Resorbable initiators for polymerizations of lactones

Numerous salts were prepared from cations and anions belonging to the human metabolism, such as Na, K, Mg, Ca, Zn and Fe in combination with chloride, iodide, hydroxide, carbonate, acetate, stearate, glycolate, L-lactate, D-m andelate and various N-substituted alpha-amiono acids. All these salts were used as initiators for polymerizations of L-lactide in bulk at 100-180 deg rees C. Furthermore, Grignard reagents, hemin and hematin were included in this study. Zn L-lactate was found to be the most useful initiator in terms of reactivity, maximum molecular weight of the isolated poly(L-lactide) an d its optical purity, Zn L-lactate initiated copolymerizations of L-lactide and glycolide or epsilon-caprolactone were also studied.