Cmc of PMMA-block-PDMAEMA measured by NPN fluorescence

Souza, Valdomiro Vagner de; Noronha, Maria Luiza de Carvalho; Almeida, Fabrini Luiz Alves; Prado, César Augusto Ribeiro; Florenzano, Fabio Herbst

doi:10.1007/s00289-011-0508-x

Cited by 12 publications

(16 citation statements)

References 22 publications

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“…Controlled radical polymerization has been utilized to prepare PMMA‐ block ‐PDMAEMA‐ block ‐PMMA brushes . Also, RAFT was used to synthesize PDMAEMA based block copolymers with methacrylate monomers , …”

Section: Introductionmentioning

confidence: 99%

Synthesis, characterization and thermal degradation of dual temperature‐ and pH‐sensitive RAFT‐made copolymers of N,N‐(dimethylamino)ethyl methacrylate and methyl methacrylate

Roy

Bauri

Pal

et al. 2012

Polymer International

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Poly{[(N,N‐(dimethylamino)ethyl methacrylate]‐co‐(methyl methacrylate)} copolymers of various compositions were synthesized by reversible addition‐fragmentation chain transfer (RAFT) polymerization at 70 °C in N,N‐dimethylformamide. The polymer molecular weights and molecular weight distributions were obtained from size exclusion chromatography, and they indicated the controlled nature of the RAFT polymerizations; the polydispersity indices are in the range 1.1–1.3. The reactivity ratios of N,N‐(dimethylamino)ethyl methacrylate (DMAEMA) and methyl methacrylate (MMA) (rDMAEMA = 0.925 and rMMA = 0.854) were computed by the extended Kelen–Tüdös method at high conversions, using compositions obtained from 1H NMR. The pH‐ and temperature‐sensitive behaviour were studied in aqueous solution to confirm dual responsiveness of these copolymers. The thermal properties of the copolymers with various compositions were investigated by differential scanning calorimetry and thermogravimetric analysis. The kinetics of thermal degradation were determined by Friedmann and Chang techniques to evaluate various parameters such as the activation energy, the order and the frequency factor. © 2012 Society of Chemical Industry

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Section: Introductionmentioning

confidence: 99%

Synthesis, characterization and thermal degradation of dual temperature‐ and pH‐sensitive RAFT‐made copolymers of N,N‐(dimethylamino)ethyl methacrylate and methyl methacrylate

Roy

Bauri

Pal

et al. 2012

Polymer International

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“…The copolymer PMMA-b-PDMAEMA obtained by RAFT used in this work. The indexes "m" and "n" were estimated by GPC as being 53 and 381 in average, respectively [17] . anion (in that case chloride and perchlorate) concentration changes the LCST values.…”

Section: Resultsmentioning

confidence: 99%

“…The pKa of the amine group is around 8 [18] , so that, at neutral and acid pH´s, most of the nitrogen is protonated in aqueous solution. Under such conditions and above the critical micelle concentration (~10 -3 g L -1 ) [17] the copolymers are aggregated (DLS data not shown) into positive charged micelles [6] .…”

Section: Methodsmentioning

confidence: 99%

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Urea decreases specific ion effects on the LCST of PMMA-block-PDMAEMA aggregates

Souza

Florenzano

2014

Polímeros

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Urea is a well-known additive used as a mild protein denaturant. The effect of urea on proteins, micellar systems and other colloids is still under debate. In particular, urea has shown interesting effects on the ion binding in systems like charged micelles, vesicles or Langmuir-Blodgett films. The urea effect on polymeric aggregates in water is still an open field. For instance, the additive may affect properties such as cmc, LCST, UCST and others. In particular, LCST is a property that can be very convenient for designing smart systems that respond to temperature. Previous studies have indicated that the LCST of positive charged copolymers aggregates based on poly[N-dimethyl(ethylamine methacrylate)], PDMAEMA, can be nicely modulated by anions in aqueous solution and such phenomenon depends on the nature of the anion present. In this work, it has been demonstrated that urea also affects the LCST of PMMAblock-PDMAEMA aggregates in aqueous solution. In addition, in the presence of high concentrations of the additive, the specific behavior of the anions is lost, supporting the general mechanism of urea reducing the differences on ion binding to surfaces in aqueous solutions. To the best of our knowledge, this is the first time those phenomena are shown in polymer micelles.

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“…Porém, somente em 2007 [25] é que foram publicadas de fato as primeiras pesquisas experimentais envolvendo pesquisadores brasileiros com o tema. Outros artigos sobre polimerização RAFT, envolvendo a participação de pesquisadores brasileiros, vêm sendo publicados até a presente data [23,[26][27][28][29][30][31][32][33] , sendo algumas dessas totalmente desenvolvidas em universidades brasileiras [29,[31][32][33] . O tema da polimerização RAFT também já foi abordado recentemente, de forma resumida, em outras publicações nacionais [27] .…”

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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Cmc of PMMA-block-PDMAEMA measured by NPN fluorescence

Cited by 12 publications

References 22 publications

Synthesis, characterization and thermal degradation of dual temperature‐ and pH‐sensitive RAFT‐made copolymers of N,N‐(dimethylamino)ethyl methacrylate and methyl methacrylate

Synthesis, characterization and thermal degradation of dual temperature‐ and pH‐sensitive RAFT‐made copolymers of N,N‐(dimethylamino)ethyl methacrylate and methyl methacrylate

Urea decreases specific ion effects on the LCST of PMMA-block-PDMAEMA aggregates

Polimerização RAFT em Miniemulsão

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