Among the increasing wealth of degradable polymers, polythioesters are gaining interest because of enhanced mechanical properties compared to their (oxo)ester counterparts, and as degradable, sustainable materials, including for emerging biomedical applications. Polythioesters are typically prepared through anionic/catalytic ring-opening polymerization (ROP) of thiolactones (featuring cyclic -C(=O)S-). Recently, the ROP of unstrained thionolactones (cyclic -C(=S)O-) was shown to give polythioesters through S/O isomerization. Only few reports have described the synthesis of polythioesters through the cationic ring-opening polymerization (CROP) of thionolactones (which likewise involves S/O isomerization). In 2000, Endo's group observed quantitative conversions of the 7-membered monomer ε-thionocaprolactone when initiated with BF3•Et2O. The lanthanide triflate-initiated CROP of the 5membered homologue γ-thionobutyrolactone reported in 2005 by the same group, on the other hand, gave lower conversions (53-78%) and low SEC-measured molar masses (3.4-6.3 kg/mol). A screening of different cationic initiators for the same cyclic monomer and substituted derivatives by Xia et al. in 2023 showed [Et3O] + [B(C6F5)4] -to be the ideal candidate to achieve efficient polymerization and a high degree of polymer crystallinity. During the writing of this manuscript, Peng et al. reported the BF3•Et2O-initiated CROP of the dibenzo-substituted εthionocaprolactone dibenzo[c,e]-oxepine-5(7H)-thione (DOT). Notably, all these polymerizations were done under inert atmosphere, typically in a glovebox. In 2019, a radical approach to polythioesters was reported independently by Gutekunst and our group. DOT was shown to undergo radical ring-opening copolymerization with a variety of vinyl monomers including acrylates, acrylamides, styrene, , and maleimides. DOT-containing copolymers have since been shown to be promising for degradable latexes, networks, and adhesives, recycling of polymers, and drug delivery. However, DOT does not homopolymerize well radically, meaning that the degradation of DOT-containing copolymers into predetermined small molecules is limited to rare cases of alternating copolymerization. Polythioester homopolymers made through anionic/catalytic ROP are known to degrade in the presence of base through the backbiting of a terminal thiol (the reactive chain end) which produces a cyclic thiolactone monomer. As this depolymerization can occur under polymerization conditions, strategies such as introduction of substituents or fused rings have been used to increase the ring strain and drive the equilibrium toward the polythioester product. Capping the terminal thiol as a thioester or thioether was shown to prevent base-mediated depolymerization. There has recently been renewed interest in depolymerization in the context of the chemical recycling of polymers with the nature of the end groups playing a pivotal role. For example, in the radical polymerization arena, Anastasaki's group demonstrated the importance of the ω-end group on the depolymerization efficiency of vinyl polymers with more labile or reactive end groups facilitating an efficient end-to-end unzipping. To the best of our knowledge, the influence of ω-end groups on the depolymerization of cationically-made polythioesters has not been investigated. Notably, the CROP of thionolactones does not proceed via thiol(ate) end groups, but cations which are quenched during workup which provides an end-cap.