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Artigos de revistas sobre o tema "RAFT/MADIX controlled radical polymerization"

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Autor: Grafiati

Publicado: 25 de maio de 2024

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1

Etchenausia, Laura, Abdel Khoukh, Elise Deniau Lejeune e Maud Save. "RAFT/MADIX emulsion copolymerization of vinyl acetate and N-vinylcaprolactam: towards waterborne physically crosslinked thermoresponsive particles". Polymer Chemistry 8, n.º 14 (2017): 2244–56. http://dx.doi.org/10.1039/c7py00221a.

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2

Seiler, Lucie, Julien Loiseau, Frédéric Leising, Pascal Boustingorry, Simon Harrisson e Mathias Destarac. "Acceleration and improved control of aqueous RAFT/MADIX polymerization of vinylphosphonic acid in the presence of alkali hydroxides". Polymer Chemistry 8, n.º 25 (2017): 3825–32. http://dx.doi.org/10.1039/c7py00747g.

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3

Destarac, Mathias, Juliette Ruchmann-Sternchuss, Eric Van Gramberen, Xavier Vila e Samir Z. Zard. "α-Amido Trifluoromethyl Xanthates: A New Class of RAFT/MADIX Agents". Molecules 29, n.º 10 (7 de maio de 2024): 2174. http://dx.doi.org/10.3390/molecules29102174.

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Xanthates have long been described as poor RAFT/MADIX agents for styrene polymerization. Through the determination of chain transfer constants to xanthates, this work demonstrated beneficial capto-dative substituent effects for the leaving group of a new series of α-amido trifluoromethyl xanthates, with the best effect observed with trifluoroacetyl group. The previously observed Z-group activation with a O-trifluoroethyl group compared to the O-ethyl counterpart was quantitatively established with Cex = 2.7 (3–4 fold increase) using the SEC peak resolution method. This study further confirmed the advantageous incorporation of trifluoromethyl substituents to activate xanthates in radical chain transfer processes and contributed to identify the most reactive xanthate reported to date for RAFT/MADIX polymerization of styrene.

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4

Wang, Pucheng, Jingwen Dai, Lei Liu, Qibao Dong, Hu Wang e Ruke Bai. "Synthesis and properties of a well-defined copolymer of chlorotrifluoroethylene and N-vinylpyrrolidone by xanthate-mediated radical copolymerization under 60Co γ-ray irradiation". Polym. Chem. 5, n.º 21 (2014): 6358–64. http://dx.doi.org/10.1039/c4py00902a.

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5

Zard, Samir Z. "The Genesis of the Reversible Radical Addition–Fragmentation–Transfer of Thiocarbonylthio Derivatives from the Barton–McCombie Deoxygenation: A Brief Account and Some Mechanistic Observations". Australian Journal of Chemistry 59, n.º 10 (2006): 663. http://dx.doi.org/10.1071/ch06263.

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The observations and reasoning leading to the discovery of the degenerative transfer of xanthates and related thiocarbonylthio derivatives are briefly described. A few synthetic applications are presented, and the consequences on the emergence of the RAFT and MADIX polymerization technologies as well as some mechanistic aspects are briefly discussed.

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6

Lou, Yu, Dong Jian Shi, Wei Fu Dong e Ming Qing Chen. "Synthesis and Self-Assemble Behavior of Block Copolymerization of Vinyl Acetate and N-Vinylacetamide". Advanced Materials Research 645 (janeiro de 2013): 10–14. http://dx.doi.org/10.4028/www.scientific.net/amr.645.10.

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Polymerizations of VAc was carried out using AIBN as the initiator and DIP as the MADIX agent precursor. Then, block copolymer PVAc-b-PNVA had been synthesized by RAFT radical polymerization in the presence of PVAc-DIP as macro CTA. The length of blocks could be tuned by changing the molar ratio of NVA and VAc. Block copolymer PVAc-b-PNVA self-assembled into micelles in solution, and underwent microphase separation in bulk state.

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7

Sütekin, S. Duygu, e Olgun Güven. "Radiation-induced controlled polymerization of acrylic acid by RAFT and RAFT-MADIX methods in protic solvents". Radiation Physics and Chemistry 142 (janeiro de 2018): 82–87. http://dx.doi.org/10.1016/j.radphyschem.2017.01.046.

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8

Lowe, A. B., e C. L. McCormick. "Homogeneous Controlled Free Radical Polymerization in Aqueous Media". Australian Journal of Chemistry 55, n.º 7 (2002): 367. http://dx.doi.org/10.1071/ch02053.

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The ability to conduct controlled radical polymerizations (CRP) in homogeneous aqueous media is discussed. Three main techniques, namely stable free radical polymerization (SFRP), with an emphasis on nitroxide-mediated polymerization (NMP), atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer polymerization (RAFT) are examined. No examples exist of homogeneous aqueous NMP polymerization, but mixed water/solvent systems are discussed with specific reference to the NMP of sodium 4-styrenesulfonate. Aqueous ATRP is possible, although monomer choice is limited to methacrylates and certain styrenics. Finally, homogeneous aqueous RAFT polymerizations are examined. We demonstrate the greater versatility of this technique, at least in terms of monomer variety, by discussing the controlled polymerization of charged and neutral acrylamido monomers and of a series of ionic styrenic monomers. Many of these monomers cannot/have not been polymerized by either NMP or ATRP.

