Stereospecilic polymerization

Tani,H., Oguni,N. Stereospecilic polymerization of propylene oxide by N,N-bis(ethylzinc)-t-butylamine electron donor complex of catalyst and its implication for polymerization mechanism. J. Polymer Scl B7, 769 (1969). 

When the configurations at the centers are more or less random, the polymer is not stereoregular and is said to be atactic. Polymerizations which yield tactic polymers are called stereospecific. Some of the more important stereospecilic polymerizations of vinyl polymers are described briefly in Chapter 9. 

Twenty years later Reichert [9] and Breslow [10] discovered that the addition of small amounts of water to the alkylaluminum chloride co-catalysts resulted in a one to two orders of magnitude increase in ethylene polymerization activity. In the 1980s the first reports appeared concerning the homogeneous stereospecilic polymerisation, but they received relatively little attention because in the same period the first highly active, supported,... 

The structure of the dormant sites might be an irregular coordination of the monomer (Rg. 4.10b) or a change of the direction of the monomer coordination (Rg. 4.10c). Tlie polymerization reaction may be stopped after an irregular coordination of styrene. This also supports the chain-end controlled mechanism of stereospecilicity. 

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