Cossee-Arlman mechanism

From Wikipedia, the free encyclopedia

 The introduction to this article provides insufficient context for those unfamiliar with the subject.
Please help improve the article with a good introductory style.

The Cossee-Arlman mechanism in polymer chemistry is thought to be the mechanism for the phenomenon of stereoregularity in ionic polymerisation of alkenes using Ziegler-Natta or metallocene catalysts.

The coordination sphere of the metal ligands sterically restricts the entry of olefins - this being enhanced by the use of internal donors (succinates, phthalates etc) & external donors (substituted silanes) (ref: www.answers.com/topic/coordination-polymerization)

Polymerization is thought to start with coordination of the olefin to the vacant site of an activated Ti-R species and subsequent insertion into the Ti-R bond (ref: dissertations.ub.rug)

[edit] References

  • Allegra G. (1971). "Discussion on the Mechanism of Polymerization of a- Olefins with Ziegler-Natta Catalysts". Die Makromolekulare Chemie 145 (3668): 235–246. doi:10.1002/macp.1971.021450119. 
  • Cossee, P. J. (1964). "Ziegler-Natta catalysis I. Mechanism of polymerization of α-olefins with Ziegler-Natta catalysts". J. Catal. 3 (1): 80–89. doi:10.1016/0021-9517(64)90095-8. 
  • Arlman, E. J. (1964). "Ziegler-Natta catalysis II. Surface structure of layer-lattice transition metal chlorides". J. Catal. 3 (1): 89–99. doi:10.1016/0021-9517(64)90096-X. 
  • Arlman, E. J.; Cossee, P. (1964). "Ziegler-Natta catalysis III. Stereospecific polymerization of propene with the catalyst system TiCl3---AlEt3". J. Catal. 3 (1): 99–104. doi:10.1016/0021-9517(64)90097-1.