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David M Haddleton - One of the best experts on this subject based on the ideXlab platform.
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cu 0 rdrp of Methacrylates in dmso importance of the initiator
Polymer Chemistry, 2018Co-Authors: Glen R Jones, Richard Whitfield, Athina Anastasaki, Nuttapol Risangud, Alexandre Simula, Daniel J Keddie, David M HaddletonAbstract:The controlled radical polymerization of Methacrylates via Cu(0)-mediated RDRP is challenging in comparison to acrylates with most reports illustrating higher dispersities, lower monomer conversions and poorer end group fidelity relative to the acrylic analogues. Herein, we present the successful synthesis of poly(methyl Methacrylate) (PMMA) in DMSO by judicious selection of optimal reaction conditions. The effect of the initiator, ligand and temperature on the rate and control of the polymerization is investigated and discussed. Under carefully optimized conditions enhanced control over the molecular weight distributions is obtained furnishing methacrylic polymers with dispersities as low as 1.10, even at very high conversions. A range of Methacrylates were found to be tolerant to the optimized polymerization conditions including hydrophobic, hydrophilic and functional Methacrylates including methyl and benzyl Methacrylate, ethylene glycol methyl ether Methacrylate and glycidyl Methacrylate. The control retained during the polymerization is further highlighted by in situ chain extensions yielding well-defined block polyMethacrylates.
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set lrp of Methacrylates in fluorinated alcohols
Polymer Chemistry, 2013Co-Authors: Shampa R Samanta, Athina Anastasaki, David M Haddleton, Christopher Waldron, Virgil PercecAbstract:Activated Cu(0) wire-mediated single-electron transfer living radical polymerization (SET-LRP) of methyl Methacrylate (MMA), ethyl Methacrylate (EMA) and n-butyl Methacrylate (BMA) was performed in two fluorinated alcohols, 2,2,2-trifluoroethanol (TFE) and 2,2,3,3-tetrafluoropropanol (TFP) using tosyl chloride (TsCl) as initiator, hydrazine-activated Cu(0) wire as catalyst, and Me6-TREN as ligand at 50 °C. The ability of these two solvents to solubilize these monomers, the resulting polymers, and mediate an efficient disproportionation of Cu(I)Br in the presence of Me6-TREN ligand to produce the “nascent” Cu(0) activator, Cu(II)Br2 deactivator and to stabilize Cu(II)Br2/Me6-TREN complex make them excellent solvents for SET-LRP of Methacrylates. To the best of our knowledge, this is the first report of SET-LRP of Methacrylates in fluorinated alcohols and also the first efficient SET-LRP of EMA and BMA in any solvent. The kinetic experiments and molecular weight analyses demonstrate that in all experiments a living polymerization takes place with excellent evolution of molecular weight and with narrow molecular weight distribution until almost complete monomer conversion. It was also demonstrated that the rate of polymerization conducted in TFE and TFP could be significantly enhanced by a synergistic solvent effect upon addition of a small amount of water, which mediates an even faster disproportionation of Cu(I)Br into Cu(0) activator and Cu(II)Br2 deactivator.
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copper mediated living radical polymerisation interactions between monomer and catalyst
Dalton Transactions, 2003Co-Authors: Jeetan Lad, Simon Harrisson, Giuseppe Mantovani, David M HaddletonAbstract:The mechanism of copper(I) mediated living radical polymerisation (ATRP) of vinyl monomers has been widely assumed to be relatively simple. However, monomer reactivity ratios in ATRP can be significantly different from those in conventional radical polymerisation, and the exact nature of the catalyst is not well understood due to rapid exchange of ligand and monomer at the copper centre under the polymerisation conditions. This paper illustrates aspects of this catalyst system, which complicate the accepted mechanism of this new and important reaction. Coordination of aminoethyl Methacrylates and methoxy[poly(ethylene glycol)] Methacrylate monomers is demonstrated by NMR with rMMA = 0.96(2), 0.98(1) and 0.97(1) for dimethylaminoethyl Methacrylate (DMAEMA), (diethylamino)ethyl Methacrylate (DEAEMA) and (tert-butylamino)ethyl Methacrylate (TBAEMA) under free radical polymerisation and 0.74(3), 0.79(3) and 0.69(3) for transition-metal mediated polymerisation.
