Syndiotactic polymers structural data

A glance at the molecular structure of 11 shown in Fig. 18 reveals again that from a molecular symmetry point of view complex 11 (like complex 10) has all the structural and symmetry characteristics required to be classified as a syndiotactic-specific catalyst system after its activation. In practice, after activation with MAO, complex 11 does polymerize propylene to a high molecular weight s-PP very efficiently [29]. Tables 11 and 12 present the polymerization conditions, results and polymer analyses for 11/MAO and the syndiotactic polymers it produces. According to these data, only the syndiotacticity of the polymers produced at and below 40°C (measured as the concentration of racemic pentads rrrr about 75%) are... 

Taking into account the fact that the cyclopropyl radical is opened mainly by the conrotatory type [39] it should be expected that free-radical polymerization tends mainly to the syndiotactic type of stereoregularity. This conclusion does not seem to contradict reality [40,41]. As an illustration Table 1 gives the data [43-45] on the content of syndiotactic structures in three polymers. 

Thus, also in this case an increase in the quantity and quaUty of the available experimental data can help to remove ambiguity and aid to understand the polymer solidification in more detail. Interesting examples of the complex morphology that can be achieved in a transformation process come from the structural analysis of injection molded samples in Syndiotactic Polystyrene [22-25]. 

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