Olefins, living polymerization

Additionally, research on FI catalysts has provided useful information on high catalytic activity, the formation of highly syndiotactic PPs with C2-symmetric catalysts, the origin of highly controlled living olefin polymerization, and the high incorporation capability for higher a-olefins. 

The production of olefin block copolymers has been an aspiration of academic researchers and polymer manufacturers alike. Tremendous progress toward this end has been achieved in recent years with the discovery of several designer catalysts capable of living olefin polymerization. However, the stoichiometric nature of the living process, coupled with related process limitations of low polymerization temperatures and slow batch processes, have precluded these approaches from widespread application. 

Living olefin polymerization allows the synthesis of end-functionalized polyolefins if appropriate initiation and/or quenching methods are used. Doi et al. first showed the utility of living olefin-polymerization catalysts for the preparation of end-functionalized polyolefins. They synthesized iodine-, amine-, aldehyde-, hydroxy-, and metha-cryl-terminated PPs using living V-PP species and appropriate reagents. " " ... 

In early 1981 Sinn and Kaminsky reported that mixtures of bis-cyclopentadienyl-zirconiumdimethyl (Cp2ZrMe2, a metallocene ) and methylalumoxane (MAO a complex and ill-defined mixture of oxo-bridged alkylaluminum oligomers produced by the partial hydrolysis of trimethylaluminum) produced a highly active and long-lived olefin polymerization catalyst [18]. The unique properties of this... 

Tian, J., Hustad, P.D., Coates, G.W., 2001. A new catalyst for highly syndiospecific living olefin polymerization homopolymers and block copolymers from ethylene and propylene. J. Am. Chem. Soc. 123 (21), 5134-5135. 

While most Ziegler catalysts involve chain termination and chain transfer, only a few catalyst systems have been reported to afford living propylene pol5unerization where all polyolefin chains contain active transition metal alkyl end groups. A characteristic feature of living olefin polymerization is the increase of degree of polymerization proportional... 

Living Poiymerization. Polymerization in the absence of both chain transfer and termination, or living pol5unerization, has value to the study of metallocene reactivity, but little potential beyond very specialized applications. If initiation of polymerization is rapid on the timescale of the polymerization run, PDIs will approach 1.0, the limiting value representing monodispersity. Several examples of metallocene-based living olefin polymerization catalysts have appeared in the literature (105,163). 

Mitani, M. Nakano, T. Fujita, T. Unprecedented living olefin polymerization derived Irom an attractive interaction between a ligand and a growing polymer chain. Chem. Eur. J. 2003,9,2396-2403. 

Hexene is one of the most commonly employed monomers for detailed studies of living olefin polymerization due to the fact that it is an easily handled liquid, and molecular-weight... 

Beyond block copolymer synthesis, one of the important applications of living olefin polymerization is in the synthesis of end-functionalized polymers, which is typically achieved by reaction of the living chain end with an electrophile. The vanadium-based living olefin polymerization catalysts discovered by Doi and coworkers proved to be particularly amenable to this application (Doi et al, 1983 Doi et ai, 1984 Doi and Keii, 1986 Doi et al, 1987a Ueki et al, 1995). In addition to end-functionalized polymers, one challenging goal in polymer... 

Figure 9.4 Titanium, zirconium and hafnium complexes for living olefin polymerization.

Figure 9.9 Nickel and palladium a-diimine catalyst for living olefin polymerization.

The last decade has seen significant new advances achieved in the field of living olefin polymerization. Many efficient and selective catalysts are now available for the hving polymerization of ethylene in addition to living and stereoselective polymerization of a-olefins, resulting in the creation of a variety of new polymer architectures, such as block copolymers and end-functionalized macromolecules. The ability to synthesize such polymers... 

Hong, S.C., Jia, S., Teodorescu, M. et al. (2002) Polyolefin graft copolymers via living polymerization techniques Preparation of poly(n-butyl acrylate)-gra/t-polyethylene through the combination of Pd-mediated living olefin polymerization and atom transfer radical polymerization. Journal of Polymer Science, Part A Polymer Chemistry, 40,2736-2749. 

Ruokolainen, J., Mezzenga, R., Fredrickson, G.H. et al. (2005) Morphology and thermodynamic behavior of syndiotactic polypropylene-poly(ethylene-co-propylene) block polymers prepared by living olefin polymerization. Macromolecules, 38,851-860. 

Sakuma, A., Weiser, M.S., and Fujita, T. (2007) Living olefin polymerization and block copolymer fimnation with FI catalysts. Polymer Journal, 39,193-207. 

Weiser, M.S., Wesolek, M., and Mulhaupt, R. (2006b) The synthesis and X-ray structure of a phenoxyimine catalyst tailored for living olefin polymerization and the synthesis of ultra-high molecular weight polyethylene and atactic polypropylene. Journal of Organometallic Chemistry, 691,2945-2952. 

Stdieme 1 Synthesis of a physical blend and a block copolymer using conventional coordination polymerization and living olefin polymerization catalyst systems. From Hustad, P. D. Sc/ence 2009,325,704. Reprinted with permission from AAAS. 

---