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Living Radical Polymerization Immobilized on Wang Resins: Synthesis and Harvest of Narrow Polydispersity Poly(Methacrylate)s
Macromolecules, 2001Co-Authors: Stéphanie Angot, Neil Ayres, David M HaddletonAbstract:Wang resin has been transformed into an initiator for copper(I)-mediated living radical polymerization of Methacrylates at initiator loading of 0.9 and 3.5 mmol g-1. The immobilized initiator was characterized by ATR FTIR, gel phase 13C NMR, and solid-state CP/MAS 13C NMR using two different spinning frequencies as well as a TOSS pulse sequence. The immobilized initiator has been used to prepare poly(methyl Methacrylate), PMMA, homopolymer, and poly(methyl Methacrylate)-block-poly(benzyl Methacrylate-co-methyl Methacrylate), P(MMA)-block-P(BzMA-co-MMA), block copolymers. The poly(Methacrylate)s have been harvested from the insoluble resin by a simple trifluoroacetic acid, TFA, wash which selectively cleaved the activated benzyl ester linkage, so as to facilitate analysis. At an initiator loading of 0.9 mmol g-1 the Mn increases linearly with conversion with kinetics following first-order behavior in monomer as would be expected for living polymerization. After 3 h a 61.9% conversion of MMA is reached, wit...
Toyoji Kakuchi - One of the best experts on this subject based on the ideXlab platform.
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b c6f5 3 catalyzed group transfer polymerization of alkyl Methacrylates with dimethylphenylsilane through in situ formation of silyl ketene acetal by b c6f5 3 catalyzed 1 4 hydrosilylation of Methacrylate monomer
Polymer Chemistry, 2015Co-Authors: Yougen Chen, Kodai Kitano, Shinji Tsuchida, Seiya Kikuchi, Kenji Takada, Toshifumi Satoh, Toyoji KakuchiAbstract:The group transfer polymerization (GTP) of alkyl Methacrylates has been studied using hydrosilane and tris(pentafluorophenyl)borane (B(C6F5)3) as the new initiation system. For the B(C6F5)3-catalyzed polymerization of methyl Methacrylate (MMA) using triethylsilane, tri-n-butylsilane (nBu3SiH), dimethylphenylsilane (Me2PhSiH), triphenylsilane, and triisopropylsilane, nBu3SiH and Me2PhSiH were suitable for producing well-defined polymers with predicted molar masses and a low polydispersity. The livingness of the GTP of MMA using Me2PhSiH/B(C6F5)3 was verified by the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) measurement of the resulting polymers, kinetic analyses, and chain extension experiments. The B(C6F5)3-catalyzed GTP using Me2PhSiH was also applicable for other alkyl Methacrylates, such as the n-propyl, n-hexyl, n-decyl, 2-ethylhexyl, iso-butyl, and cyclohexyl Methacrylates. The in situ formation of the silyl ketene acetal by the 1,4-hydrosilylation of MMA was proved by the MALDI-TOF MS and 2H NMR measurements of the polymers obtained from the B(C6F5)3-catalyzed GTPs of MMA with Me2PhSiH or Me2PhSiD, which was terminated using CH3OH or CD3OD.
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synthesis and radical polymerization of end Methacrylated poly succinimide leading to poly aspartic acid hydrogel
Macromolecular Rapid Communications, 1999Co-Authors: Toyoji Kakuchi, Atsushi Kusuno, Minako Shibata, Takeshi NakatoAbstract:The polycondensation of aspartic acid in the presence of phthalic anhydride was carried out in mesitylene/sulfolane using o-phosphoric acid as a catalyst. The polymer yields were 91–78%, when 5–20 mol-% phthalic anhydride was added into the feed. The obtained poly(succinimide) carried a phthalic imide unit and a succinic acid unit as end groups. In the MALDI-TOF mass spectrum, the peak-to-peak distances between adjacent signals were 97.07 m/z, corresponding to the calculated value (97.07) of the succinimide unit. Poly(succinimide) was reacted with 2-(methacryloxy)ethyl isocyanate to give end-Methacrylated poly-(succinimide), in which the end-functionality of the Methacrylate group was ca. 1. End-Methacrylated poly-(succinimide) was polymerized with ethylene glycol diMethacrylate using 2,2′-azoisobutyronitrile to give poly(succinimide) gel, which could be converted into water-absorbing poly(aspartic acid) hydrogel.
Krzysztof Matyjaszewski - One of the best experts on this subject based on the ideXlab platform.
