Process for organocatalytic ring-opening polymerization

A process for organocatalytic ring-opening polymerization of at least one monomer M suitable for ring-opening polymerization selected from the group comprising alkylene oxides selected from the group consisting of ethylene oxide, propylene oxide and butylene oxide, and cyclic lactones, lactides, cyclic siloxanes, or of mixtures thereof, wherein, in a step (i), at least one N-heterocyclic compound of the formula (I)

• where A is selected from the group consisting of N, O and S, preferably N—where no R2 radical is present when A is O or S—and where R1 and R2 are each independently selected from alkyl and aryl, and where R3, R4 and R5 are each independently selected from H, alkyl, aryl, and where ring closures between R1 and R3, R3 and R4, and R4 and R2 are also possible, is subjected in the presence of at least one Zerevitinov-active compound Z1 to a temperature of at least 80° C., preferably at least 100° C., for a period of at least 30 seconds, preferably at least 5 minutes, and, in a step (ii), the monomer M is added and reacted, preferably in the presence of a Zerevitinov-active compound Z2.