studies, it took more than one day to create features. This is unacceptable for a lithographic application. The kinetics of all the processes involved in making these patterned layers is described. Along with these rate constants, means of optimizing these rates are also presented. Additionally, the patterns grown in these initial studies exhibited poor uniformity. Methods of optimizing the patterns formed are also presented.

The successful production of a wide range of polymer latex products relies on the ability to control the rates of particle nucleation, growth and coagulation in order to maintain control over the particle size distribution (PSD). The development of advanced population balance models (PBMs) has simplified this task at the laboratory scale, but commercialization remains challenging as it is difficult to maintain control over the composition (i.e. spatial distributions of reactant concentration) of larger reactors. The objective of this thesis is to develop and test a combined Computational Fluid Dynamics (CFD) -PBM hybrid modeling framework. This hybrid modeling framework can be used to study the impact of changes in process scale on product quality, as measured by the PSD. The modeling framework developed herein differs from previously-published frameworks in that it uses information computed from species tracking simulations to divide the reactor into a series of interconnected zones, thereby ensuring the reactor is zoned based on a mixing metric. Subsequently, an emulsion polymerization model is solved on this relatively course grid in order to determine the time evolution of the PSD. Examination of shear rate profiles generated using CFD simulation (at varying reactor scales) suggests that, dependent on conditions, mechanically-induced coagulation cannot be neglected at either the laboratory or the commercial scale. However, the coagulation models that are formulated to measure the contributions of both types of coagulation simultaneously are either computationally expensive or inaccurate. For this reason the decision was made to utilize a DLVO-coagulation model in the framework. The second part of the thesis focused on modeling the controlled coagulation of high solids content latexes. POLY3D, a CFD code designed to model the flow of non-Newtonian fluids, was modified to communicate directly with a multi-compartment PBM. The hybrid framework was shown to be well-suited for modeling the controlled coagulation of high solid content latexes in the laminar regime. It was found that changing the size of the reactor affected the latex PSD obtained at the end of the process. In the third part of the thesis, the framework was adapted to work with Fluent, a commercial CFD code, in order to investigate the scale-up of a styrene emulsion polymerization reaction under isothermal conditions. The simulation results indicated that the ability to maintain good control of the PSD was inversely related to the reactor blend time. While the framework must be adapted further in order to model a wider range of polymerization processes, the value of the framework, in obtaining information that would otherwise be unavailable, was demonstrated. / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2012-05-01 07:09:08.362

No description available.

The use of living radical polymerization methods has shown significant potential to control grafting of polymers from inert polymeric substrates. The objective of this thesis is to create advanced substrates for use in combinatorial chemistry applications through the use of g-radiation as a radical source, and the use of RAFT, ATRP and RATRP living radical techniques to control grafting polymerization. The substrates grafted were polypropylene SynPhase lanterns from Mimotopes and are intended to be used as supports for combinatorial chemistry. ATRP was used to graft polymers to SynPhase lanterns using a technique where the lantern was functionalized by exposing the lanterns to gamma-radiation from a 60Co radiation source in the presence of carbon tetra-bromide, producing short chain polystyrene tethered bromine atoms, and also with CBr4 directly functionalizing the surface. Styrene was then grafted off these lanterns using ATRP. MMA was graft to the surface of SynPhase lanterns, using g-radiation initiated RATRP at room temperature. It was found that the addition of the thermal initiator, AIBN, successfully increased the concentration of radicals to a level where we could achieve proper control of the polymerization. RAFT was used to successfully control the grafting of styrene, acrylic acid and N,N???-dimethylacrylamide to polypropylene SynPhase Lanterns via a -initiated RAFT agent mediated free radical polymerization process using cumyl phenyldithioacetate and cumyl dithiobenzoate RAFT agents. Amphiphilic brush copolymers were produced with a novel combined RAFT and ATRP system. Polystyrene-co-poly(vinylbenzyl chloride) created using gamma-radiation and controlled with the RAFT agent PEPDA was used as a backbone. The VBC moieties were then used as initiator sites for the ATRP grafting of t-BA to give a P(t-BA) brush that was then hydrolyzed to produce a PAA brush polymer. FMOC loading tests were conducted on all these lanterns to assess their effectiveness as combinatorial chemistry supports. It was found that the loading could be controlled by adjusting the graft ratio of the lanterns and had a comparable loading to those commercially produced by Mimotopes.

