POLYLACTONES, 42 - ZN L-LACTATE-CATALYZED POLYMERIZATIONS OF 1,4-DIOXAN-2-ONE

1,4-Dioxan-2-one (DOXA) was polymerized by means of Zn L-lactate (ZnLa c(2)) as catalyst in bulk. Upon systematic variation of the temperatur e, the reaction time and the monomer/catalyst (M/C) mole ratio the hig hest molecular weights were obtained at 100 degrees C and M/C ratios b etween 2000 and 4000. However, long reaction times (8-14d) were requir ed to obtain optimum results. Zinc chloride proved to be a somewhat le ss reactive catalyst, whereas zinc bromide proved to be as efficient a s ZnLac(2). Addition of benzyl alcohol as a coinitiator at a fixed DOX A/ZnLac(2) ratio allowed a systematic control of the molecular weight. Furthermore the formation of benzyl ester endgroups was detected. Mor eover, ZnLac(2) allows the incorporation of various bioactive alcohols or phenols (e.g. testosterone, stigmasterol, ergocalciferol, cortison e, a-tocopherol) in the form of ester endgroups. Finally several prope rties of polydioxanone are reported and discussed, such as solubilitie s, IR, H-1 NMR and C-13 NMR spectroscopic data and thermogravimetric a nalysis.