The invention relates to a curable composition comprising prepolymer (A) having the formula: (L-C(.dbd.O)--O--).sub.nP wherein L is a group represented by the following formula ##STR00001## with the N,N' bridging unit being part of a heterocyclic quasi-aromatic ringsystem, optionally containing O, N or S, preferably an azolide, P is a prepolymer backbone having a molecular weight (Mn) of at least 500, n is at least 2, and crosslinker (B) comprising at least 3 nucleophilic groups. The curable composition can be used for coating, sealing, moulding, adhering, making impressions, especially in the dental field.