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9

Wang, Zhongmin, Junpo He, Yuefei Tao, Liu Yang, Hongjin Jiang e Yuliang Yang. "Controlled Chain Branching by RAFT-Based Radical Polymerization". Macromolecules 36, n.º 20 (outubro de 2003): 7446–52. http://dx.doi.org/10.1021/ma025673b.

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10

Quiclet-Sire, Béatrice, e Samir Z. Zard. "Fun with radicals: Some new perspectives for organic synthesis". Pure and Applied Chemistry 83, n.º 3 (15 de outubro de 2010): 519–51. http://dx.doi.org/10.1351/pac-con-10-08-07.

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The degenerative radical addition-transfer of xanthates onto alkenes allows the rapid assembly of richly functionalized structures. Various families of open-chain, cyclic, and polycyclic compounds can thus be readily accessed. Furthermore, the process can be extended to the synthesis or modification of aromatic and heteroaromatic derivatives by exploiting the possibility of using peroxides both as initiators and stoichiometric oxidants. The modification of existing polymers and the controlled synthesis of block polymers by what is now known as the RAFT/MADIX (reversible addition–fragmentation transfer/macromolecular design by interchange of xanthate) process is described briefly.

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11

Wang, Lu, Wang e Bai. "A New Strategy for the Synthesis of Fluorinated Polyurethane". Polymers 11, n.º 9 (2 de setembro de 2019): 1440. http://dx.doi.org/10.3390/polym11091440.

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An alternating fluorinated copolymer based on chlorotrifluoroethylene (CTFE) and butyl vinyl ether (BVE) was synthesized by RAFT/MADIX living/controlled polymerization in the presence of S-benzyl O-ethyl dithiocarbonate (BEDTC). Then, using the obtained poly(CTFE-alt-BVE) as a macro chain transfer agent (macro-CTA), a block copolymer was prepared by chain extension polymerization of vinyl acetate (VAc). After a basic methanolysis process, the poly(vinyl acetate) (PVAc) block was transferred into poly(vinyl alcohol) (PVA). Finally, a novel fluorinated polyurethane with good surface properties due to the mobility of the flexible fluorinated polymer chains linked to the network was obtained via reaction of the copolymer bearing the blocks of PVA with isophorone diisocyanate (IPDI) as a cross-linking agent.

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12

Yusof, Noor Fadilah, Faizatul Shimal Mehamod e Faiz Bukhari Mohd Suah. "The effect of RAFT polymerization on the physical properties of thiamphenicol-imprinted polymer". E3S Web of Conferences 67 (2018): 03050. http://dx.doi.org/10.1051/e3sconf/20186703050.

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The necessity to overcome limitation of conventional free radical polymerization, technology has shifted the way to find an effective method for polymer synthesis, called controlled radical polymerization (CRP). One of the most studied controlled radical system is reversible addition-fragmentation chain transfer (RAFT) polymerization. The method relies on efficient chain-transfer processes which are mediated typically by thiocarbonyl-containing RAFT agents e.g., dithioesters. The presented study revealed the potential benefit in applying RAFT polymerization towards the synthesis of molecularly imprinted polymer for thiamphenicol. They were synthesized in monolithic form using methacrylic acid, ethylene glycol dimethacrylate, azobisisobutyronitrile and acetonitrile as a functional monomer, cross-linker, initiator and porogen, respectively. The surface morphology was studied by scanning electron microscopy (SEM), structural characterization by Fourier transformed infrared (FTIR) and pore structures of polymers produced were characterized by nitrogen sorption porosimetry. SEM analysis showed MIPs produced by RAFT have smoother surface while porosity analysis showed the specific surface area was slightly larger compared to conventional polymerization methods. However FTIR showed the same pattern of spectra produced due to the same co-monomers used in the production. The results upon the uses of RAFT polymerization enables the production of imprinted polymers enhanced the physical properties compared to conventional polymerization.

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13

Wang, Aileen R., e Shiping Zhu. "Effects of Diffusion-Controlled Radical Reactions on RAFT Polymerization". Macromolecular Theory and Simulations 12, n.º 23 (abril de 2003): 196–208. http://dx.doi.org/10.1002/mats.200390015.

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14

Prescott, Stuart W., Mathew J. Ballard, Ezio Rizzardo e Robert G. Gilbert. "Rate Optimization in Controlled Radical Emulsion Polymerization Using RAFT". Macromolecular Theory and Simulations 15, n.º 1 (16 de janeiro de 2006): 70–86. http://dx.doi.org/10.1002/mats.200500052.

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15

Lee, In-Hwan, Emre H. Discekici, Athina Anastasaki, Javier Read de Alaniz e Craig J. Hawker. "Controlled radical polymerization of vinyl ketones using visible light". Polymer Chemistry 8, n.º 21 (2017): 3351–56. http://dx.doi.org/10.1039/c7py00617a.

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Herein we report the photoinduced electron transfer–reversible addition–fragmentation chain transfer (PET-RAFT) polymerization of a range of vinyl ketone monomers including methyl, ethyl and phenyl derivatives, using Eosin Y as an organic photoredox catalyst and visible light.

