Controlled ring-opening polymerization of omega-pentadecalactone with yttrium isopropoxide as an initiator

The ring-opening polymerization of omega-pentadecalactone (PDL), a 16-membe red lactone, in the bulk and in solution using yttrium isopropoxide as an i nitiator was investigated. All isopropoxide groups of yttrium isopropoxide participated in the initiation and the polymerization took place via acyl-o xygen cleavage of the monomer. The molecular weight of the resulting polyme rs could be controlled effectively by varying the monomer/initiator ratio. An induction period was observed for the bulk polymerization conducted at 6 0 degrees C. DSC analyses indicated that poly(omega-pentadecalactone) is a highly crystalline polymer, having a high crystallization rate.