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Journal ArticleDOI

Synthesis and Characterization of Block Copolymers of P(MMA‐b‐n‐BA‐b‐MMA) via Ambient Temperature ATRP of MMA

13 Apr 2005-Journal of Macromolecular Science, Part A (Taylor & Francis Group)-Vol. 42, Iss: 4, pp 471-484
TL;DR: A binol ester initiator was used as a bifunctional ATRP initiator in combination with PMDETA/copper bromide catalyst system in DMF to synthesize n-butyl acrylate macroinitiator at 50°C.
Abstract: A binol ester initiator was used as a bifunctional ATRP initiator in combination with PMDETA/copper bromide catalyst system in DMF to synthesize n‐butyl acrylate macroinitiator at 50°C. The resulting macroinitiator was used for a detailed investigation of the ATRP of methyl methacrylate (MMA) with CuCl/N,N,N′,N′,N″‐pentamethyldiethy‐lenetriamine (PMDETA) catalyst system in anisole at 30°C. Thus, the MMA polymerization is shown to proceed with first order kinetics, with predicted molecular weight and narrow polydispersity indices. Gel permeation chromatography (GPC) and NMR were used for the characterization of the polymers synthesized.
Citations
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Patent
22 Feb 2011
TL;DR: In this article, the ORI/Ti molar ratio in the range 0.1-1.5 was used for the polymerization of MWD crystalline ethylene polymers.
Abstract: Catalyst components for the(co)polymerization of ethylene comprising Ti, Mg, halogen, ORI groups, where RI is a C1-C12 hydrocarbon group optionally containing heteroatoms, having ORI/Ti molar ratio in the range 0.1-1.5, a Mg/Ti molar ratio of less than 8, an amount of titanium, with respect to the total weight of said solid catalyst component, higher than 4% by weight characterized by a specific SS-NMR pattern are particularly useful for preparing narrow MWD crystalline ethylene polymers.

201 citations

Journal ArticleDOI
TL;DR: Small-angle X-ray scattering (SAXS) analysis of AB and ABA block copolymers showed scattering behavior inside the measuring limits indicating nanophase separation, however, SAXS pattern of AB diblockCopolymers indicated general phase separation only, whereas for ABA triblock copolymer an ordered or mixed morphology could be deduced, which is assumed to be the reason for the better mechanical properties achieved with ABABlocks.
Abstract: Acrylic block copolymers have several advantages over conventional styrenic block copolymers, because of the presence of a saturated backbone and polar pendant groups. This investigation reports the preparation and characterization of di- and triblock copolymers (AB and ABA types) of 2-ethylhexyl acrylate (EHA) and methyl methacrylate (MMA) via atom transfer radical polymerization (ATRP). A series of block copolymers, PEHA-block-PMMA(AB diblock) and PMMA-block-PEHA-block-PMMA(ABA triblock) were prepared via ATRP at 90 °C using CuBr as catalyst in combination with N,N,N′,N″,N″-pentamethyl diethylenetriamine (PMDETA) as ligand and acetone as additive. The chemical structure of the macroinitiators and molar composition of block copolymers were characterized by 1H NMR analysis, and molecular weights of the polymers were analyzed by GPC analysis. DSC analysis showed two glass transition temperatures (Tg), indicating formation of two domains, which was corroborated by AFM analysis. Small-angle X-ray scattering ...

37 citations

Journal ArticleDOI
TL;DR: In this paper, the graft copolymerization followed by block polymerization enabled the synthesis of highly branched polymer brush, in which the grafting density can be adjusted by appropriate choice of bromide concentration in polystyrene.
Abstract: Well defined graft copolymers are prepared by "grafting from" atom transfer radical polymerization (ATRP) at room temperature (30 °C). The experiments were aimed at grafting methacrylates and styrene at latent initiating sites of polystyrene. For this purpose, the benzylic hydrogen in polystyrene was subjected to allylic bromination with N-bromosuccinimide and azobisisobutrylnitirle to generate tertiary bromide ATRP initiating sites (Br-C-PS). The use of Br-C-PS with lesser mol % of bromide initiating groups results in better control and successful graft copolymerization. This was used to synthesize a series of new graft copolymers such as PS-g-PBnMA, PS-g-PBMA, PS-g-GMA, and PS-g-(PMMA-b-PtBA) catalyzed by CuBr/ PMDETA system, in bulk, at room temperature. The polymers are characterized by GPC, NMR, FTIR, TEM, and TGA. Graft copolymerization followed by block polymerization enabled the synthesis of highly branched polymer brush, in which the grafting density can be adjusted by appropriate choice of bromide concentration in the polystyrene.

