Living alkene polymerization: New methods for the precision synthesis of polyolefins

Precise control over product structure is the goal of all chemical synthesis. In the field of polymer synthesis, the structure of the resultant macromolecule is intimately linked to its material properties, which ultimately determines the potential applications for the polymeric material. Method development for alkene polymerization is becoming increasingly focused on achieving fine control over all aspects of macromolecular architecture; especially chain composition, molecular weight, and stereochemistry. One of the most powerful methods developed so far which is capable of furnishing a high degree of control over polymer architecture is living alkene polymerization catalyzed by transition metal complexes. Living polymerization is characterized by efficient initiation and chain termination/transfer rates that are negligible in comparison to the rate of propagation. Using living alkene polymerization methods, polymer chemists have synthesized materials with microstructures that were inaccessible just a decade ago. Specific examples include polyolefin-based block copolymers, end-functionalized polyolefins, and stereo/regioblock copolymers with well-defined block structures. This review is a comprehensive account of living alkene polymerization systems with special attention paid to systems developed in the last 5 years. The text is organized by polymer type, which will allow those seeking to construct a specific polymer architecture to quickly identify relevant methodologies. (c) 2006 Elsevier Ltd. All rights reserved.