Comparison study of ε‐caprolactone , L‐lactide , and ε‐decalactone polymerizations using aluminum complexes bearing pyrazole derivatives, and synthesis of polylactide‐ gradual ‐poly‐ε‐caprolactone copolymer

This study compared ε‐caprolactone (CL), L‐lactide (LA), and ε‐decalactone (DL) polymerizations, where aluminum complexes bridged by two pyrazole ligands was used as catalysts. The reactivites of these Al complexes between CL, LA, and DL polymerization were different that L Bu 2 Al 2 Me 4 , with the distort boat form, exhibits the greatest catalytic activity for LA and DL polymerization at 60°C but the lowest catalytic activity for CL polymerization at room temperature. This may be because dinuclear L Bu 2 Al 2 Me 4 cannot react with BnOH to form aluminum benzyl oxide at room temperature, making it unable to reduce catalytic activity. Because these aluminum complexes had different reactivities for LA and CL polymerizations, the selectivity of polylactide‐ gradual ‐poly‐ε‐caprolactones (PLA(10–80%)‐ gradual ‐PCL(59–79%)) (PLA‐ g ‐PCLs) was observed.