31 citations

Journal ArticleDOI
TL;DR: In this paper, a tetrahydrofurfuryl methacrylate (THFMA) was polymerized by ambient temperature Atom Transfer Radical Polymerization (AT ATRP) using CuX/PMDETA/EBiB system.

23 citations

Journal ArticleDOI
TL;DR: In this article, a series of copper-based reverse atom transfer radical polymerizations (ATRP) were carried out for methyl methacrylate (MMA) at same conditions (in xylene, at 80°C) using N,N,N′, N′-teramethylethylendiamine (TMEDA), N, N, n′,N-N′-N-pentamethyldiethylentriamine (PMDETA), 2-2′-bipyridine, and 4,4′-Di(
Abstract: A series of copper-based reverse atom transfer radical polymerizations (ATRP) were carried out for methyl methacrylate (MMA) at same conditions (in xylene, at 80°C) using N,N,N′,N′-teramethylethylendiamine (TMEDA), N,N,N′,N′,N′-pentamethyldiethylentriamine (PMDETA), 2-2′-bipyridine, and 4,4′-Di(5-nonyl)-2,2′-bipyridine as ligand, respectively. 2,2′-azobis(isobutyronitrile) (AIBN) was used as initiator. In CuBr2/bpy system, the polymerization is uncontrolled, because of the poor solubility of CuBr2/bpy complex in organic phase. But in other three systems, the polymerizations represent controlled. Especially in CuBr2/dNbpy system, the number-average molecular weight increases linearly with monomer conversion from 4280 up to 14,700. During the whole polymerization, the polydispersities are quite low (in the range 1.07–1.10). The different results obtained from the four systems are due to the differences of ligands. From the point of molecular structure of ligands, it is very important to analyze deeply the two relations between (1) ligand and complex and (2) complex and polymerization. The different results obtained were discussed based on the steric effect and valence bond theory. The results can help us deep to understand the mechanism of ATRP. The presence of the bromine atoms as end groups of the poly(methyl methacrylate) (PMMA) obtained was determined by 1H-NMR spectroscopy. PMMA obtained could be used as macroinitiator to process chain-extension reaction or block copolymerization reaction via a conventional ATRP process. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

12 citations

References
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Journal ArticleDOI
TL;DR: In this article, the authors investigated halide exchange during atom transfer radical polymerization (ATRP) using mixed halide initiation systems, R−X/Cu−Y (X, Y = Cl or Br).
Abstract: Halide exchange during atom transfer radical polymerization (ATRP) using mixed halide initiation systems, R−X/Cu−Y (X, Y = Cl or Br), was investigated. Model studies of mixed halide initiation systems (i.e., R−X/Cu−Y, X ≠ Y) demonstrated that exchange occurs rapidly at 90 °C, and there is a clear preference for alkyl chlorides to be formed in over alkyl bromides. This was attributed mainly to the carbon−chlorine bond being stronger than the corresponding carbon−bromine bond. This implies that, in ATRP with a mixed halide initiator/catalyst system, the bulk of the polymer chain ends are terminated by chlorine if [CuCl]0 ≥ [RBr]0. Examples of using this information to improve the control in ATRP of methyl methacrylate (MMA) are presented. It was shown that, when benzyl halides were used as the initiator in the ATRP of MMA, the rate of initiation was increased relative to the rate of propagation, thus providing better control by using the benzyl bromide/copper chloride mixed halide system. Better molecular w...

341 citations


"Synthesis and Characterization of B..." refers methods in this paper

  • ...18 19 carried out the synthesis and characterization of poly(MMA‐ b ‐ n ‐BA‐ b ‐MMA) by a two‐step ATRP using the catalyst NiBr 2 (PPh 3 ) 2 ....