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synergic effect between nucleophilic monomers and cu ii metal organic framework for visible light triggered controlled photopolymerization
Chemistry of Materials, 2017Co-Authors: Huichun Lee, Krzysztof Matyjaszewski, Marco Fantin, Markus Antonietti, Bernhard V K J SchmidtAbstract:A Cu(II) metal-organic framework (MOF), Cu2(bdc)2(dabco), was found to be an efficient heterogeneous catalyst for controlled photopolymerization under visible light. The MOF, composed of photostimulable metal sites, was used to catalyze both photoninitiation as well as radical chain control and requires no external photoinitiator, dye sensitizer or ligand. A simple light trigger allowed the photoreduction of Cu(II) to the active Cu(I) state, enabling controlled atom transfer radical polymerization (ATRP). Compared to conventional ATRP with homogeneous catalysts, the ionic-bonded framework imparts high stability and robustness to the catalytic Cu(II) species. Therefore, the polymerization of vinylpyridines (2-vinylpyridine, 2VP and 4-vinylpyridine, 4VP), usually challenging by traditional polymerization strategies, was controlled up to high conversion (> 85 %) in 90 min, forming polymers with Ɖ < 1.3. Methacrylates such as 2-(dimethylamino)ethyl Methacrylate (DMAEMA) and methyl Methacrylate were polymerize...
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photoinduced fe based atom transfer radical polymerization in the absence of additional ligands reducing agents and radical initiators
Macromolecules, 2015Co-Authors: Xiangcheng Pan, Nikhil Malhotra, Jianan Zhang, Krzysztof MatyjaszewskiAbstract:A photoinduced atom transfer radical polymerization (ATRP) of Methacrylate with a Fe-based catalytic system was studied in the absence of additional ligands, reducing agents, and radical initiators. Linear semilogarithmic polymerization kinetics and narrow molecular weight distributions were obtained in the presence but also absence of conventional ATRP initiators. The proposed mechanism involves monomer-mediated photoreduction of Fe(III) to Fe(II) but also photoactivation of Fe(II) species. The polymerization was studied with different radiation sources for several Methacrylates. The technique was successfully used to synthesize block copolymers, confirming the living nature of ATRP.
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successful chain extension of polyacrylate and polystyrene macroinitiators with Methacrylates in an arget and icar atrp
Macromolecules, 2007Co-Authors: Laura Mueller, Wojciech Jakubowski, Wei Tang, Krzysztof MatyjaszewskiAbstract:Well-defined block copolymers poly(n-butyl acrylate)-b-poly(methyl Methacrylate-co-styrene) and polystyrene-b-poly(methyl Methacrylate-co-styrene) were synthesized using activators regenerated by electron transfer (ARGET) and initiators for continuous activator regeneration (ICAR) for atom transfer radical polymerization (ATRP). In order to overcome the poor initiation efficiency of polystyrene and poly(n-butyl acrylate) macroinitiators during chain extension with Methacrylates, a small amount of styrene was used as a comonomer in the second block. To determine the percentage of styrene necessary for efficient chain extension, studies with low molecular weight alkyl halide initiators that model the poly(n-butyl acrylate) and polystyrene macroinitiators, respectively, were performed. Extension from the macroinitiators was then conducted using the appropriate methyl Methacrylate/styrene comonomer mixture to obtain well-defined block copolymers, for example, starting from poly(n-butyl acrylate) macroinitiato...
Jun-ichi Yoshida - One of the best experts on this subject based on the ideXlab platform.
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anionic polymerization of alkyl Methacrylates using flow microreactor systems
Chemical Engineering Journal, 2011Co-Authors: Aiichiro Nagaki, Atsuo Miyazaki, Yutaka Tomida, Jun-ichi YoshidaAbstract:Abstract Living anionic polymerization of alkyl Methacrylates initiated by 1,1-diphenylhexyllithium was conducted in a flow microreactor system. A high level of molecular-weight distribution control was achieved under easily accessible conditions, such as at −28 °C (MMA: Mw/Mn = 1.16), 0 °C (BuMA: Mw/Mn = 1.24) and 24 °C (Bu t MA: Mw/Mn = 1.12). The molecular weight (Mn) increased with an increase in the monomer/initiator ratio. The subsequent reaction of a reactive polymer chain end with a second alkyl Methacrylate in integrated flow micoreactor systems led to the formation of a block copolymer having narrow molecular-weight distribution.