Thesis (Ph.D)--Chemistry and Biochemistry, Georgia Institute of Technology, 2010. / Committee Chair: Weck, Marcus; Committee Member: Breedveld, Victor; Committee Member: Fahrni, Christoph; Committee Member: Kelly, Wendy; Committee Member: Lyon, L. Andrew. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Orientador: Liliane Maria Ferrareso Lona / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-24T00:08:56Z (GMT). No. of bitstreams: 1 Vieira_RonierikPioli_M.pdf: 2090320 bytes, checksum: 2a9ff9a429c08577f877080fe8c48d01 (MD5) Previous issue date: 2013 / Resumo: O processo de polimerização radicalar via transferência de átomo (ATRP) consiste numa das técnicas de polimerização radicalar controlada para a síntese de materiais com estruturas macromoleculares específicas. Através desta técnica, podem-se sintetizar homopolímeros monodispersos (baixos índices de polidispersidade), polímeros com funcionalidades terminais ou numa determinada posição da cadeia, o que permite produzir diversos copolímeros (em bloco, gradiente, aleatório etc), possibilitando agregar aos materiais propriedades requisitadas na indústria automobilística e aeroespacial, cosméticos, tintas e adesivos, além de possibilitar a produção de materiais para a liberação controlada de drogas e outras aplicações biomédicas. Apesar de todo este potencial relacionado à ATRP, a maioria das pesquisas encarrega-se de desenvolver novos materiais em escala laboratorial, deixando de lado a condução do processo em escalas comerciais. Neste contexto, o presente trabalho encarrega-se de desenvolver uma modelagem cinética do processo ATRP, juntamente com uma análise dos resultados da simulação para proporcionar aos leitores uma compreensão geral do processo, além de uma ferramenta matemática para futuros trabalhos de otimização e Scale up. A modelagem matemática foi desenvolvida utilizando balanços materiais, para prever perfis de concentração no reator, e o método dos momentos, para prever as massas molares e polidispersidades dos polímeros formados. Os modelos foram resolvidos numericamente em um programa computacional desenvolvido em linguagem Fortran e validados através de dados de literatura utilizando gráficos de dispersão. Por fim, uma análise paramétrica foi realizada com o intuito de estudar o comportamento do processo sob situações práticas, como por exemplo, alterações na constante de equilíbrio do processo (Keq), influência das razões iniciais de catalisador e iniciador sobre as propriedades finais, influência das terminações e transferências de cadeia, além da influência da temperatura de operação do reator / Abstract: Atom transfer radical polymerization (ATRP) is one of controlled radical polymerization techniques for the synthesis of materials with specific macromolecular structures. Using this technique, one can synthesize monodisperse homopolymer (low polydispersity index), end groups polymers or polymers with functionality in a particular position in the chain, which allows to produce different copolymers (block, gradient, random, etc.), allowing aggregate materials properties required in automotive and aerospace industry, cosmetics, paints and adhesives, and enable the production of materials for the controlled delivery of drugs and other biomedical applications. Despite this potential related to ATRP, most research is responsible for developing new materials on the laboratory scale, leaving aside the conduct of proceedings at commercial scales. In this context, this paper undertakes to develop a kinetic modeling of the ATRP process, together with an analysis of the simulation results to give readers a general understanding of the process, as well as a mathematical tool for future work on optimization and Scale up. A mathematical model was developed using material balances to predict concentration profiles in the reactor, and the method of moments to predict the molecular weight and polydispersities of the polymers formed. The models were solved numerically on a computer program developed in Fortran and validated through literature data using scatter plots. Finally, the parametric analysis was performed in order to study the behavior of chemical species in practical situations, such as changes in the process equilibrium constant (Keq), the influence of the initial ratio of catalyst and initiator on the final properties, influence terminations and chain transfers, beyond the influence of the operating temperature of the reactor / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química