Stereoregular Polymers

Abstract

Abstract Control of structure of polymers is an important issue in polymer synthesis because it affects the properties of polymers. In this article, general aspects of stereoregular polymers, especially of monosubstituted vinyl monomers, including definition, evaluation, and brief mechanism of the formation of stereoregular polymers are presented. The mechanism of stereoselective polymerization (chain‐end control and enantiomorphic site control) is also described. Recent progress in stereospecific polymerization of propylene, α‐olefins, and styrenes is also summarized. Metallocene catalysts of group 4 metals having C 2 , C s , or C 1 ‐symmetric structure are utilized for the stereospecific polymerization of propylene. Recently, a number of nonmetallocene complexes of Ti, Zr, Hf, Ni, and Fe were also found to be effective. Stereospecific polymerization of α‐olefins, such as 1‐hexene, is also achieved by the metallocene catalysts as well as nonmetallocene catalysts of Ti, Zr, Hf, and Sc. Half‐titanocene complexes and nonmetallocene titanium complexes, as well as rare earth catalysts, especially Sc, are utilized for the syndiospecific polymerization of styrene. Zirconocene complexes, lanthanocene complexes, and Ti complexes with OSSO ligands promote isospecific polymerization of styrene. Stereospecific living polymerization of those monomers as well as the synthesis of stereoblock copolymers is also mentioned.