:The ,stereochemical aspects of controlled polymerization of lactide and pbutyrolactone are discussed. The physicochemical and thermal properties of these polymers are shown to be depending on the stereochemical structure of the macromolecular chain. Different types of processes involving change of enantiomeric composition in the course of the polymerization reaction are examined in function of different initiators used. The formation of stereocomplexes from stereocopolymers of various enantiomeric compositions is reported.
SUMMARY: The polymerization of cyclohexene oxide (CHO) using yttrium isopropoxide and a bimetallic yttrium-aluminium isopropoxide initiation system is described. The reaction proceeds in bulk at room temperature leading to 70% yield in a few mins. High molecular weight polymers are obtained with a polydispersity index around 2. The polymerization in toluene solution is slower but leads to polymers with the same characteristics. Complete conversions can be obtained at low temperatures. NMR spectra of the resulting poly(cyclohexene oxide) revealed an atactic structure.
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