Methyl acrylate polymerization with ATRP

The various acrylates polymerized by ATRP are shown in Table II. Poly(methyl acrylate) was synthesized with molecular weights up to 75,000 with excellent control (75). Molecular weights increased linearly with conversion, the polydispersity at 90% conversion was... 

For well-controlled arm number of the star polymers, an efficient approach is the use of multifunctional initiators [157,158]. For instance, the four-armed initiator, NLI-1, which was prepared by the condensation reaction of the hydroxy groups in C(CH20CH2CH2CH20H)4 with a-bromoisobutyric acid, was used in the ATRP of (2,2-dimethyl-l,3-dioxoIane-4-yl)methyl acrylate (DMDMA) with CuBr/bpy as catalyst. After isolation from the polymerization system, four-armed poly(DMDMA)s, such as NLI-2 with Mw/Mn = 1.28—1.41 were obtained, and used in the successive ATRP of MMA, giving star-block copolymers NLB-3. It is known that the cycloacetal ring is unstable in acidic conditions, so the hydrolysis of the block copolymer NLB-3 was accomplished in a 1N HCl aqueous solution to give the amphiphilic star-block copolymer structure NLB-4 as shown in Scheme 3.37 [159]. 

CuPFg, complexed with two molecules of pyridine, is an efficient system for ATRP of styrene and methyl acrylate [8]. Notably, ligand exchange occurring with mixed systems such as CuBr/R-Q was not observed due to the noncoordinating nature of CuPF. For styrene polymerization employing phenylethylchloride as the alkyl halide, better control of the molecular weight and linear kinetic behavior was observed. The rates of polymerization were enhanced in methyl acrylate polymerization. 

Substituted terpyridine, 4,4, 4"-tris(5-nonyl)-2,2 <5, 2"-terpyridine (tNtpy), is a planar tridentate ligand that was successfully used in homogeneous ATRP of methyl acrylate and styrene [79]. Polymerization of both monomers was controlled and the resulting polymers had relatively low polydispersities (MJMn < 1.2). Similarly to PMDETA, the typical ligand to copper halide ratio used in the polymerization was 1 1. Terpyridine and its derivatives are expected to form tetra-coordinated complexes with copper in which the fourth coordination sphere is occupied by a monodentate ligand (Br-, Cl , solvent, monomer, etc.). Although,... 

A one-pot synthesis of telechelic and semitelechelic poly(alkyl acrylates) with unsaturated end groups has been developed by Bielawski et al. [1]. ATRP of methyl acrylate or -BA was initiated with either ethyl cy-bromomethyl-acrylate or methyl dichloro acetate, as a monofunctional or a difunctional initiator, respectively, and was mediated with various Cu-amine complexes. Addition of excess ethyl 2-bromomethylacrylate was found to immediately quench the polymerization, but also to insert 2-carbethoxyallyl moieties at the ends of the polymer chains (Scheme 24). Thus, the synthesis of telechelic poly(alkyl acrylates) with unsaturated end groups has been accomplished, with very good functionality (f 2) (Scheme 24). 

Another type of bJock-copolymer was obtained by conversion of living ROMP into controlled atom-transfer radical polymerization (ATRP). The approach involves the termination of a living ROMP polymer with a />bromomethylbenzaldehyde. This prepolymer may be Initiated using CuBr/2,2-dipyridyl and used for bJock-copolymer formation with styrene and methyl acrylate (Scheme 48). Finally, the preparation of 7-oxabicyclo[2.2.1]hept-2-ene-5,6-dimetha-nol-derived ROMP polymers and their use for the preparation of 7V-alkyl-3-aza-8-oxabicyclo[3.2.1]octane-... 

Hence, the insensitivity to addition sequence for styrene and (AA) monomers makes it relatively easy to form (PS-fc-PAA), (PS-fc-PAA-fc-PS), and (PAA-Z -PS-Z -PAA) di- and tiiblock copolymers. However, when AN and MMA are involved, the poly(acrylonittile) block must be formed first, i.e., second monomer addition should be in the order shown in the preceding text. Unlike NMP methods, the use of ATRP presents no major problems when preparing block copolymers containing acrylates and methacrylates. Triblock (ABC) copolymers can be prepared by starting with a bromine-terminated polystyrene macroinitiator to polymerize Z-butyl acrylate, followed by methyl acrylate or methyl methacrylate using a CuBr/pentamethyl diethylene triamine catalyst. 