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16

Hoff, Emily A., Brooks A. Abel, Chase A. Tretbar, Charles L. McCormick e Derek L. Patton. "Aqueous RAFT at pH zero: enabling controlled polymerization of unprotected acyl hydrazide methacrylamides". Polymer Chemistry 8, n.º 34 (2017): 4978–82. http://dx.doi.org/10.1039/c6py01563h.

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17

Avramovic, Milena, Lynne Katsikas, Branko Dunjic e Ivanka Popovic. "Reversible addition fragmentation chain transfer polymerization - RAFT". Chemical Industry 58, n.º 11 (2004): 514–20. http://dx.doi.org/10.2298/hemind0411514a.

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The fundamentals of controlled radical polymerization are presented in this review. The paper focuses on reversible addition fragmentation chain transfer (RAFT) polymerization. The mechanism and specifics of this type of polymerization are discussed, as are the possibilities of synthesizing complex macro-molecular structures. The synthesis and properties of RAFT agents, of the general structure Z-C(=S)-S-R, are presented.

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18

Chen, Mao, Honghong Gong e Yu Gu. "Controlled/Living Radical Polymerization of Semifluorinated (Meth)acrylates". Synlett 29, n.º 12 (18 de abril de 2018): 1543–51. http://dx.doi.org/10.1055/s-0036-1591974.

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Fluorinated polymers are important materials for applications in many areas. This article summarizes the development of controlled/living radical polymerization (CRP) of semifluorinated (meth)acrylates, and briefly introduces their reaction mechanisms. While the classical CRP such as atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer (RAFT) polymerization and nitroxide-mediated radical polymerization (NMP) have promoted the preparation of semifluorinated polymers with tailor-designed architectures, recent development of photo-CRP has led to unprecedented accuracy and monomer scope. We expect that synthetic advances will facilitate the engineering of advanced fluorinated materials with unique properties.1 Introduction2 Atom Transfer Radical Polymerization3 Reversible Addition-Fragmentation Chain Transfer Polymerization4 Nitroxide-Mediated Radical Polymerization5 Photo-CRP Mediated with Metal Complexes6 Metal-free Photo-CRP7 Conclusion

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19

Patil, Yogesh, e Bruno Ameduri. "First RAFT/MADIX radical copolymerization of tert-butyl 2-trifluoromethacrylate with vinylidene fluoride controlled by xanthate". Polymer Chemistry 4, n.º 9 (2013): 2783. http://dx.doi.org/10.1039/c3py21139h.

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20

Botha, Carlo, Wolfgang Weber, Helen Pfukwa e Harald Pasch. "Controlled Radical Polymerization Using a Novel Symmetrical Selenium RAFT Agent". Macromolecular Chemistry and Physics 215, n.º 17 (28 de julho de 2014): 1625–32. http://dx.doi.org/10.1002/macp.201400296.

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21

Moraes, John, Kohji Ohno, Guillaume Gody, Thomas Maschmeyer e Sébastien Perrier. "The synthesis of well-defined poly(vinylbenzyl chloride)-grafted nanoparticles via RAFT polymerization". Beilstein Journal of Organic Chemistry 9 (25 de junho de 2013): 1226–34. http://dx.doi.org/10.3762/bjoc.9.139.

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We describe the use of one of the most advanced radical polymerization techniques, the reversible addition fragmentation chain transfer (RAFT) process, to produce highly functional core–shell particles based on a silica core and a shell made of functional polymeric chains with very well controlled structure. The versatility of RAFT polymerization is illustrated by the control of the polymerization of vinylbenzyl chloride (VBC), a highly functional monomer, with the aim of designing silica core–poly(VBC) shell nanoparticles. Optimal conditions for the control of VBC polymerization by RAFT are first established, followed by the use of the “grafting from” method to yield polymeric brushes that form a well-defined shell surrounding the silica core. We obtain particles that are monodisperse in size, and we demonstrate that the exceptional control over their dimensions is achieved by careful tailoring the conditions of the radical polymerization.

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22

Li, Jiajia, Xiangqiang Pan, Na Li, Jian Zhu e Xiulin Zhu. "Photoinduced controlled radical polymerization of methyl acrylate and vinyl acetate by xanthate". Polymer Chemistry 9, n.º 21 (2018): 2897–904. http://dx.doi.org/10.1039/c8py00050f.

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23

Monteiro, M. J., R. Bussels, S. Beuermann e M. Buback. "High Pressure 'Living' Free-Radical Polymerization of Styrene in the Presence of RAFT". Australian Journal of Chemistry 55, n.º 7 (2002): 433. http://dx.doi.org/10.1071/ch02079.

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Reversible addition-fragmentation chain transfer (RAFT) polymerization of styrene was studied at high pressure, employing two dithioester RAFT agents with an isopropylcyano (5) and a cumyl (6) leaving group, respectively. The high-pressure reaction resulted in low polydispersity polymer. It was found that controlled polymerizations can be performed at increased pressures with a high degree of monomer conversion, which signifies that high-pressure polymerizations can be utilized for the production of higher molecular weight polystyrene of controlled microstructure. Retardation of styrene polymerization was also observed at high pressure in the presence of RAFT agents (5) and (6). It is postulated that the retarding potential of these two RAFT agents is associated with an intermediate radical termination mechanism. High-pressure free-radical polymerizations open the way to producing living polymers with high rates, and thus lower impurities such as 'dead' polymer that are formed through bimolecular termination reactions.

