Complex macroinitiators

Block copolymers of (R,S)-(3-butyrolactone and eCL have been synthesized by combining the anionic ROP of the first monomer with the coordinative ROP of the second one (Scheme 15) [71]. The first step consisted of the synthesis of hydroxy-terminated atactic P(3BL by anionic polymerization initiated by the alkali-metal salt of a hydroxycarboxylic acid complexed with a crown ether. The hydroxyl end group of P(3BL could then be reacted with AlEt3 to form a macroinitiator for the eCL ROP. 

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,... 

Using of Terminal Silanolate Function for Building More Complex Macromolecular Structures by Macroinitiator and Macromonomer Techniques or by Sequential Copolymerization... 

Recently diblock copolymers of PEG and ionic segments were prepared by atom-transfer radical polymerization of methacrylic aminoester using a monofunctionalized PEG macroinitiator and then subsequent quaternization. Like others [60] these polymers form so called polyion complex micelles by electrostatic interaction with oppositely charged molecules (e.g. drugs, oligonucleotides), where the PEG block acts as a steric stabilizer [67]. 

The self-condensing copper-catalyzed polymerization of macromonomer of poly(tBA) with a reactive C—Br bond (H-6) affords hyperbranched or highly branched poly(tBA).447 Copolymerization of H-1 and TV-cyclohexylmaleimide induced alternating and self-condensing vinyl polymerization.448 The residual C—Cl bond was further employed for the copper-catalyzed radical homopolymerization of styrene to give star polymers with hyperbranched structures. Hyperbranched polymers of H-1 further serve as a complex multifunctionalized macroinitiator for the copper-catalyzed polymerization of a functional monomer with polar chromophores to yield possible second-order nonlinear optical materials.325... 

Matyjaszewski et al. demonstrated that living ring opening metathesis polymerization (ROMP) could also be combined with ATRP to produce novel block copolymers [292]. ROMP of norbornene (NB) and dicyclopentadiene (CPD) were performed using an Mo-alkylidene complex, followed by reaction with p-(bro-momethyl) benzaldehyde to generate a benzyl bromide terminated polymer capable of being used as a macroinitiator for ATRP (Scheme 41). 

This can act as a macroinitiator that can be nsed to polymerize MMA, using a niekel bromide complex eatalyst (NiBrjlPPhjlj) thereby yielding a diblock copolymer (PECL-b-PMMA). 

Hydroxy-terminated PEG is readily transformed into ATRP macroinitiators by conversion of the hydroxyl groups to terminal halide units followed by reaction with a transition metal/ligand complex, and used to form diblocks with several monomers, including the sodium salt of methacrylic acid. 

The synthesis of an ampholytic block copolymer, namely PMAA-PDEAEMA, carrying carboxylic and tertiary amino side groups, has been also realized by ATRP, as has been reported by Tam and coworkers [15]. Initially, the synthesis of the tert-butyl protected PMAA block was performed using p-toluenesulfonyl chloride as an initiator and CuCl complexed with N,N,N ,N ,N ,N -hexamethyltriethylenetetraamine as a catalyst in 50 vol % anisole at 90 °C. The obtained polymer was used as the macroinitiator for the subsequent polymerization of the second monomer, DEAEMA, imder similar reaction conditions. Figure 3. The resulted copolymer was subjected to selective hydrolysis, imder acidic conditions, for removal of the tert-butyl protecting group. 

N-vinylpyrrolidone) (PNVP) and amphiphilic PVA-h-PAN [33, 48). Hydrolysis of both the esters and the nitrile groups of the PVAc-h-PAN copolymers paved the way to a well-defined, pH-sensitive PAA-h-PVA compound [48, 50). Despite the low polyolefin content of the final material, 1-octene was used successfully as the comonomers of VAc in the block, and statistical radical polymerization processes were carried out in the presence of cobalt complexes [51]. Moreover, the resumption of styrene polymerization from a PVAc-Co(acac)2 macroinitiator was also considered, which led to the expected PVAc-b-polystyrene (PS) copolymer unfortunately, however, a poor control of the styrene block was observed in this case [52]. 

Bromo-functionalized PTHFs obtained this way were used as initiators in the ATRP of styrene, MMA, and MA to yield AB- and ABA-type block copolymers. Notably, in the case of styrene and MA, the formation of triblock copolymers was significantly slower. It was also reported [79] that PSt with chlorine termini, synthesized by hving cationic polymerization without any additional reaction, was an efficient macroinitiator for living ATRP of styrene, MMA, and MA (Scheme 11.20). With some variations in the initiator design, more complex structures such as block, graft, and miktoarm-starblock copolymers having PTH F [80-85] chains as the cationic segment were synthesized. 

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