In this study, a series of urea-derivatives of 4-aminopyridine (4AP) were evaluated as thermally latent initiators for the anionic ring-opening polymerization of diglycidyl ether of bisphenol A (DGEBA). The urea-derivatives were synthesized by the reactions of 4AP with the corresponding iso(thio)cyanates (phenyl isocyanate, tert-butyl isocyanate, methylene diphenyl diisocyanate, and phenyl isothiocyanate). The ability of the urea-derivatives as latent initiators was investigated with differential scanning calorimetry (DSC): Upon heating formulations comprised of DGEBA and the urea-derivatives in a heating rate at 10 degrees C/min, the resulting DSC profiles indicated exothermic peaks to confirm that DGEBA underwent the polymerization efficiently. The corresponding DSC-peak top temperatures (T-peaktop) was higher than that observed for the formulation comprised of DGEBA and pristine 4AP, to clarify that the urea are useful initiators with thermal latency. A possible mechanism for the initiation step involves the thermal dissociation of the urea into 4AP and the corresponding isocyanates. 4AP thus generated readily initiated the ring-opening polymerization of epoxide. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2518-2522