Synthesis of poly(methyl methacrylate) in a pyridine solution by atom transfer radical polymerization

Pyridine was used as a solvent for the atom transfer radical polymerization (ATRP) of methyl methacrylate. The homopolymerizations were carried out with methyl 2‐halopropionate (MeXPr, where X was Cl or Br) as an initiator, copper halide (CuX) as a catalyst, and 2,2′‐bipyridine as a ligand from 80 to 120 °C. The mixed halogen system methyl 2‐bromopropionate/copper chloride was also used. For all the initiator systems used, the polymerization reaction showed linear first‐order rate plots, a linear increase in the number‐average molecular weight with conversion, and relatively low polydispersities. In addition, the dependence of the polymerization rate on the temperature is presented. These data are compared with those obtained in bulk, demonstrating the effectiveness of this solvent for this monomer in ATRP. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3443–3450, 2001     

Emulsion atom transfer radical block copolymerization of 2‐ethylhexyl methacrylate and methyl methacrylate

The emulsion atom transfer radical block copolymerization of 2‐ethylhexyl methacrylate (EHMA) and methyl methacrylate (MMA) was carried out with the bifunctional initiator 1,4‐butylene glycol di(2‐bromoisobutyrate). The system was mediated by copper bromide/4,4′‐dinonyl‐2,2′‐bipyridyl and stabilized by polyoxyethylene sorbitan monooleate. The effects of the initiator concentration and temperature profile on the polymerization kinetics and latex stability were systematically examined. Both EHMA homopolymerization and successive copolymerization with MMA proceeded in a living manner and gave good control over the polymer molecular weights. The polymer molecular weights increased linearly with the monomer conversion with polydispersities lower than 1.2. A low‐temperature prepolymerization step was found to be helpful in stabilizing the latex systems, whereas further polymerization at an elevated temperature ensured high conversion rates. The EHMA polymers were effective as macroinitiators for initiating the block polymerization of MMA. Triblock poly(methyl methacrylate–2‐ethylhexyl methacrylate–methyl methacrylate) samples with various block lengths were synthesized. The MMA and EHMA reactivity ratios determined by a nonlinear least‐square method were ～0.903 and ～0.930, respectively, at 70 °C. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1914–1925, 2006     

One‐step synthesis of hyperbranched polyethylene macroinitiator and its block copolymers with methyl methacrylate or styrene via ATRP

Block copolymers of hyperbranched polyethylene (PE) and linear polystyrene (PS) or poly(methyl methacrylate) (PMMA) were synthesized via atom transfer radical polymerization (ATRP) with hyperbranched PE macroinitiators. The PE macroinitiators were synthesized through a “living” polymerization of ethylene catalyzed with a Pd‐diimine catalyst and end‐capped with 4‐chloromethyl styrene as a chain quenching agent in one step. The macroinitiator and block copolymer samples were characterized by gel permeation chromatography, ¹H and ¹³C NMR, and differential scanning calorimetry. The hyperbranched PE chains had narrow molecular weight distribution and contained a single terminal benzyl chloride per chain. Both hyperbranched PE and linear PS or PMMA blocks had well‐controlled molecular weights. Slow initiation was observed in ATRP because of steric effect of hyperbranched structures, resulting in slightly broad polydispersity index in the block copolymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3024–3032, 2010     

Synthesis of Comblike Poly（methyl methacrylate） by Atom Transfer Radical Polymerization with Poly（ethyl 2-bromoacrylate） as Macroinitiator

Comblike poly(methyl methacrylate) was synthesized by atom transfer radical polymerization of methyl methacrylate with poly(ethyl 2-bromoacrylate) as a macroinitiator, which was prepared by conventional free radical polymerization of ethyl 2-bromoacrylate. The obtained comblike polymers were characterized by GPC and ^1H NMR.     