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24

Paulus, Renzo M., C. Remzi Becer, Richard Hoogenboom e Ulrich S. Schubert. "High Temperature Initiator-Free RAFT Polymerization of Methyl Methacrylate in a Microwave Reactor". Australian Journal of Chemistry 62, n.º 3 (2009): 254. http://dx.doi.org/10.1071/ch09064.

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The reversible addition–fragmentation chain transfer (RAFT) polymerization of methyl methacrylate (MMA) was investigated under microwave irradiation. At first, a comparison was made between microwave and thermal heating for the RAFT polymerization of MMA with azobis(isobutyronitrile) (AIBN) as initiator and 2-cyano-2-butyldithiobenzoate (CBDB) as RAFT agent, revealing comparable polymerization kinetics indicating the absence of non-thermal microwave effects. Second, the CBDB-mediated RAFT polymerization of MMA was investigated at high temperatures (120°C, 150°C, and 180°C, respectively) in the absence of a radical initiator, showing a linear increase of the molar masses with conversion. The polydispersity indices remained below 1.5 up to 25% MMA conversion at 120°C and 150°C, indicating a controlled polymerization. This control over the polymerization was confirmed by the ability to control the molar masses by the concentration of RAFT agent.

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25

Ge, Hao, Wencheng Shi, Chen He, Anchao Feng e San H. Thang. "Star-Shaped Thermoplastic Elastomers Prepared via RAFT Polymerization". Polymers 15, n.º 9 (23 de abril de 2023): 2002. http://dx.doi.org/10.3390/polym15092002.

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Styrene-based thermoplastic elastomers (TPEs) demonstrate excellent overall performance and account for the largest industrial output. The traditional methods of preparation styrene-based thermoplastic elastomers mainly focused on anionic polymerization, and strict equipment conditions were required. In recent years, controlled/living radical polymerization (CRP) has developed rapidly, enabling the synthesis of polymers with various complex topologies while controlling their molecular weight. Herein, a series of core crosslinked star-shaped poly(styrene-b-isoprene-b-styrene)s (SISs) was synthesized for the first time via reversible addition–fragmentation chain transfer (RAFT) polymerization. Meanwhile, linear triblock SISs with a similar molecular weight were synthesized as a control. We achieved not only the controlled/living radical polymerization of isoprene but also investigated the factors influencing the star-forming process. By testing the mechanical and thermal properties and characterizing the microscopic fractional phase structure, we found that both the linear and star-shaped SISs possessed good tensile properties and a certain phase separation structure, demonstrating the characteristics of thermoplastic elastomers.

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26

Quan, Qinzhi, Honghong Gong e Mao Chen. "Preparation of semifluorinated poly(meth)acrylates by improved photo-controlled radical polymerization without the use of a fluorinated RAFT agent: facilitating surface fabrication with fluorinated materials". Polymer Chemistry 9, n.º 30 (2018): 4161–71. http://dx.doi.org/10.1039/c8py00990b.

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27

Kwak, Yungwan, Renaud Nicolaÿ e Krzysztof Matyjaszewski. "Synergistic Interaction Between ATRP and RAFT: Taking the Best of Each World". Australian Journal of Chemistry 62, n.º 11 (2009): 1384. http://dx.doi.org/10.1071/ch09230.

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This review covers recent developments on the combination of atom transfer radical polymerization (ATRP) and reversible addition–fragmentation chain transfer (RAFT) polymerization to produce well controlled (co)polymers. This review discusses the relative reactivity of the R group in ATRP and RAFT, provides a comparison of dithiocarbamate (DC), trithiocarbonate (TTC), dithioester (DTE), and xanthate versus bromine or chlorine, and an optimization of catalyst/ligand selection. The level of control in iniferter polymerization with DC was greatly improved by the addition of a copper complex. New TTC inifers with bromopropionate and bromoisobutyrate groups have been prepared to conduct, concurrently or sequentially, ATRP from Br-end groups, ATRP from the TTC moiety, and RAFT polymerization from the TTC moiety, depending on the combination of monomer and catalyst employed in the reaction. The use of concurrent ATRP/RAFT (or copper-catalyzed RAFT polymerization or ATRP with dithioester leaving groups), resulted in improved control over the synthesis of homo- and block (co)polymers and allowed preparation of well-defined high-molecular-weight polymers exceeding 1 million. Block copolymers that could not be prepared previously have been synthesized by sequential ATRP and RAFT polymerization using a bromoxanthate inifer. A simple, versatile, and one-step method involving atom-transfer radical addition–fragmentation (ATRAF) for the preparation of various chain transfer agents (including DC, DTE, and xanthate) in high purity is discussed and a one-pot, two-step polymerization starting with a RAFT agent synthesized by ATRAF, followed by polymerization, is demonstrated.

