ZN LACTATE AS INITIATOR OF DL-LACTIDE RING-OPENING POLYMERIZATION ANDCOMPARISON WITH SN OCTOATE

Zn lactate, 3H(2)O and dehydrated Zn lactate were used as initiator to polymerize DL-lactide under various conditions. It is shown that the latter does polymerize DL-lactide up to high molecular weight at a slo wer rate than Sn octoate. Zn lactate being formed when lactic acid is allowed to react with Zn metal, it is believed that the active species in Zn metal initiation is Zn lactate. Comparison was made of the two poly(DL-lactide) initiated with Zn metal and Sn octoate respectively a nd selected to have almost similar characteristics. It is shown that d egradation characteristics of the two polymers are different, especial ly water uptake and rate of heterogeneous degradation. It is further s hown that residual Sn concentrated within the matrix remnants whereas the content in Zn remained constant according to degradation controlle d release.