Poly bromine terminated

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. 

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. 

Terminally brominated PE as PE macroinitiator can be produced by other methods. It has been reported that vinyl terminated PE produced by a bis(phenoxy-imine)metal complex and MAO catalyst system (Mn = 1800, Mw/Mn = 1.70) was converted to terminally 2-bromoisobutyrate PE through the addition reaction of 2-bromoisobutyric acid to the vinyl chain end. Polyethylene-Wodc-poly( -bulyl acrylate) (PE-fo-PnBA) from terminally brominated PE by ATRP procedure has also been produced [68]. It was reported that degenerative transfer coordination polymerization with an iron complex can be used to prepare terminally brominated PE as a macroinitiator [69]. A Zn-terminated PE prepared using an iron complex and diethylzinc,... 

PP-b-PMMA (Mn = 22220, Mw/Mn = 1.14) was produced by CRP via another route. Terminally vinyl PP (Mn = 3100, Mw/Mn = 1.45, isotactic-ity = 32%) prepared using a zirconocene catalyst was converted to terminally brominated PP via PP-SiH prepared by hydrosilylation [70]. The resulting PP-b-PMMA was purified by extraction of unreacted PP with diethyl ether. Poly(ethylene-co-butene)-bZocfc-poly(methyl methacrylate) (EBR-b-PMMA) was synthesized through the bromination of terminally hydroxy-lated EBR (Mw = 3600 g/mol, Mw/Mn = 1.05), which was commercially available [71]. An atactic PP/PMMA had been synthesized by a combination of metallocene catalyses, Cp2ZrCl2 and Me2Si(CpMe4)(.W-f-Bu)TiCl2, and ATRP [72]. 

Other types of functionalized poly(3-alkylthiophene)s can be prepared in order to obtain polymeric materials with different chemical, optical, and electronic properties and different solubilities. The organozinc route has been used to synthesize poly thiophenes bearing a phosphonic ester functionality or functional groups such as bromine, ester, alcohol, and acetal-protected aldehyde as terminal groups of C-3-substituents, as illustrated in Scheme 11 [76]. 

Ni and his colleagues prepared block copolymers of PEEP-l -poly[2-(dimethylamino)ethyl methacrylate] (PEEP-b-PDMAEMA) (7) via the combination of ROP and ATRP. The PEEP block terminating with bromine (PEEP-Br) was first prepared by ROP of EEP using 2-hydroxyethyl 2-bromoisobu-tyrate as a bifanctional initiator and Sn(Oct)2 as the catalyst. ATRP was then used to polymerize DMAEMA monomers in a methanol/water mixture with PEEP-Br as the macroinitiator, resulting in diblock copolymers of PEEP-b-PDMAEMA. These block copolymers are expected to have potential applications in gene therapy. 

After the development of catalyst-transfer condensation polymerization of polythiophene, the block copolymer of polythiophene and poly(alkyl acrylate) was prepared more easily. Vinyl-terminated polythiophene was first prepared. The vinyl group was converted to the 2-hydroxyethyl group by hydroboration, followed by esterification with 2-bromopropionyl bromide to give a macroinitiator for ATRP (Scheme 50) [142]. The allyl-terminated polythiophene was also converted to a macroinitiator for ATRP, which led to block copolymers of polythiophene and poly (aUcyl methacrylate) [143] or poly(acrylic acid) [144]. This allyl-terminated polythiophene has a bromine atom at the other end, which has an adverse effect on the purity of block copolymers prepared by ATRP. Hawker, Kim, and coworkers reported that replacement of the bromine with a phenyl group, followed by functionalization of the allyl group for the ATRP initiator unit, allowed access to narrower molecular weight distribution diblock copolymers of polythiophene and ATRP-derived vinyl block [145]. 

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