A Comparison of Reaction Mechanisms for Reversible Addition‐Fragmentation Chain Transfer Polymerization Using Modeling Tools

Pallares, Jhonatan; Jaramillo‐Soto, Gabriel; Flores‐Cataño, Citlalli; Lima, Eduardo Vivaldo; Lona, Liliane Maria Ferrareso; Penlidis, Alexander

doi:10.1080/10601320600814614

Cited by 39 publications

(50 citation statements)

References 23 publications

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“…It is clearly observed that increasing the amount of RAFT controller, at a fixed initiator concentration, causes the polymerization rate to decrease (Figure 1a), the number-average molecular weight, M n , to decrease (Figure 1b), and the polydispersity index (PDI) to also decrease (Figure 1c). This ''retardation effect'' type of behavior is typical of RAFT polymerization systems, and has been described and explained in the literature (see, for instance, Pallares et al [26] and references therein). It is observed, however, that at the simulated conditions (as in Table 3 and 4), the PDI never reached values lower than 1.4, and at high monomer conversions, PDI increased sharply up to values close to 3, and even higher.…”

Section: Reaction Phasementioning

confidence: 91%

“…This behavior is also consistent with that observed for RAFT batch polymerization systems at low pressures. [26] The temperature effect in the system comes from the Arrhenius dependence of the kinetic rate constants, but also from the temperature dependence of the reagent densities, particularly of the CO 2 density.…”

Section: S1mentioning

confidence: 99%

“…[26] The reactions involving polymer molecules in the dispersed phase (bimolecular radical termination, monomer propagation, addition to RAFT agent or dormant polymer, and fragmentation of one-or two-arm adducts) can become diffusion-controlled (DC). The possibility of DC-reactions was included in the model by using freevolume theory, as shown in Equation (9).…”

Section: Polymerization Kineticsmentioning

confidence: 99%

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Simulation of RAFT Dispersion Polymerization in Supercritical Carbon Dioxide

Jaramillo‐Soto

Castellanos-Cárdenas

García-Morán

et al. 2008

Macro Theory & Simulations

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The RAFT radical polymerization of vinyl monomers in supercritical carbon dioxide was modeled using the Predici® simulation package. The sensitivity of polymerization responses on formulation and process variables was analyzed. The simulations were carried out using kinetic and physical parameters corresponding to the polymerization of methyl methacrylate in supercritical carbon dioxide, using AIBN as initiator, at 65 °C and 200 bar, and using values of the addition and fragmentation kinetic rate constants of a “typical” RAFT agent, as reference conditions. This is the first report in the literature addressing the modeling or simulation of RAFT polymerization in supercritical carbon dioxide.magnified image

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Section: Reaction Phasementioning

confidence: 91%

Section: S1mentioning

confidence: 99%

Section: Polymerization Kineticsmentioning

confidence: 99%

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Simulation of RAFT Dispersion Polymerization in Supercritical Carbon Dioxide

Jaramillo‐Soto

Castellanos-Cárdenas

García-Morán

et al. 2008

Macro Theory & Simulations

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“…This temperature effect can of course be explained by the effect of T on the individual rate constants of the reactions involved in the RAFT polymerization scheme, which has been studied in detail for conventional (in the absence of CO 2 ) systems. [33] …”

Section: Effect Of Temperaturementioning

confidence: 97%

Effect of Stabilizer Concentration, Pressure and Temperature on Polymerization Rate and Molecular Weight Development in RAFT Polymerization of MMA in scCO₂

Jaramillo‐Soto

García-Morán

Vivaldo‐Lima

2010

Macromolecular Symposia

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Summary: An experimental study on the effect of stabilizer concentration, pressure (100 to 500 bar), and temperature (65 to 85 8C) on polymerization rate and molecular weight development in the reversible addition-fragmentation chain transfer (RAFT) polymerization of methyl methacrylate (MMA) in supercritical carbon dioxide (scCO 2 ) is presented. AIBN was used as initiator, S-Thiobenzoyl thioglycolic acid as RAFT agent, and Krytox 1 257 FSL as stabilizer. It was observed that the polymerization proceeded in a controlled manner. High conversions can be reached in reasonable times. Fairly low polydispersities (around 1.2) are possible if either pressure or temperature are increased, but better results are obtained if the polymerization proceeds at the upper temperature value of 85 8C.