A Simple Way for Synthesis of Alkyne-Telechelic Poly(methyl methacrylate) via Single Electron Transfer Radical Coupling Reaction

The telechelic α,ω‐alkyne‐poly(methyl methacrylate) (alkyne‐PMMA‐alkyne) was synthesized by single electron transfer radical coupling (SETRC) reaction of α‐alkyne, ω‐bromine‐poly(methyl methacrylate) (alkyne‐ PMMA‐Br). The propargyl 2‐bomoisobutyrate (PgBiB) was first prepared to initiate atom transfer radical polymerization (ATRP) of methyl methacrylate at 45°C using CuCl/1,1,4,7,10,10‐hexamethyl triethylenetetramine (HMTETA) as homogeneous catalytic system. Then the SETRC reaction was conducted at room temperature in the presence of nascent Cu(0) and N,N,N′,N′ ′,N′ ′‐pentamethyldiethyllenetriamine (PMDETA). The precursor alkyne‐PMMA‐Br and coupled product alkyne‐PMMA‐alkyne were characterized by GPC and ¹H NMR in detail.     

Synthesis of bis-allyloxy functionalized polystyrene and poly (methyl methacrylate) macromonomers using a new ATRP initiator

A new bis-allyloxy functionalized ATRP initiator, viz, 4,4-bis (4-(allyloxy) phenyl) pentyl-2-bromo-2-methylpropanoate was synthesized starting from commercially available 4,4-bis (4-hydroxyphenyl) pentanoic acid. Atom transfer radical polymerization of styrene in bulk and that of methyl methacrylate in anisole using CuBr/N,N,N′,N′,N″-pentamethyldiethylenetriamine system was carried out. The kinetic study of styrene polymerization showed controlled polymerization behavior. Bis-allyloxy functionalized well-defined polystyrene (M_n^GPC: 13,600–28,250, PDI: 1.07–1.09) and poly (methyl methacrylate) (M_n^GPC: 10,100–18,450, PDI: 1.23–1.34) macromonomers were obtained. The presence of allyloxy functionality was confirmed by ¹H NMR spectroscopy. The reactivity of allyloxy functionality was demonstrated by carrying out organic reactions such as addition of bromine and hydrosilylation on polystyrene macromonomer. Polystyrene macromonomer with bis-allyloxy functionality was transformed into bis-epoxy functionalized polystyrene macromonomer using 3-chloroperoxybenzoic acid.     

Anionic polymerization of Lewis acid-activated methyl methacrylate by enamines

A novel ionic polymerization of methyl methacrylate (MMA) with a series of enamines (1) in the presence of methylaluminum bis(2,6-di-tert-butylphenoxide) (2) was examined. Both nucleophile (1) and electrophile (2) are indispensable for the present polymerization, in which (1) acts as initiator and (2) as activator. MMA polymerization proceeded smoothly in toluene at or below room temperature (r.t.) in the presence of 1 and 2 (1 ∼ 4 mol %, respectively), went to completion within 1 h, and afforded syndiotactic-rich PMMA with molecular weight distribution (M_w/M_n) in the 1.1 ∼ 1.4 range. The number-average molecular weight (M_n) of the polymer was significantly higher than that calculated from the feed ratio of 1 to the monomer, indicating low initiating efficiency. Kinetic studies coupled with isolation of an intermediate species proved that the real monomeric species involved in both initiation and propagation was a complex of MMA with 2. The effects of the concentrations of 1, 2, and MMA as well as the temperature of polymerization were also examined. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3671–3679, 1999     

Reverse atom transfer radical polymerization of methyl methacrylate initiated by p‐chlorobenzenediazonium tetrafluoroborate

