Macroinitiators bromine

It has been reported by Matsugi et al. that PE-fo-PMMA can be synthesized by ATRP techniques with a CuBr and an N,N,N/,N//,N//-pentamethyldiethyl-enetriamine (PMDETA) catalyst system, or with a RuCl2(PPh3)3 and dibuty-lamine catalyst system. They have used terminally hydroxylated PE, produced by the metallocene-catalyzed polymerization of ethylene with allyl alcohol as starting material. The PE macroinitiator was converted to terminally bromi-nated PE by the bromination of obtained PE-OH with bromo-isobutyric bromide (Fig. 11) [67]. 

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,... 

The copolymer of ethylene withp-MS was available as a PE macroinitiator. PE-g-Br, which works as a PE macroinitiator for ATRP, was prepared from PE-g-MS by bromination with NBS [78], and PE-g-Br can be used to prepare PE-g-PMMA, PE-g-PS and PE-g-PnBA. 

Matyjaszewski et al. showed, however, that when a Cu(I)Br catalyst was used in conjunction with bromine-based initiators for a similar system (St/tBA), the polymerizations were well controlled and chain extension in either direction was possible [194]. This is different from the nitroxide system where chain extension of a pSt macroinitiator with acrylate monomers resulted in low blocking efficiency [71 ]. AB and ABA type block copolymers were prepared using monofunctional and difunctional ptBA or pSt macroinitiators. Deprotection of the ferf-butyl esters in these AB block copolymers afforded amphiphilic block copolymers capable of being used as surfactants for emulsion polymerizations [194,195]. 

Kubisa et al. also used hydroxy-functional PEG after reaction with 2-bromo-propionyl bromide as an ATRP macroinitiator [228]. Their goal, however, was to polymerize ferf-butyl acrylate, rather than St, then to hydrolyze the esters to acid functionality and study the cation binding properties of the doubly amphiphilic block copolymers. They utilized a CuBr/PMDETA catalyst system for the polymerization and, although the macroinitiator was completely consumed, MALDI-TOF analysis indicated that bromine was replaced with a hydrogen at... 

The h rbranched polymer with bromine end groups was also used as a macroinitiator for the ATRP of n-butyl ac late. A multi-armed star polymer with a hypeibranched core was obtained wiUi, against linear polystyrene standards, M,=l 10,000 and NVMb=2.6. ... 

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. 

In addition, Liu and Chen prepared a MWCNT-based macroinitiator through an addition reaction between the ATRP initiator 1-bromoethylben-zene or the macroinitiator of bromine-terminated PS, and CNTs with CuBr/ PMDETA as the catalyst system at 80 °C for 24 h. Further ATRP of styrene or NIP A Am on the functionalized CNTs afforded PS-grafted CNTs or V-shaped amphiphilic polymer PS-PNIPAAm-grafted CNTs which showed Janus... 

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