Synthesis of the thionolactone monomer. The 7-phenyloxepane-2-thione (POT, 9) was prepared in a two steps process (Figure ). A Baeyer-Villiger oxidation was first performed on phenylcyclohexanone to obtain the corresponding lactone using a published procedure (93 % yield). The second step is the thionation of the lactone using the Lawesson's reagent in anhydrous toluene that gives the POT monomer in 50 % yield as a brown oil that solidified upon cooling. The synthetic route is straightforward and allows to prepare easily POT in multigram scale. To compare with the synthesis of DOT and POT, we performed a preliminary economical study using the catalog price of the reactants from our local supplier. To do so, we considered the preparation of 2-phenylcyclohexanone from 2-chlorocyclohexanone as a first step and compared the POT three-step process to the two-step process to prepare DOT as reported by Johnson and coworkers. The price for preparing POT was estimated to be close to 50% lower than that of DOT. The detail of the calculation is given in ESI.