The controlled polymerization of methyl methacrylate (MMA) in bulk was initiated with p‐chlorobenzenediazonium tetrafluoroborate ( 1 ) and Cu(II) or Cu(I)/Cu(II)/N,N,N′,N″,N″‐pentamethyldietylene triamine (PMDETA) complex system at various temperatures (20, 60, and 90 °C). The proposed polymerization mechanism is based on the Meerwein‐type arylation reaction followed by a reverse atom transfer radical polymerization. In this mechanism, aryl radicals formed by the reaction with 1 and Cu(I) and/or PMDETA initiated the polymerization of MMA. The polymerization is controlled up to a molecular weight of 46,000 at 90 °C. Chain extension was carried out to confirm the controlled manner of the polymerization system. In all polymerization systems, the polydispersity index and initiator efficiency ranged from 1.10–1.57 to 0.10–0.21, respectively. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2019–2025, 2003     

Synthesis of styrene/methyl methacrylate copolymers by atom transfer radical polymerization: 2D NMR investigations

Copolymers of styrene and methyl methacrylate were synthesized by atom transfer radical polymerization using methyl 2‐bromopropionate as initiator and CuBr/N,N,N′,N′,N″‐pentamethyldiethylenetriamine as catalyst. Molecular weight distributions were determined by gel permeation chromatography. The composition of the copolymer was determined by ¹H NMR. The comonomer reactivity ratios, determined by both Kelen–Tudos and nonlinear error‐in‐variables methods, were r_S = 0.64 ± 0.08, r_M = 0.63 ± 0.08 and r_S = 0.66, r_M = 0.65, respectively. The α‐methyl and carbonyl carbon resonances were found to be compositionally and configurationally sensitive. Complete spectral assignments of the ¹H and ¹³C NMR spectra of the copolymers were done by distortionless enhancement by polarization transfer and two‐dimensional NMR techniques such as heteronuclear single quantum coherence and heteronuclear multiple quantum coherence. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2076–2085, 2006     

SET‐LRP of methyl methacrylate initiated with sulfonyl halides

Single electron transfer‐living radical polymerization (SET‐LRP) represents a robust and versatile method for the rapid synthesis of macromolecules with defined architecture. The present article describes the polymerization of methyl methacrylate by SET‐LRP in protic solvent mixtures. Herein, the polymerization process was catalyzed by a straightforward Cu(0)wire/Me₆‐TREN catalyst while initiation was obtained by toluenesulfonyl chloride. All experiments were conducted at 50 °C and the living polymerization was demonstrated by kinetic evaluation of the SET‐LRP. The process follows first order kinetic until all monomer is consumed which was typically achieved within 4 h. The molecular weight increased linearly with conversion and the molecular weight distributions were very narrow with M_w/M_n ～ 1.1. Detailed investigations of the polymer samples by MALDI‐TOF confirmed that no termination took place and that the chain end functionality is retained throughout the polymerization process. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2236–2242, 2010     

Novel catalyst system of MCl2/FeCl3·6H2O/PPh3 (M = Ni,Co, or Mn) for the atom transfer radical polymerization of methyl methacrylate

MCl₂ (M = Ni, Co, Sn, or Mn) and PPh₃ together acted as a catalyst for the radical polymerization of methyl methacrylate (MMA) in the presence of ethyl 2‐bromoisobutyrate as an initiator. The four systems all led to conventional radical polymerizations, which yielded polymers with a weight‐average molecular weight/number‐average molecular weight (M_w/M_n) ratio greater than 2.0 and became well controlled when a certain amount of FeCl₃·6H₂O was added. The polymerizations of MMA catalyzed by these four FeCl₃‐modified catalyst systems provided well‐defined polymers with low polydispersities (M_w/M_n < 1.28). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2625–2631, 2005     

Highly active methyl methacrylate polymerization catalysts obtained from bis(3,5‐dinitro‐salicylaldiminate)nickel(II) complexes and methylaluminoxane

