ATRP methods

Star polymers are a class of polymers with interesting rheological and physical properties. The tetra-functionalized adamantane cores (adamantyls) have been employed as initiators in the atom transfer radical polymerization (ATRP) method applied to styrene and various acrylate monomers (see Fig. 21). 

Controlled free-radical polymerization methods, like atom-transfer radical polymerization (ATRP), can yield polymer chains that have a very narrow molecular-weight distribution and allow the synthesis of block copolymers. In a collaboration between Matyjaszewski and DeSimone (Xia et al., 1999), ATRP was performed in C02 for the first time. PFOMA-/)-PMMA, PFOMA-fr-PDMAEMA [DMAEMA = 2-(dimethylamino)ethyl methacrylate], and PMMA-/)-PFOA-/)-PM M A copolymers were synthesized in C02 using Cu(0), CuCl, a functionalized bipyridine ligand, and an alkyl halide initiator. The ATRP method was also conducted as a dispersion polymerization of MMA in C02 with PFOA as the stabilizer, generating a kine-... 

Kaneko et al. have reported the preparation of EPR macromonomers, which is useful to synthesize PMMA-g-EPR graft copolymers [106]. Graft copolymers possessing a poly(methacrylate) backbone and EPR branches were successfully synthesized by the copolymerization of EPR macromonomers with MMA. Methacryloyl terminated EPR, which were EPR macromonomers, were prepared by the sequential end functionalization of EPRs with vinylidene end group via hydroalumination, oxidation, and esterification (Fig. 20). The ATRP method can be used for the copolymeriza-... 

Furthermore, by using the ATRP method with a tetrafunctional initiator, the star copolymers consisting of four PMMA-g-EPR graft copolymer arms were also synthesized (Fig. 22). These unique topologies of the obtained copolymers can be confirmed by GPC measurement and NMR analysis. From TEM observation, the morphologies of these graft and star copolymers were remarkably altered by changing EPR branch number and the structure of the... 

On the other hand, the PMMA-g-EPR graft copolymers using the FRP method with AIBN showed a different morphology and thermal property from those after using the ATRP method, leading to the fact that the ATRP method is preferable compared to FRP method for the purpose of preparing well-defined macromolecular structures. Poly(EPR) can also be prepared by the free radical polymerization with AIBN [107]. 

The controlled emulsion polymerization of styrene using nitroxide-mediated polymerization (NMP), reversible addition-fragmentation transfer polymerization (RAFT), stable free radical polymerization (SFR), and atom transfer radical polymerization (ATRP) methods is described. The chain transfer agent associated with each process was phenyl-t-butylnitrone, nitric oxide, dibenzyl trithiocarbonate, 1,1-diphenylethylene, and ethyl 2-bromo-isobutyrate, respectively. Polydispersities between 1.17 and 1.80 were observed. 

Scheme 9. Copolymers formed using ATRP methods [114]...

Table 5. Summary of methacrylate containing block copolymers prepared using ATRP methods ...

Scheme 51. Illustration of growing pSt-ptBA block copolymers from a silicon surface using ATRP methods and conversion to pSt-pAA [328]...

The ARGET ATRP method was chosen for extension of PSt macroinitiator with /BA. This technique provides higher control over the polymerization of acrylates than ICAR ATRP (13, 23). It uses Sn(EH)2 or other non-radical... 

Besides the ATRP method, other controlled radical polymerization techniques such as reversible addition/fragmentation chain transfer polymerization (RAFT) (Zhang et al., 2007) and nitroxide-mediated polymerization (NMP) (Yoshida and Ohta, 2005), have also been explored to synthesize azo BCs. 

Scheme 12.3 Preparation of a PEO-based azo triblock copolymer by a modified ATRP method. Source Reproduced from Yu et al., 2005c.

PEG-based star copolymers bearing cationic cores were prepared by Cho et al. using the arm-first ATRP method (Scheme 3.7). ° The PEG-based macromonomer was polymerized with DMAEMA in the presence of a degradable crosslinker to obtain well-defined star-shaped nanoparticles of 120 kDa with degradable and cationic cores. The PEG-based star-shaped... 

Scheme 11.12 Synthesis of block copolymers by combination of living anionic polymerization and ATRP methods.

Scheme 11.21 Synthesis of ABA block copolymers by transformation of living cationic polymerization into ATRP methods.

Scheme 11.23 Synthesis of poly(2-ethyl-2-oxazoline)-b-polystyrene by transformation of CROP into ATRP methods.

Miktoarm stars of the type A2B2, where A is PS and B is PEO, were prepared by the combination of anionic and ATRP methods using the core-first procedure. Pentaerythritol was used as a... 

These structures are accessible by a variety of techniques that include atom transfer radical polymerization (ATRP) methods and the use of living cationic polymerization. Tri-arm star structures are accessible by the living cationic growth of three chains from a triamino core structure and dendrimers have been obtained by the growth of structures based on a diaminobutane polypropyleneimine core with polyphosphazene outer branches. ... 

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