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28

Bayburdov, Telman A., e Sergei L. Shmakov. "Modern methods of controlled radical polymerization for obtaining branched polymers of acrylamide, acrylic acid and (met)acrylates". Izvestiya of Saratov University. Chemistry. Biology. Ecology 22, n.º 3 (22 de setembro de 2022): 251–61. http://dx.doi.org/10.18500/1816-9775-2022-22-3-251-261.

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A search and analysis has been carried out of English-language 2005–2020 scientific literature devoted to methods of obtaining branched (co)polymers of acrylamide, acrylic acid and (met)acrylates in order to obtain novel materials with valuable properties. It has been found that modern methods of controlled radical polymerization are mainly used for this purpose, namely, atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer polymerization (RAFT) and group transfer polymerization (GTP). In most cases, original synthesized compounds were the chain transfer agents in RAFT. Depending on the order of synthesis, a distinction is made between the “core–arms” and “arms–core” approaches. The prospects of using branched polymers of acrylamide, acrylic acid and (met)acrylates for bioconjugation, surface immobilization, tissue engineering, oil production enhancement, and flocculation are estimated.

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29

D'Agosto, Franck, e Christophe Boisson. "A RAFT Analogue Olefin Polymerization Technique Using Coordination Chemistry". Australian Journal of Chemistry 63, n.º 8 (2010): 1155. http://dx.doi.org/10.1071/ch10098.

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The present paper highlights analogies between one of the most efficient control radical polymerization techniques namely the reversible addition–fragmentation chain transfer process, and the catalyzed polyethylene chain growth, the only technique that can controlled olefins polymerization through coordination chemistry under catalytic conditions.

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30

Reyhani, Amin, Thomas G. McKenzie, Qiang Fu e Greg G. Qiao. "Redox-Initiated Reversible Addition–Fragmentation Chain Transfer (RAFT) Polymerization". Australian Journal of Chemistry 72, n.º 7 (2019): 479. http://dx.doi.org/10.1071/ch19109.

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Reversible addition–fragmentation chain transfer (RAFT) polymerization initiated by a radical-forming redox reaction between a reducing and an oxidizing agent (i.e. ‘redox RAFT’) represents a simple, versatile, and highly useful platform for controlled polymer synthesis. Herein, the potency of a wide range of redox initiation systems including enzyme-mediated redox reactions, the Fenton reaction, peroxide-based reactions, and metal-catalyzed redox reactions, and their application in initiating RAFT polymerization, are reviewed. These redox-RAFT polymerization methods have been widely studied for synthesizing a broad range of homo- and co-polymers with tailored molecular weights, compositions, and (macro)molecular structures. It has been demonstrated that redox-RAFT polymerization holds particular promise due to its excellent performance under mild conditions, typically operating at room temperature. Redox-RAFT polymerization is therefore an important and core part of the RAFT methodology handbook and may be of particular importance going forward for the fabrication of polymeric biomaterials under biologically relevant conditions or in biological systems, in which naturally occurring redox reactions are prevalent.

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31

Truong, Nghia P., Glen R. Jones, Kate G. E. Bradford, Dominik Konkolewicz e Athina Anastasaki. "A comparison of RAFT and ATRP methods for controlled radical polymerization". Nature Reviews Chemistry 5, n.º 12 (18 de outubro de 2021): 859–69. http://dx.doi.org/10.1038/s41570-021-00328-8.

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Mori, Hideharu, Kazuhiko Sutoh e Takeshi Endo. "Controlled Radical Polymerization of an Acrylamide Containingl-Phenylalanine Moiety via RAFT". Macromolecules 38, n.º 22 (novembro de 2005): 9055–65. http://dx.doi.org/10.1021/ma0509558.

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33

Ganda, Sylvia, Yanyan Jiang, Donald S. Thomas, Jeaniffer Eliezar e Martina H. Stenzel. "Biodegradable Glycopolymeric Micelles Obtained by RAFT-controlled Radical Ring-Opening Polymerization". Macromolecules 49, n.º 11 (2 de junho de 2016): 4136–46. http://dx.doi.org/10.1021/acs.macromol.6b00266.

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34

Kaiser, Andreas, Sven Brandau, Michael Klimpel e Christopher Barner-Kowollik. "Acrylonitrile-Butadiene Rubber (NBR) Prepared via Living/Controlled Radical Polymerization (RAFT)". Macromolecular Rapid Communications 31, n.º 18 (6 de setembro de 2010): 1616–21. http://dx.doi.org/10.1002/marc.201000162.

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35

Liu, Xuejing, Qiang Sun, Yan Zhang, Yujun Feng e Xin Su. "Rapid RAFT Polymerization of Acrylamide with High Conversion". Molecules 28, n.º 6 (13 de março de 2023): 2588. http://dx.doi.org/10.3390/molecules28062588.

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Rapid RAFT polymerization can significantly improve production efficiency of PAM with designed molecular structure. This study shows that ideal Reversible Addition–Fragmentation Chain Transfer (RAFT) polymerization of acrylamide is achieved in dimethyl sulfoxide (DMSO) solution at 70 °C. The key to success is the appropriate choice of both a suitable RAFT chain transfer agent (CTA) and initiating species. It is illustrated that dodecyl trithiodimethyl propionic acid (DMPA) is a suitable trithiocarbonate RAFT CTA and is synthesized more easily than other CTAs. Compared to other RAFT processes of polymers, the reaction system shortens reaction time, enhances conversion, and bears all the characteristics of a controlled radical polymerization. The calculation result shows that high concentrations can reduce high conversions, accelerate the reaction rate, and widen molecular weight distributions slightly. This work proposes an excellent approach for rapid synthesis of PAMs with a restricted molecular weight distribution.

