Propylene oxide stereosequence distribution

The stereoregularity—i.e., distribution of the stereosequence length in these polymers—has a marked effect on the crystallization rates and the morphology of the crystalline aggregates. These differences, in turn, influence the dynamic mechanical properties and the temperature dependence of the dynamic mechanical properties. In order to interpret any differences in the dynamic mechanical properties of polymers and copolymers of propylene oxide made with different catalysts, it was interesting to study the differences in the stereosequence length in the propylene oxide polymers made with a few representative catalysts. 

Propylene Oxide Polymers of Varying Stereosequence Distribution... 

A number of catalyst systems have been developed (2 fL>A which result In propylene oxide polymers of different stereosequence distribution. In the following, we review some of our work on the characterization of stereosequence length In propylene oxide polymers prepared with different catalysts, and more importantly, studies on the effect of the differences in stereose-sequence length on the crystallization behavior and mechanical properties of the polymers. 

The effect of stereosequence distribution on crystallization kinetics Is dramatic. We have previously reported our studies on the Important effects of stereosequence length on crystallization kinetics and morphology of propylene oxide polymers (22). Here we summarize the main conclusions of this study, so that results on the time-temperature dependence of mechanical response may be fully appreciated In the light of these conclusions. 

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