The homopolymerization of methyl methacrylate was investigated with bis(salicylaldiminate)nickel(II) complexes, such as bis[3,5‐dinitro‐N(2,6‐diisopropylphenyl)salicylaldiminate]nickel(II) ( IIIa ) and bis[3,5‐dinitro‐N(phenyl)salicylaldiminate]nickel(II) ( IIIb ), and with methylaluminoxane (MAO) as an activator. In particular, the effect of the Al/Ni molar ratio on the catalytic activity and on the properties of the resulting poly(methyl methacrylate) (PMMA) was checked. The maximum activity was ascertained when an Al/Ni molar ratio equal to about 100 was used. However, the productivity of the catalytic systems was rather low. When the IIIa /MAO catalytic system was prepared under an ethylene atmosphere, an extremely high activity was observed, a productivity value of up to around 150,000 g of PMMA/(mol of Ni × h) being obtained, the highest ever found with nickel‐based catalysts. No appreciable presence of ethylene counits in the polymeric products was also ascertained. When the IIIb /MAO system was used, similar results were found, and high molecular weight PMMAs were obtained, despite the absence of bulky isopropyl substituents in positions ortho and ortho′ to the N‐aryl moiety of the salicylaldiminate ligand. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2117–2124, 2003     

Living radical graft polymerization of methyl methacrylate to polyethylene film with typical and reverse atom transfer radical polymerization

Nickel‐mediated atom transfer radical polymerization (ATRP) and iron‐mediated reverse ATRP were applied to the living radical graft polymerization of methyl methacrylate onto solid high‐density polyethylene (HDPE) films modified with 2,2,2‐tribromoethanol and benzophenone, respectively. The number‐average molecular weight (M_n) of the free poly(methyl methacrylate) (PMMA) produced simultaneously during grafting grew with the monomer conversion. The weight‐average molecular weight/number‐average molecular weight ratio (M_w/M_n) was small (<1.4), indicating a controlled polymerization. The grafting ratio showed a linear relation with M_n of the free PMMA for both reaction systems. With the same characteristics assumed for both free and graft PMMA, the grafting was controlled, and the increase in grafting ratio was ascribed to the growing chain length of the graft PMMA. In fact, M_n and M_w/M_n of the grafted PMMA chains cleaved from the polyethylene substrate were only slightly larger than those of the free PMMA chains, and this was confirmed in the system of nickel‐mediated ATRP. An appropriate period of UV preirradiation controlled the amount of initiation groups introduced to the HDPE film modified with benzophenone. The grafting ratio increased linearly with the preirradiation time. The graft polymerizations for both reaction systems proceeded in a controlled fashion. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3350–3359, 2002     

Atom transfer radical polymerization of methyl methacrylate at ambient temperature using soluble Cu(I) complex catalysts formed with mixed ligands of multidentate amines and halide ions

An Erratum has been published for this article in J Polym Sci Part A: Polym Chem (2004) 42(19) 5030 . The addition of soluble quaternaryammonium halides (QX) in catalytic amounts takes into solution CuX/pentamethyldiethylenetriamine (PMDETA) complex (X = Cl, Br) in methyl methacrylate (MMA). The soluble catalyst complex provided much better control of the polymerization of MMA at ambient temperature than did the insoluble catalyst formed in the absence of QX, with CuCl/PMDETA/Aliquat® 336 (AQCl) proving to be superior to the CuBr/PMDETA/Bu₄NBr catalyst system. The effect was independent of the size of the quaternaryammonium ion. Also, the presence of Cl in the catalyst–QX combination either as CuCl or as QCl was enough to give much better control than that provided by a wholly Br‐based system. Among the various initiators used, that is, ethyl 2‐bromoisobutyrate (EBiB), methyl 2‐bromopropionate (MBP), 1‐phenylethyl bromide (PEBr), and p‐toluenesulfonyl chloride (pTsCl), only EBiB gave a satisfactory result. With MBP and PEBr the initiation was slower than the propagation, whereas with pTsCl the initiation was very fast, so that instantaneous termination occurred. The living nature of the polymers was shown by block copolymer preparation. It has been suggested that some of the added halide ions entered into the coordination spheres of Cu(I) and Cu(II), leading to their improved solubility and stronger deactivation by the Cu(II) complex. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4132–4142, 2004     