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36

Fu, Q., K. Xie, T. G. McKenzie e G. G. Qiao. "Trithiocarbonates as intrinsic photoredox catalysts and RAFT agents for oxygen tolerant controlled radical polymerization". Polymer Chemistry 8, n.º 9 (2017): 1519–26. http://dx.doi.org/10.1039/c6py01994c.

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In this study, we reported on the discovery that trithiocarbonates (RAFT agents) can act as intrinsic photocatalyst to significantly reduce the oxygen level in a controlled radical polymerization under visible light irridation.

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37

Zhang, Zhenghe, Pengcheng Zhang, Yong Wang e Weian Zhang. "Recent advances in organic–inorganic well-defined hybrid polymers using controlled living radical polymerization techniques". Polymer Chemistry 7, n.º 24 (2016): 3950–76. http://dx.doi.org/10.1039/c6py00675b.

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Controlled living radical polymerizations, such as ATRP and RAFT polymerization, could be utilized for the preparation of well-defined organic–inorganic hybrid polymers based on POSS, PDMS, silica nanoparticles, graphene, CNTs and fullerene.

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38

Bayburdov, Telman A., e Sergei L. Shmakov. "Branched polymers of N-isopropylacrylamide: A 2005–2020 review of english literature". Izvestiya of Saratov University. New Series. Series: Chemistry. Biology. Ecology 21, n.º 1 (2021): 12–22. http://dx.doi.org/10.18500/1816-9775-2021-21-1-12-22.

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The search and the analysis of English scientific literature from 2005 to 2020 devoted to the methods of obtaining branched polymers and copolymers of N-isopropylacrylamide were made in order to obtain novel materials with valuable properties. It was found that modern methods of controlled radical polymerization were mainly used for this purpose, namely, atom transfer radical polymerization (ATRP), polymerization with reversible addition-fragmentation chain transfer (RAFT) and group transfer polymerization (GTP). In most cases the original compounds were the chain transfer agents in RAFT. CuCl was commonly used as a catalyst in ATRP; while in some cases cores of a different chemical nature (β-cyclodextrin, zinc phthalocyanine or zinc porphyrin) were used. In a number of cases, click chemistry reactions were used for synthesis. Depending on the order of the synthesis, a distinction was made between the “corearms” and “arms-core” approaches. The prospects of using branched N-isopropylacrylamide polymers as thermoresponsive materials, membranes for controlled drug release, photocatalysts, and agents of targeted photodynamic therapy and photoelectric storage of information were estimated.

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39

Ma, Qiang, Xun Zhang, Yu Jiang, Junqiang Lin, Bernadette Graff, Siping Hu, Jacques Lalevée e Saihu Liao. "Organocatalytic PET-RAFT polymerization with a low ppm of organic photocatalyst under visible light". Polymer Chemistry 13, n.º 2 (2022): 209–19. http://dx.doi.org/10.1039/d1py01431e.

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The development of light-mediated controlled radical polymerization has benefited from the discovery of novel photocatalysts, which could allow precise light control over the polymerization process and the production of well-defined polymers.

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40

Al-Harthi, Mamdouh A. "Highlight on the Mathematical Modeling of Controlled Free Radical Polymerization". International Journal of Polymer Science 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/469353.

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Over the last quarter century, controlled free radical polymerization (CFRP) has received great attention by the researchers of polymer science and engineering. In addition to the experimental studies, many publications in the literature dealt with the modeling of CFRP processes. A review of acknowledged and well-received researches on mathematical modeling in the area of CFRP is presented in this work. Three main categories of CFRP (namely, ATRP, RAFT, and NMP) are taken into consideration in the review. The different techniques used in modeling CFRP processes are also enumerated with more emphasis on Monte Carlo simulation and the method of moments. The review provides a better understanding of the processes and the recent efforts to model CFRP.

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Britner, Judita, e Helmut Ritter. "Methylenelactide: vinyl polymerization and spatial reactivity effects". Beilstein Journal of Organic Chemistry 12 (14 de novembro de 2016): 2378–89. http://dx.doi.org/10.3762/bjoc.12.232.

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The first detailed study on free-radical polymerization, copolymerization and controlled radical polymerization of the cyclic push–pull-type monomer methylenelactide in comparison to the non-cyclic monomer α-acetoxyacrylate is described. The experimental results revealed that methylenelactide undergoes a self-initiated polymerization. The copolymerization parameters of methylenelactide and styrene as well as methyl methacrylate were determined. To predict the copolymerization behavior with other classes of monomers, Q and e values were calculated. Further, reversible addition fragmentation chain transfer (RAFT)-controlled homopolymerization of methylenelactide and copolymerization with N,N-dimethylacrylamide was performed at 70 °C in 1,4-dioxane using AIBN as initiator and 2-(((ethylthio)carbonothioyl)thio)-2-methylpropanoic acid as a transfer agent.