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synthesis of polystyrenes poly alkyl Methacrylates block copolymers via anionic polymerization using an integrated flow microreactor system
Macromolecules, 2010Co-Authors: Aiichiro Nagaki, Atsuo Miyazaki, Jun-ichi YoshidaAbstract:The polystyrene living polymer end, which was produced by butyllithium initiated anionic polymerization of styrene in a flow microreactor system was found to be effectively trapped with 1,1-diphenylethylene. The resulting organolithium species could be used as a macro initiator for anionic polymerization of alkyl Methacrylates to obtain styrene−alkyl Methacrylate diblock copolymers using an integrated flow microreactor system. A high level of control of molecular weight was achieved at easily accessible temperatures such as +24 to −28 °C by virtue of the fast mixing, fast heat transfer, and residence time control. Triblock copolymers were also synthesized by sequential introduction of styrene and two different alkyl Methacrylates in a similar manner.
Sabine Beuermann - One of the best experts on this subject based on the ideXlab platform.
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influence of monomer structure on the propagation kinetics of acrylate and Methacrylate homopolymerizations studied via plp sec in fluid co2
Macromolecular Chemistry and Physics, 2004Co-Authors: Sabine Beuermann, Michael Buback, Veronique El Rezzi, Michael Jurgens, Dorit NelkeAbstract:Propagation kinetics of free-radical homopolymerizations of methyl acrylate, dodecyl acrylate, butyl Methacrylate, dodecyl Methacrylate, glycidyl Methacrylate, cyclohexyl Methacrylate, and isobornyl Methacrylate, in solutions containing 40 wt.-CO 2 were applying the PLP-SEC technique. The obtained apparent propagation rate coefficient, k p,app , are by up to 40% below the associated bulk k p values. This reductioon is assigned to a lowering of local monomer concentration, c M,loc , at the site of the free-radical chain end rather than to a decrease of the actual propagation rate coefficient . With the alkyl(meth)acrylates, intersegmental interactions between polar groups of the same polymer molecule are disponible for deviations of c M,loc , from the analytical overall monomer concentration, c M,a . Increasing size of the flexible alky ester group reduces the differences between c M,loc , and c M,a due to shielding effects. Methacrylates with cyclic ester groups do not follow this trend. In case of isobornyl Methacrylate, which polymerizes to a rigid material with large side groups, relative size of monomer and CO 2 matters and reduces c M,loc significantly below c M,a .
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determination of free radical propagation rate coefficients for cycloalkyl and functional Methacrylates by pulsed laser polymerization
Macromolecules, 1998Co-Authors: Robin A Hutchinson, Sabine Beuermann, Donald Albert Paquet, J H Mcminn, Christian JacksonAbstract:Free-radical propagation rate coefficients (kp) for three cycloalkyl Methacrylates and two functional Methacrylates were measured at temperatures between 30 and 110 °C. The data were obtained by analyzing molecular weight distributions of polymer produced by pulsed-laser polymerization − the PLP/MWD technique. Arrhenius parameters were compared with recent results reported for linear and branched alkyl Methacrylates, including methyl Methacrylate (MMA) and n-dodecyl Methacrylate (DMA). The highest kp value, for 2-hydroxypropyl Methacrylate, is more than twice the MMA value, and is 50% higher than the DMA value at 50 °C. The monomer with the lowest kp value, isobornyl Methacrylate, has a coefficient of similar magnitude to DMA. Values for the other three monomers − glycidyl, cyclohexyl, and benzyl Methacrylates − are intermediate between these two levels.
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determination of free radical propagation rate coefficients for alkyl Methacrylates by pulsed laser polymerization
Macromolecules, 1997Co-Authors: Robin A Hutchinson, Sabine Beuermann, Donald Albert Paquet, J H McminnAbstract:Values of free-radical propagation rate coefficients (kp) for two new Methacrylate monomers2-ethylhexyl and isodecyl Methacrylateshave been measured in the temperature range 10−90 °C by analyzing molecular weight distributions of polymer produced by pulsed-laser polymerization (the PLP/MWD technique). In addition, new PLP/MWD results for n-butyl and n-dodecyl Methacrylates are reported, and previously published data for ethyl and isobutyl Methacrylates are reanalyzed. The temperature dependence of kp for these six monomers is compared to that recently reported for methyl Methacrylate. A consistent increase of kp with size of the ester group is observed, with values for n-dodecyl Methacrylate 50−60% higher than those for methyl Methacrylate. Although this increase is statistically significant, it is less certain whether it is attributable to a decrease in the activation energy or an increase in the frequency factor. The experimental results favor the former explanation.
