The paper reports the successful synthesis of microcapsules that incorporate thermally-reversible Diels-Alder or oxime-urethane bonds within the polymer of the microcapsule shell using an interfacial polymerisation technique. The mechanical strength of these microcapsules was found to be dependent on the structure of the thermally-reversible functionality, thus allowing for the design of strong microcapsules that demonstrated excellent stability in one-pot PU formulations. Release of the encapsulated isocyanate crosslinkers using a thermal stimulus demonstrated the potential of this technology for use in the controlled polymerisation of one-pot PU systems.