Ring‐Opening Polymerization of L‐Lactide in Supercritical Chlorodifluoromethane

The ring‐opening polymerization of L ‐lactide initiated by 1‐dodecanol/stannous 2‐ethylhexanoate (DoOH/Sn(Oct) 2 ) was carried out in supercritical chlorodifluoromethane at various reaction times, pressures, and temperatures. The monomer conversion increased to ca 70 % on increasing the reaction time to 25 h. The molecular weight of the product also increased to ca 75,000 g/mol over the same period. Increasing the pressure resulted in an accelerated polymerization rate. The pressure‐induced increase in the rate of L ‐LA polymerization can be explained by the formation of chemical bonds in the transition state, which implies the production of a transition state with a lower partial molar volume than the reactants.