Transition Metal Catalysts for Syndiotactic Polystyrene

NORIO TOMOTSU, THOMAS H. NEWMAN, MIZUTOMO TAKEUCHI, RICHARD CAMPBELL JR., and JORGEN SCHELLENBERG  

Polystyrene is an inexpensive and rigid plastic. Polystyrene is a kind of vinyl polymer. Structurally, it is a long hydrocarbon chain with a phenyl group attached to every other carbon atom. Usually, polystyrene is produced by a radical or anionic polymerization starting from the monomer styrene. These polymers are atactic and amorphous and consequently are not crystallizable. 

In the field of the transition metal catalyzed coordination polymerization, the stereoregularly controlled polymerization of vinyl monomers was dramatically improved by Sinn and Kaminsky [4]. They discovered the combination of a homogeneous metallocene and methylaluminoxane (MAO) acting as a 

Syndiotactic Polystyrene, Edited by Jurgen Schellenberg Copyright 2010 John Wiley Sons, Inc. 

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TRANSITION METAL CATALYSTS FOR SYNDIOTACTIC POLYSTYRENE TABLE 2.5 Effects of the Bite Angle of Cp Ligands on Catalyst Performance... 

For comprehensive reviews, see (a) Schellenberg, J., Tomotsu, N. Syndiotactic polystyrene catalysts and polymerization. Prog. Polym. Sci., 27,1925-1982 (2002). (b) Schellenberg, J. Recent transition metal catalysts for syndiotactic polystyrene. Progress Polym. Sci.,34, 688-718 (2009). 

Although there is dispute about the exact oxidation state of titanium in the active species [Ti(III) or Ti(IV)], it was suggested, from the results of ESR measurements, that Ti(III) species form highly active sites for producing syndiotactic polystyrene in styrene polymerisation systems with the TiBz4—[Al(Me)0]x catalyst [50]. The moderately low catalyst activity is attributable to the stability of the benzyl transition metal derivatives towards reduction. 

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