Bromine terminator

The reaction sequence used to synthesize these flexible systems involved four steps which are outlined in Figure 1. The first of these was an aromatic nucleophilic substitution, a polymer forming reaction in which 4,4 -dichlorodiphenyl sulfone reacts with various diols. The second step, an Ullmann ether reaction, gives bromine terminated products in which the bromines can be replaced by ethynyl end groups in the final stages. 

Cohen YS, Vilan A, Ron I, Cahen D (2009) Hydrolysis improves packing density of bromine-terminated alkyl-chain, silicon-carbon monolayers linked to silicon. J Phys Chem C 113 6174-6181... 

These results indicate that if polydienes and similar polymers can be prepared quantitatively with tertiary amine terminal groups, then they can be combined with other halogen functional polymers using established techniques to create interesting new block copolymer systems. For example, consider the reaction between telechelic pyridine terminated polybutadiene and monofunctional bromine terminated polystyrene (equation 4) -the latter has been prepared in 95% yield. >it The product would be an ABA... 

Another route to bromine terminated polymers has been to react anionic polymers with halogenated terminating agents such asa,[Pg.72]

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... 

The reaction of bromine-terminated polymer with ammonia was also investigated as a potential route to amine-functionalized polymer. The reaction of PMMA-Br with a... 

Eventually, PSt-b-PTHF was synthesized by the reaction of the bromine-terminated PSt with a suitable silver salt in the presence of THE (Scheme 27). 

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. 

The bromine-terminated oligo(ethenylene)s (193) underwent a multi-step SCSC dimerization to afford (194) that involved the eleavage of a C-Br bond with unusually large atom displaeements. ... 

Azido-terminated polymers can also be used in dick chemistry modifications with acetylene derivatives to incorporate various functional groups. Polymers with phosphonium end-groups were prepared from bromine-terminated PS or polyacrylates and BusP. Mercapto-terminated PS was prepared by the reaction of the corresponding bromo-compound with either thiodimethylformamide or thiourea followed by reaction with a nucleophile. ... 

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