We also confirmed the compatibility of the POT thionolactone with RAFT by preparing a library of block copolymers with thioesters units that could be inserted in one or both blocks. The degradation was very efficient and confirmed the interest of this technology to prepare block copolymers with one or two blocks that could be degraded. Homopolymerization of POT was also demonstrated. p(POT) could be obtained with full conversion and complete ring-opening mechanism. This work confirms our approach that uses the combination of theoretical and experimental experiments to identify rationally new structures or polymerization conditions for radical ring-opening polymerization. This approach is currently being used in our laboratory to extend the library of vinyl monomers that compatible with thionolactones.