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42

Li, Song Tao, Dan Li e Chun Ju He. "Synthesis of Allyl Functionalized Telechelic PVP by Reversible Addition-Fragmentation Chain Transfer (RAFT) Polymerization". Materials Science Forum 789 (abril de 2014): 235–39. http://dx.doi.org/10.4028/www.scientific.net/msf.789.235.

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Telechelic polymers have been explored widely because they are precursors for preparing multi-block copolymers, grafted polymers, star polymers, and polymer networks [1-2]. A variety of telechelic polymers with terminals like hydroxy, carboxylic, epoxy groups and carbon–carbon double bond have been prepared by controlled radical polymerization (CRP) techniques including nitroxide-mediated polymerization (NMP), atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer polymerization (RAFT)[3-5].The CRP techniques can not only control the molecular weight but also can be carried out in the presence of many functional groups from monomers, initiators, or chain transfer agents (CTA).

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Way, Débora Vieira, Rayany Stôcco Braido, Sabrina Alves dos Reis, Flávio Alves Lara e José Carlos Pinto. "Miniemulsion RAFT Copolymerization of MMA with Acrylic Acid and Methacrylic Acid and Bioconjugation with BSA". Nanomaterials 9, n.º 6 (31 de maio de 2019): 828. http://dx.doi.org/10.3390/nano9060828.

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Polymerization through reversible addition-fragmentation chain-transfer (RAFT) polymerization has been extensively employed for the production of polymers with controlled molar mass, complex architectures and copolymer composition distributions intended for biomedical and pharmaceutical applications. In the present work, RAFT miniemulsion copolymerizations of methyl methacrylate with acrylic acid and methacrylic acid were conducted to prepare hydrophilic polymer nanoparticles and compare cell uptake results after bioconjugation with bovine serum albumin (BSA), used as a model biomolecule. Obtained results indicate that the RAFT agent 2-cyano-propyl-dithiobenzoate allowed for successful free radical controlled methyl methacrylate copolymerizations and performed better when methacrylic acid was used as comonomer. Results also indicate that poly(methyl methacrylate-co-methacrylic acid) nanoparticles prepared by RAFT copolymerization and bioconjugated with BSA were exceptionally well accepted by cells, when compared to the other produced polymer nanoparticles because cellular uptake levels were much higher for particles prepared in presence of methacrylic acid, which can probably be associated to its high hydrophilicity.

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44

Moraes, Rodolfo M., Layde T. Carvalho, Gizelda M. Alves, Simone F. Medeiros, Elodie Bourgeat-Lami e Amilton M. Santos. "Synthesis and Self-Assembly of Poly(N-Vinylcaprolactam)-b-Poly(ε-Caprolactone) Block Copolymers via the Combination of RAFT/MADIX and Ring-Opening Polymerizations". Polymers 12, n.º 6 (30 de maio de 2020): 1252. http://dx.doi.org/10.3390/polym12061252.

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Well-defined amphiphilic, biocompatible and partially biodegradable, thermo-responsive poly(N-vinylcaprolactam)-b-poly(ε-caprolactone) (PNVCL-b-PCL) block copolymers were synthesized by combining reversible addition-fragmentation chain transfer (RAFT) and ring-opening polymerizations (ROP). Poly(N-vinylcaprolactam) containing xanthate and hydroxyl end groups (X–PNVCL–OH) was first synthesized by RAFT/macromolecular design by the interchange of xanthates (RAFT/MADIX) polymerization of NVCL mediated by a chain transfer agent containing a hydroxyl function. The xanthate-end group was then removed from PNVCL by a radical-induced process. Finally, the hydroxyl end-capped PNVCL homopolymer was used as a macroinitiator in the ROP of ε-caprolactone (ε-CL) to obtain PNVCL-b-PCL block copolymers. These (co)polymers were characterized by Size Exclusion Chromatography (SEC), Fourier-Transform Infrared spectroscopy (FTIR), Proton Nuclear Magnetic Resonance spectroscopy (1H NMR), UV–vis and Differential Scanning Calorimetry (DSC) measurements. The critical micelle concentration (CMC) of the block copolymers in aqueous solution measured by the fluorescence probe technique decreased with increasing the length of the hydrophobic block. However, dynamic light scattering (DLS) demonstrated that the size of the micelles increased with increasing the proportion of hydrophobic segments. The morphology observed by cryo-TEM demonstrated that the micelles have a pointed-oval-shape. UV–vis and DLS analyses showed that these block copolymers have a temperature-responsive behavior with a lower critical solution temperature (LCST) that could be tuned by varying the block copolymer composition.

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Janoschka, Tobias, Anke Teichler, Andreas Krieg, Martin D. Hager e Ulrich S. Schubert. "Polymerization of free secondary amine bearing monomers by RAFT polymerization and other controlled radical techniques". Journal of Polymer Science Part A: Polymer Chemistry 50, n.º 7 (24 de janeiro de 2012): 1394–407. http://dx.doi.org/10.1002/pola.25907.

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Destarac, Mathias, Wojciech Bzducha, Daniel Taton, Isabelle Gauthier-Gillaizeau e Samir Z. Zard. "Xanthates as Chain-Transfer Agents in Controlled Radical Polymerization (MADIX): Structural Effect of the O-Alkyl Group". Macromolecular Rapid Communications 23, n.º 17 (dezembro de 2002): 1049–54. http://dx.doi.org/10.1002/marc.200290002.