Currently, ATRP is the most widely used controlled radical polymerization in anion-to-radical transformation methodology. The first such example was reported by Acar and Matyjaszewski [61], and utilized for the preparation of AB- and ABA-type block copolymers. The macroinitiators, PSt and polyisoprene-b-polystyrene (PIP-fc-PSt) containing 2-bromoisobutyryl end groups were prepared by living anionic polymerization and a suitable termination agent. These polymers were then used as macroinitiators for ATRP to prepare block copolymers with methyl acrylate (PSt-b-PMA), butyl acrylate (PSt-b-PBA), methyl... 

Vinyl-ftmctionalized poly(methacrylate) has also been prepared by the reaction of allyltri-n-butylstannane. The reaction of organic halides with allyltri-n-butylstannane was first discovered by Keck and Migita. " ° Methyl acrylate was polymerized in bulk by ATRP to 93% conversion, upon which benzene and allyltri-n-butylstannane (3 molar equivalents) were added to the reaction mixture and allowed to react for 8 h. After purification, the presence of the vinyl end group was confirmed by NMR and ESI. The degree of functionalization was not reported. 

RAFT polymerizations with this iniferter of iV-butyl acrylate and styrene yielded polymers with M. / Mn equal to 1.15 and 1.16 respectively. Polymerization of methyl methacrylate, however, yielded a polymer with a broad Mw/M ratio. On the other hand, polymerization in the presence of CuBr/TMPA by ATRP exclusively through the bromine chain ends yielded a polymer with narrow ratio [282],... 

In a later work, copolymers of PVC with various grafted chains like polyCbutyl acrylate), PMMA, PS, and poly(methyl acrylate) were synthesized (43). The backbone was a random copolymer of vinyl chloride and vinyl acetate. The carbonyl substituted alkyl halide groups were used as the initiator for the polymerization of these monomers by ATRP. 

Biedron and co-workers (39) reported heterogeneous ATRP in [BMIMJPFe. Alkyl acrylates (methyl, butyl, hexyl, and dodecyl) are either soluble, partly soluble, or completely insoluble in this RTIL depending on the length of the alkyl substituent. For the heterogeneous systems, the alkyl acrylate formed an upper monomer phase while the CuBr/pentamethyldiethylenetriamine (PMDETA) catalyst remained in the lower RTIL phase. Methyl acrylate (MA) and poly(methyl acrylate) (PMA) are miscible with [BMIMJPFe and form a homogeneous polymerization system, therefore, all reactions proceed in one phase. For the three other acrylates, the growing macromolecular chains react with the monomer at the... 

Results from kinetic studies of ATRP under homogeneous conditions for styrene (Matyjaszewski et al., 1997), methyl acrylate (Davis et al., 1999), and methyl methacrylate (Wang et al., 1997) indicate that the polymerization rate is rst order with respect to monomer, initiator, and Cu(I) complex concentrations. These observations are in agreement with Eq. (11.20). 

Acrylic acid cannot be polymerized by ATRP which is sensitive to the presence of acids. Moreover, since many of the ligand systems utilized are nitrogen-based, protonation of the nitrogen may occur, disrupting its coordination to the metal center. The solution to this problem is to polymerize protected monomers, followed by a deprotection step to generate the polyacid. Thus Davis and Matyjaszewski (2000) synthesized poly(acrylic acid) (PAA) via hydrolysis of poly(tert-butyl acrylate) (PrBA), which, in turn, was obtained by ATRP of iBA using a CuBr/PMDETA catalyst system in conjunction with an alkyl bromide, such as methyl-2-bromopropionate (MBrP), as the initiator. The monomer conversion was 93% after 320 min at 60°C. 

Results from kinetic studies of ATRP for styrene, methyl acrylate, and methyl methacrylate under homogeneous conditions indicate that the rate of polymerization is rst order with respect to the concentrations of the initial components, namely, monomer, initiator, and Cu(I)/ligand complex. Derive a rate law that is consistent with this observation. State the assumptions made in the derivation. Predict the variation of monomer conversion with time based on the rate law. Analyze the effect of Cu(II) on the polymerization and the conditions under which living/controlled polymerization will proceed. 

