Stereospecific Polymerization of Styrene with Ziegler-Natta-Catalysts

Example 3.30 Stereospecific Polymerization of Styrene with Ziegler-Natta-Catalysts 

Safety precautions Before this experiment is carried out. Sect. 2.2.5 must be read as well as the material safety data sheets (MSDS) for all chemicals and products used. 

Caution Alkylaluminum reagents must be handled under total exclusion of atmospheric oxygen and moisture (see Example 3.28). 

For the separation of the amorphous portion the dried polymer is stirred for 3 h in 500 ml of acetone, to which 2 ml of concentrated hydrochloric acid has been added. The insoluble portion is filtered off and dried in vacuum at 60°C. Yield 85-95% of crystallizable polystyrene. 

The crystallization of the acetone-insoluble polystyrene is completed by boiling for 2 h in freshly distilled butanone it is then allowed to stand overnight at room temperature and finally filtered and dried in vacuum at 60°C. Yield of crystalline isotactic polystyrene 95-100% of the acetone insoluble portion. The crystalline melting range and the density (see Sect. 2.3.5.1) are determined, as is also the limiting viscosity number in toluene at 20°C. 

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