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Malic, Nino, e Richard A. Evans. "Synthesis of Carboxylic Acid and Ester Mid-Functionalized Polymers using RAFT Polymerization and ATRP". Australian Journal of Chemistry 59, n.º 10 (2006): 763. http://dx.doi.org/10.1071/ch06317.

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Polymers with a single central point of carboxylic acid functionality were prepared by living radical polymerization methods, RAFT and ATRP. A convenient water-based synthesis of a Y-branched ATRP initiator from 3,5-dihydroxybenzoic acid and 2-bromopropionyl bromide, from which the Y-branched RAFT agent is then subsequently derived, is described. Polymerization occurred uniformly from both of the RAFT groups to give chains of equal length as shown by hydrolysis. ATRP polymerization based on an ester derivative of 3,5-bis(2-bromopropionyloxy)benzoic acid as initiator was well controlled, whereas the free carboxylic acid gave inconsistent performance. The ability to couple functional molecules to the middle of polymers would provide better protection or interaction of the functional molecule with the polymer than conventional end attachment. This would find applications such as in drug delivery where more efficient protection would allow the use of lower molecular weight polymers.

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Wang, Hyun Suk, e Athina Anastasaki. "Chemical Recycling of Polymethacrylates Synthesized by RAFT Polymerization". CHIMIA 77, n.º 4 (26 de abril de 2023): 217. http://dx.doi.org/10.2533/chimia.2023.217.

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Reversing controlled radical polymerization and regenerating the monomer has been a long-standing challenge for fundamental research and practical applications. Herein, we report a highly efficient depolymerization method for various polymethacrylates synthesized by reversible addition-fragmentation chain-transfer (RAFT) polymerization. The depolymerization process, which does not require any catalyst, exhibits near-quantitative conversions of up to 92%. The key aspect of our approach is the utilization of the high end-group fidelity of RAFT polymers to generate chain-end radicals at 120 °C. These radicals trigger a rapid unzipping of the polymethacrylates. The depolymerization product can be utilized to either reconstruct the linear polymer or create an entirely new insoluble gel that can also be subjected to depolymerization. Our depolymerization strategy offers a promising route towards the development of sustainable and efficient recycling methods for complex polymer materials.

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Nguyen, Duc Hung, e Philipp Vana. "On the Mechanism of Radical Polymerization of Methyl Methacrylate with Dithiobenzoic Acid as Mediator". Australian Journal of Chemistry 59, n.º 8 (2006): 549. http://dx.doi.org/10.1071/ch06158.

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Dithiobenzoic acid (DTBA) induces controlled polymerization behaviour in methyl methacrylate polymerization at 60°C, accompanied by a pronounced induction period of several hours. DTBA is partially transformed during this induction period into a dithioester with a tertiary ester group moiety, which constitutes an efficient reversible addition–fragmentation chain transfer (RAFT) agent. The transformation reaction is proposed to proceed via a hydrogen abstraction from DTBA by radicals and subsequent termination of the formed phenylcarbonothioylsulfanyl radical with propagating radicals. The proposed reaction scheme was implemented into a computer model, by which the rate coefficient of the hydrogen abstraction from DTBA and of the reinitiation of the intermediate phenylcarbonothioylsulfanyl radical was estimated. The model is in agreement with all of the species observable by electrospray ionization mass spectrometry, with the extent of the experimental induction periods, and with the absolute concentrations of dithioesters that act as efficient RAFT agents during the polymerization. A protocol that uses a cocktail of initiators is introduced, by which the induction period in DTBA-mediated polymerization is effectively eliminated.

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Pozdnyakov, Alexander S., Nadezhda P. Kuznetsova, Tatyana A. Semenova, Yuliya I. Bolgova, Anastasia A. Ivanova, Olga M. Trofimova e Artem I. Emel’yanov. "Dithiocarbamates as Effective Reversible Addition–Fragmentation Chain Transfer Agents for Controlled Radical Polymerization of 1-Vinyl-1,2,4-triazole". Polymers 14, n.º 10 (16 de maio de 2022): 2029. http://dx.doi.org/10.3390/polym14102029.

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Narrow dispersed poly(1-vinyl-1,2,4-triazole) (PVT) was synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization of 1-vinyl-1,2,4-triazole (VT). AIBN as the initiator and dithiocarbamates, xanthates, and trithiocarbonates as the chain transfer agents (CTA) were used. Dithiocarbamates proved to be the most efficient in VT polymerization. Gel permeation chromatography was used to determine the molecular weight distribution and polydispersity of the synthesized polymers. The presence of the CTA stabilizing and leaving groups in the PVT was confirmed by 1H and 13C NMR spectroscopy. The linear dependence of the degree of polymerization on time confirms the conduct of radical polymerization in a controlled mode. The VT conversion was over 98% and the PVT number average molecular weight ranged from 11 to 61 kDa. The polydispersity of the synthesized polymers reached 1.16. The occurrence of the controlled radical polymerization was confirmed by monitoring the degree of polymerization over time.

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