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“…Desde a sua descrição, feita há mais de dez anos na literatura científica [18] , a técnica de polimerização RAFT tem despertado interesse de alguns pesquisadores brasileiros, que dedicaram esforços para explorar essa nova técnica de polimerização. A primeira publicação sobre a técnica de polimerização RAFT envolvendo pesquisadores brasileiros foi publicada em 2006 [24] , embora esta tenha sido uma pesquisa mais voltada para a área de simulação. Porém, somente em 2007 [25] é que foram publicadas de fato as primeiras pesquisas experimentais envolvendo pesquisadores brasileiros com o tema.…”

Section: A Técnica De Polimerização Raftunclassified

Polimerização RAFT em Miniemulsão

Oliveira¹,

Nele²,

Pinto³

2013

Polímeros

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Resumo: Dentre as diversas técnicas para obter polímeros de maneira controlada, a técnica de Transferência Reversível de Cadeia por Adição-Fragmentação (RAFT) é tida como uma das mais versáteis, uma vez que é compatível com uma grande quantidade de monômeros, solventes, condições reacionais e sistemas de polimerização. Utilizando essa metodologia, é possível sintetizar polímeros com diversas arquiteturas e com excelente controle do tamanho das cadeias. Neste trabalho, é apresentada uma revisão da técnica de polimerização RAFT em sistemas de miniemulsão. As principais características da técnica de polimerização RAFT e uma ampla revisão dos estudos em miniemulsão são apresentadas, abrangendo mais de 152 referências. Também é abordado nesta revisão o uso da polimerização RAFT em miniemulsão para obtenção de polímeros para aplicações biotecnológicas. Palavras-chave: Polimerização, RAFT, miniemulsão, biotecnologia, nanopartículas. RAFT Polymerization in MiniemulsionsAbstract: Among the many techniques used to prepare polymers in a controlled manner, reversible addition fragmentation chain transfer polymerization (RAFT) is one of the most versatile, since this technique is compatible with a large number of monomers, solvents, reaction conditions and polymerization systems. Using this methodology, it is possible to synthesize polymers with a variety of architectures and with a high level of control of the molecular weight distribution. In this work, a review of RAFT polymerizations in miniemulsion systems is presented. The main characteristics of the RAFT polymerization technique and a comprehensive review of studies in miniemulsion are presented, comprising more than 152 references. The use of RAFT miniemulsion polymerizaton to obtain polymers for biotechnological applications is also discussed in detail. Keywords: Polymerization, RAFT, miniemulsion, biotechnology, nanoparticles. IntroduçãoO século XX foi particularmente impactante na sociedade contemporânea, especialmente com o advento da Química Moderna e seus inúmeros avanços, como a identificação das macromoléculas [1,2] e o desenvolvimento de inúmeras técnicas de polimerização [3] , que criaram um novo campo de pesquisa: a Ciência de Polímeros. Esse novo campo de pesquisa permitiu a criação de uma nova classe de materiais sintéticos, vulgarmente conhecidos como plásticos, que são empregados hoje nos mais variados tipos de aplicações, incluindo desde a confecção de embalagens para alimentos até dispositivos nanométricos usados no tratamento de doenças [4][5][6] . Os polímeros sintéticos são normalmente obtidos por reações de polimerização, que seguem usualmente os bem conhecidos mecanismos de polimerização em cadeia ou em etapas. Dentre os diversos processos disponíveis, as técnicas de polimerização via radicais livres (mecanismo em cadeia) são largamente empregados em plantas industriais para a síntese de polímeros. Isto se deve principalmente a algumas vantagens das reações via radicais livres frente a outros métodos de polimerização, sendo possível citar: (...

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A Comparison of Reaction Mechanisms for Reversible Addition‐Fragmentation Chain Transfer Polymerization Using Modeling Tools

Cited by 39 publications

References 23 publications

Simulation of RAFT Dispersion Polymerization in Supercritical Carbon Dioxide

Simulation of RAFT Dispersion Polymerization in Supercritical Carbon Dioxide

Effect of Stabilizer Concentration, Pressure and Temperature on Polymerization Rate and Molecular Weight Development in RAFT Polymerization of MMA in scCO₂

Polimerização RAFT em Miniemulsão

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A Comparison of Reaction Mechanisms for Reversible Addition‐Fragmentation Chain Transfer Polymerization Using Modeling Tools

Cited by 39 publications

References 23 publications

Simulation of RAFT Dispersion Polymerization in Supercritical Carbon Dioxide

Simulation of RAFT Dispersion Polymerization in Supercritical Carbon Dioxide

Effect of Stabilizer Concentration, Pressure and Temperature on Polymerization Rate and Molecular Weight Development in RAFT Polymerization of MMA in scCO2

Polimerização RAFT em Miniemulsão

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Effect of Stabilizer Concentration, Pressure and Temperature on Polymerization Rate and Molecular Weight Development in RAFT Polymerization of MMA in scCO₂