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Journal ArticleDOI
TL;DR: In this article, the authors used a multidentate amine ligand, tris[2-(dimethylamino)ethyl]amine (Me6TREN, Figure 1).
Abstract: Significant progress has been made in controlled/ “living” radical polymerization in recent years.1 Several new methodologies have been developed to provide control over both molecular weight and molecular weight distribution. One of the approaches is the transition metal catalyzed atom transfer radical polymerization (ATRP).2-8 Of all the transition metals investigated, copper appears to be the most promising in terms of price and versatility. A variety of monomers, including styrene9 and its derivatives,10 (methyl)acrylic esters,11,12 and acrylonitrile,13 can be polymerized in a well-controlled fashion with degree of polymerization (DP) predetermined by the ratio of the change in monomer concentration and initial initiator concentration (DP ) ∆[monomer]/[initiator]o) with polydispersities (Mw/Mn) as low as 1.05. Recently we have reported the use of multidentate amines as the ligands for copper mediated ATRP.14 Multidentate amines are less expensive, the copper complexes with these ligands generate less color to the system, and rates of polymerization are faster compared to complexes with 2,2′-bipyridine and its derivatives. In this paper, we report an improved ATRP system for the polymerization of acrylates using a new multidentate amine ligand, tris[2-(dimethylamino)ethyl]amine (Me6TREN, Figure 1). The new system allows for the wellcontrolled polymerization of acrylates at ambient temperature with very fast polymerization rates. Me6TREN can be easily prepared in a one-step synthesis using the literature procedure from commercially available tris(2-aminoethyl)amine (TREN).15 When methyl acrylate (MA) was polymerized using ethyl 2-bromopropionate (2-EBP) as the initiator and CuBr/Me6TREN as the catalyst (1.0 equiv to initiator) in a sealed tube at room temperature, the polymerization reached 85% conversion within 15 min to yield poly(methyl acrylate) (PMA) of Mn,SEC ) 21 600 (Mn,Cal ) 17 000) and Mw/Mn ) 1.18. The polymerization was exothermic, causing the solution inside the tube to boil. Better heat transfer was achieved when the polymerization was carried out in a water bath. The representative results for the ATRP of acrylates using CuBr/ Me6TREN as the catalyst are summarized in Table 1. The data in Table 1 indicates that controlled polymerizations were achieved with different catalyst-to-initiator ratios and that all the polymerizations showed high initiator efficiencies (initiator efficiency f ) Mn,Cal/ Mn,SEC) and low polydispersities. Significantly, a catalystto-initiator ratio of 0.1 was enough to prepare PMA with a polydispersity as low as 1.09. With a decrease of the catalyst-to-initiator ratio, the rate of polymerization decreased and the initiator efficiency slightly increased. The relatively lower initiator efficiency at higher catalystto-initiator ratio was likely due to the higher radical concentration at the beginning of the polymerization which resulted in the termination of some of the propagating chains by radical coupling reactions. Other acrylates, such as butyl acrylate (Table 1, entry 5), were also polymerized under similar conditions to yield welldefined polymers with low polydispersities. The employment of unmethylated TREN as the ligand resulted in the uncontrolled polymerization of MA with a much higher than predicted molecular weight and high polydispersity (Table 1, entry 6). When polymerization of MA was carried out using 2-EBP as the initiator and 0.2 equiv of CuBr/Me6TREN to initiator at 22 °C, the reaction solution quickly became viscous, and the conversion of MA reached 80% within 2 h. The reaction mixture was light green and homogeneous at the beginning, but turned heterogeneous at higher conversions. The heterogeneity was likely due to the low solubility of copper(II), generated by irreversible chain termination reactions, in the polymerization solution. A linear plot of ln([M]o/[M]) vs time was observed throughout the polymerization, indicating a constant number of growing chains (Figure 2). The molecular weight of the resulting PMA increased linearly with conversion, and the measured molecular weights were close to the calculated values Figure 1. Structure of Me6TREN.

330 citations

Journal ArticleDOI
TL;DR: In this article, the synthesis of di-and triblock copolymers, involving methyl methacrylate (MMA), butyl acrylate, and methyl acrylated, using copper-based atom transfer radical polymerization (ATRP) is reported.
Abstract: The synthesis of di- and triblock copolymers, involving methyl methacrylate (MMA), butyl acrylate, and methyl acrylate, using copper-based atom transfer radical polymerization (ATRP) is reported. It was found that poly(MMA) macroinitiator is able to initiate the ATRP of acrylic monomers. However, for polyacrylates to effectively initiate the ATRP of MMA, the end group should be a bromine atom and the catalyst CuCl; that is, halogen exchange should take place. ABA-type triblock copolymers, where B = poly(butyl acrylate) and A = poly(methyl methacrylate), were synthesized by growing the center block first using a difunctional initiator and then adding MMA to the ends.

322 citations