Simple sodium and potassium phenolates as catalysts for highly isoselective polymerization of rac-lactide

Abstract

A series of simple sodium and potassium phenolates can highly isoselectively catalyze the polymerization of rac-lactide (with a high P_m value of up to 0.89). Isotactic multi-block polymers were obtained with a longest average isotactic length of 9 (18 lactic acid units) and the highest melting point of the polymer reaching up to 187.8 °C. One highly active potassium complex can even catalyze the polymerization of 1000 equivalents of rac-lactide and afford polylactide with a desired molecular weight and narrow polydispersity index (PDI). Experimental results also demonstrate that steric hindrance and electronic effects have significant effects on the behaviors of these catalysts in the ROP of rac-lactide.