A bromine-terminated monofunctional poly(rerr-butyl acrylate) resulting from ATRP of rBA catalyzed by the CuBr/At, At,At, iV, lV"-pentamethyldiethylenetriamine (PMDETA) system (initial mole concentration ratios tBA methyl bromopropionate (MBrP) CuBr PMDETA CuBr2 = 50 1 0.5 0.525 0.025, 25% acetone, 60°C conversion = 96% after 6.5 h) was used as macroinitiator for block copolymerization with styrene (St) with the initial mole concentration ratios of St P(rBA) CuBr PMDETA = 100 1 1 1 at 100°C (conversion 94%). The monofunctional bromo-terminated copolymer P(rBA)-A-P(St) formed was subsequently used as a macroinitiator for a further copolymerization with methyl acrylate (MA). The polymerization was also catalyzed by CuBr/PMDETA (initial concentration ratios MA P(rBA-i>-P(St) CuBr PMDETA = 392 1 1 1), under high dilution in toluene and reached 23% monomer conversion after 3.5 h at 70°C. The experimental molecular weight (M ) of the resulting triblock copolymer P(tBA)-fo-P(St)-fr-P(MA) was 24,800 with a PDI = 1.10. Calculate the theoretical M to compare with the experimental value. 

While ATRP of methyl acrylate was reported only for the copper catalyst system [290-292] methyl meth(acrylate) was also polymerized with copper [290,293 295], ruthenium/aluminum alkoxide [296,297], iron [298,299] and nickel [300 303] eatalyst systems (Table 9). Thereby, it must be noted that in principle, the ruthenium-based system proposed by Sawamoto et al. requires the addition of Lewis acids, e.g., Al(0- -Pr)3 [297]. Recent investigations showed, that the half-metallocene -type ruthenium(II) chloride Ru(Ind)Cl(PPh3)2 (Ind = indenyl) led to a fast and well controlled polymerization even without the addition of Al(0- -Pr)3, whereas in case of a polymerization with Ru(Cp)Cl(PPh3)2 (Cp = cyclopentadienyl), the addition of Al(0-z-Pr)3 is necessary. The activity of Ru(II)-catalysts decreases in the order Ru(Ind)Cl(PPh3)2 > RuCl2(PPh3)2 > Ru(Cp)Cl(PPh3)2 [304]. 

Carboxylic acid groups may deactivate ATRP initiators however, carboxylic acid-containing monomers can be polymerized via ATRP by carefully adjusting the solution pH [69]. Matyjaszewski et al. reported the controlled copolymerization of DMAEMA with methyl methacrylate, methyl acrylate, and styrene yielding pH-responsive amphiphilic block copolymers [70]. Aqueous RAFT... 

By this chemistry, polymers with one amine end group as well as a,co-diamine-functionalized polymers can be used to prepare AB or ABA copolymers, respectively. The method gives copolymers with well-controlled polypeptide segments. Furthermore, no unreacted homopolymers or homopolypeptides could be detected. Several examples of the polymer B block have been reported poly(octenamer) prepared by acylic diene metathesis polymerization [67], poly(methyl acrylate) prepared by atom transfer radical polymerization (ATRP) [70], poly(ethylene glykol) PEG, and PDMS [68]. The method was expanded for the synthesis of... 

Reversible addition-fragmentation chain transfer polymerization (RAFT) polymerization of methyl acrylate was combined with cationic polymerization of THF to synthesize comb copolymers. Asymmetric star block copolymers based on polystyrene (PS), PTHF, and PMMA were synthesized by a combination of CROP and redox polymerization methods. Miktoarm star polymers containing poly(THF) and polystyrene arms were also obtained by combining CROP and ATRP methods. Another approach for the synthesis of block copolymers... 

Indeed, it is now possible to extend the range of monomers incorporated into a block copolymer by conducting sequential RAFT and ATRP polymerizations employing a dual functional bromoxanthate iniferter (initiator-transfer agent-terminator). Poly(vinyl acetate)-1 -PS, poly(vinyl acetate)- 7-poly (methyl acrylate), and poly(vinyl acetate)- -PMMA block copolymers with low polydispersity 1.25) were prepared... 

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