Copper polymer-capped

Almost all metal-catalyzed living polymerizations give polymers capped with halogens that are stable after the usual workup. These terminal halogens would be undesirable, because they may lower the polymer s thermal stability. Dehalogenation by tribu-tyltin hydride (EC-15) is of importance in this respect and effectively works for the bromide terminals in polystyrene, PMMA, and poly(MA) in the presence of copper catalysts.277... 

Gouanve F, Schuster T, Allard E, Meallet-Renault R, Larpent C (2007) Fluorescence quenching upon binding of copper ions in dye-doped and ligand-capped polymer nanoparticles a simple way to probe the dye accessibility in nano-sized templates. Adv Funct Mater 17 2746-2756... 

Block copolymers may also be made by condensation polymerization. Elastomer fibers are produced in a three-step operation. A primary block of a polyether or polyester of a molecular weight of 1000-3000 is prepared, capped with an aromatic diisocyanate, and then expanded with a diamine or dihydroxy compound to a multiblock copolymer of a molecular weight of 20,000. The oxidative coupling of 2,6-disubstituted phenols to PPO is also a condensation polymerization. G. D. Cooper and coworkers report the manufacture of a block copolymer of 2,6-dimethyl-phenol with 2,6-diphenylphenol. In the first step, a homopolymer of diphenylphenol is preformed by copper-amine catalyst oxidation. In the second step, oxidation of dimethylphenol in the presence of the first polymer yields the block copolymer. 

Allyltri-n-butylstannane (EC-2) similarly terminates the copper-catalyzed polymerization of MA to give allyl-functionalized polymers via elimination of the stannyl group accompanying the bromine originated from the dormant polymer terminal.346 Allyl a -end PMMA was obtained also by the copper-catalyzed reaction between allyl bromide (EC-3) and the isolated bromine-capped PMMA, although the functionalization was 57%.226 Another allyl derivative (EC-4) similarly leads to methacrylate-based macromonomers quantitatively in the presence of Cu(0).347... 

The ABA-type block copolymers B-86 to B-88 were synthesized via termination of telechelic living poly-(THF) with sodium 2-bromoisopropionate followed by the copper-catalyzed radical polymerizations.387 A similar method has also been utilized for the synthesis of 4-arm star block polymers (arm B-82), where the transformation is done with /3-bromoacyl chloride and the hydroxyl terminal of poly(THF).388 The BAB-type block copolymers where polystyrene is the midsegment were prepared by copper-catalyzed radical polymerization of styrene from bifunctional initiators, followed by the transformation of the halogen terminal into a cationic species with silver perchlorate the resulting cation was for living cationic polymerization of THF.389 A similar transformation with Ph2I+PF6- was carried out for halogen-capped polystyrene and poly(/>methoxystyrene), and the resultant cationic species subsequently initiated cationic polymerization of cyclohexene oxide to produce... 

Combination of a living ionic polymerization and a metal-catalyzed radical polymerization also leads to comb polymers, where both the molecular weights of the arm and main-chain polymers are well controlled. PMMA with poly(vinyl ether) arm polymers of controlled molecular weights (C-l) were prepared by the copper-catalyzed radical polymerization of methacrylate-capped macromonomers carrying a poly-(isobutyl vinyl ether), which were obtained by living cationic polymerization with a methacryloxy-capped end-functionalized initiator.428 Comb polymers with... 

Armes et al. have intensively studied the aqueous ATRP of various monomers. Using CuBr/bpy as a catalyst, methacrylic acid polymerization has been shown to be possible in aqueous media at pH values between 6 and 9 [200]. The polymerization occurs very slowly (80% conversion after 21 h at 90 °C, [monomer] [initiator] [catalyst] = 28 1 1) yielding polymers with low molecular weight (M = 2.9xl0 g mol ) and a polydispersity of Mw/Mn = 1.3. This is probably due to a loss of catalytic species occurring from the competitive coordination of carboxylic acids to the copper centers, as mentioned for the case of acrylic acid. The choice of pH is important at pH <6, protonation of the bipyridyl ligand occurs, resulting in loss of control. The choice of initiator is equally important the polymerization is only controlled when the methoxy-capped macroinitiator 46 is used. 

K., Mugisawa, M., and Ohnishi, K. (2007) Preparation of novel cross-linked fluoroalkyl end-capped adamantane cooligomer/copper nanocomposites. European Polymer Journal, 43,... 

The approaches to polymer-stabilized copper nanomaterials can be divided into three main classes (i) the so-called polyol process (ii) soft-template processes in which the polymer is employed (either as such or in combination with other capping agents), aiming exclusively at stabilization of the Cu phases and (iii) dendrimer-encapsulation. 

The method is sufficiently versatile that methacrylates, acrylonitriles, dienes, and styrenes all are copolymerized. The proposed mechanism for ATRP is shown in the scheme below. The figure shows three possible activities for the radical (1) dormant—most of the time the radical is capped and unreactive, and (2) polymer formation—the radical is active and the halogen is complexed with the copper enabling the insertion of monomer. This state is short lived enough that side reactions and termination are unlikely. Finally (3) unwanted reactions such as termination may occur. Again the chance of these latter reactions are minimized enough that the polymerization can be considered living, that is, without termination. 

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