Stepped association of comb‐like and stimuli‐responsive graft chitosan copolymer synthesized using ATRP and active ester conjugation methods

Herein, we report the synthesis of a comb‐like pH‐sensitive graft copolymer, poly[(2‐dimethylamino)ethyl methacrylate]‐graft‐chitosan, using atom transfer radical polymerization (ATRP) and active ester conjugation methods. The utilization of ATRP guaranteed the narrow molecular weight distribution of the side chains, which further led to the low polydispersity of the copolymer aggregates. The active ester reaction took place in the mild and homogeneous solutions, and the graft ratio reached 58%. The pH‐responsive association behavior of the graft copolymer in aqueous solution was examined by potentiometric titration, laser light scattering, surface tensiometry, and transmission electron microscopy. Because of the difference in proton dissociation between the amine groups of chitosan and DMAEMA segments, the copolymer exhibited the different conformations with pH variation: random coils at pH ∼ 4, core‐shell structured micelles at pH 5–6, double‐layered hard spheres at pH ∼ 7, and larger aggregates at pH ∼ 8. The beneath mechanism cause the microstructure changes as a function of pH was discussed. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6682–6692, 2009     

Cu(II)‐Mediated ATRP of MMA by Using a Novel Tetradentate Amine Ligand with Oligo(ethylene glycol) Pendant Groups

A novel tetradentate amine ligand namely N,N,N′,N″,N‴;,N‴;‐hexaoligo(ethylene glycol) triethylenetetramine (HOEGTETA) was employed in the homogenous ATRP of MMA in anisole using CuBr and CuBr₂ as the catalyst and ethyl 2‐bromoisobutyrate (EBiB) as an initiator. The effect of the polymerization temperature and the various ratios of Cu(I) to Cu(II) were investigated in detail. Moreover, we demonstrated the ATRP of MMA by using only Cu(II) in the absence of any free radical initiator, reducing agent, or air. The ATRP of MMA with the use of only Cu(II) and HOEGTETA or N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) resulted in well‐defined PMMA.

     

Reverse atom transfer radical solution polymerization of methyl methacrylate under pulsed microwave irradiation

The reverse atom transfer radical polymerization (RATRP) of methyl methacrylate (MMA) was successfully carried out under pulsed microwave irradiation (PMI) at 69 °C with N,N‐dimethylformamide as a solvent and with azobisisobutyronitrile (AIBN)/CuBr₂/tetramethylethylenediamine as an initiation system. PMI resulted in a significant increase in the polymerization rate of RATRP. A 10.5% conversion for a polymer with a number‐average molecular weight of 34,500 and a polydispersity index of 1.23 was obtained under PMI with a mean power of 4.5 W in only 52 min, but 103 min was needed under a conventional heating process (CH) to reach a 8.3% conversion under identical conditions. At different [MMA]₀/[AIBN]₀ molar ratios, the apparent rate constant of polymerization under PMI was 1.5–2.3 times larger than that under CH. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3823–3834, 2002     

Atom transfer radical polymerization of n‐butyl methacrylate in an aqueous dispersed system: A miniemulsion approach

Ultrasonication was applied in combination with a hydrophobe for the copper‐mediated atom transfer radical polymerization of n‐butyl methacrylate in an aqueous dispersed system. A controlled polymerization was successfully achieved, as demonstrated by a linear correlation between the molecular weights and the monomer conversion. The polydispersities of the polymers were small (weight‐average molecular weight/number‐average molecular weight < 1.5). The influence of several factors, including ultrasonication, the amount of the surfactant, and the nature of the initiator, on the polymerization kinetics, molecular weight, and particle size was studied. The polymerization rate and molecular weights were independent of the number of particles and only depended on the atom transfer equilibrium. The final particle size, however, was a function of all the parameters. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4724–4734, 2000