Anionic polymerization star-branch polymer synthesis

HIR Hirao, A., Inushima, R., Nakayama, T., Watanabe, T., Yoo, H.-S., Ishizone, T., Sugiyama, K., Kakuchi, T., Carlotti, S., and Deffieux, A., Precise synthesis of thermo-responsive and water-soluble star-branched polymers and star block copolymers by living anionic polymerization, Eur. Polym. J., 47, 713, 2011. 

Higashihara T, Hayashi M, Hirao A. Synthesis of weU-deflned star branched polymers by stepwise iterative methodology using Uving anionic polymerization. Prog Polym Sci. 2011 36 323-75. 

Hirao, A., Hayashi, M. and Haraguchi, N. (2000) Synthesis of well-defined functionalized polymers and star branched polymers by means of living anionic polymerization using specially designed 1,1-diphenylethylene derivatives. Macromol. Rapid Commun., 21,1171-1184. 

The advantage of this procedure is that, in essence, any monomer that undergoes living anionic polymerization from a DPE anion can be used. On the other hand, the successive synthesis of star-branched polymers can no longer be continued. 

Hayashi, M., Kojima, K., and Hirao, A. (1999a) Synthesis of star-branched polymers by means of anionic living polymerization coupled with functional group transformation. Macromolecules, 32,2425-2433. 

Higashihara, T. and Hirao, A. (2004) Synthesis of asymmetric star-branched polymers consisting of three or four different segments in composition by means of Uving anionic polymerization with a new dual-functionaUzed 1,1-bis (3-chloromethylphenyl)ethylene. Journal of Polymer Science Part A-Polymer Chemistry, 42,4535-4547. 

Hirao, A. and Higashihara, T. (2002b) Synthesis ofbranched polymers by means of living anionic polymerization. 13. Synthesis of well-defined star-branched polymers via an iterative approach using living anionic polymers. Macromolecules, 35,7238-7245. 

Hirao, A., Inoue, K., and Higashihara, T. (2006a) Successive synthesis of regular and asymmetric star-branched polymers by iterative methodology based on Uving anionic polymerization using functionalized 1,1-diphenylethylene derivatives. Macromolecular Symposia, 240,31-40. 

Hirao, A., Sugiyama, K., Tsunoda, Y. et al. (2(X)6) Precise synthesis of well-defined dendrimer-Uke star-branched polymers by iterative methodology based on living anionic polymerization. Journal of Polymer Science Part A-Polymer Chemistry, 44,6659-6687. 

Zhao, Y, Higashihara, T., Sugiyama, K., and Hirao, A. (2007) Synthesis of asymmetric star-branched polymers having two polyacetylene arms by means of living anionic polymerization using 1,1-diphenylethylene derivatives. Macromolecules, 40,228—238. 

In the following sections, the general methods for synthesis of regular star-branched polymers and heteroarm star-branched polymers will be described. Specific examples will be shown based on alkyllithium-initiated anionic polymerization. 

The synthesis of well-defined LCB polymers have progressed considerably beyond the original star polymers prepared by anionic polymerization between 1970 and 1980. Characterization of these new polymers has often been limited to NMR and SEC analysis. The physical properties of these polymers in dilute solution and in the bulk merit attention, especially in the case of completely new architectures such as the dendritic polymers. Many other branched polymers have been prepared, e.g. rigid polymers like nylon [123], polyimide [124] poly(aspartite) [125] and branched poly(thiophene) [126], There seems to be ample room for further development via the use of dendrimers and hyperbran-... 

Anionic polymerization of functionalized cyclotrisiloxanes is a good method for the synthesis of well-defined functionalized polysiloxane with control of molecular mass, polydispersion, and density and arrangement of functional groups. These polymers may serve as reactive blocks for the building of macromolecular architectures, such as all-siloxane and organic-siloxane block and graft copolymers, star-, comb- and dendritic-branched copolymers and various polysiloxane-inorganic solid hybrids. 

Star polymers are branched polymers consisting of several linear chains linked to a central core. The synthesis of star polymers has been the subject of numerous studies since the discovery of living anionic polymerization.7-10... 

Anionic polymerization has proven to be a very powerful tool for the synthesis of well-defined macromolecules with complex architectures. Although, until now, only a relatively limited number of such structures with two or thee different components (star block, miktoarm star, graft, a,to-branched, cyclic, hyperbranched, etc. (co)polymers) have been synthesized, the potential of anionic polymerization is unlimited. Fantasy, nature, and other disciplines (i.e., polymer physics, materials science, molecular biology) will direct polymer chemists to novel structures, which will help polymer science to achieve its ultimate goal to design and synthesize polymeric materials with predetermined properties. 

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