To perform and monitor easily the copolymerization, we used anisole as a solvent (30 mol%) and followed the polymerization by 1 H NMR spectroscopy. In this preliminary study, only 5 mol% of POT were used as an additive to impart degradability without changing the properties of the polymer. After 90 min, in both cases, we observed a color change from brown to pale yellow suggesting the isomerization of the C=S bond from thionoester to thioester occurring via the β-fragmentation process. The conversion determined by 1 H NMR for styrene and POT reached 40 and 50 %, respectively, whereas the conversion of acrylate and POT reached 86 and 100%, respectively. The obtained copolymers are in the same range of molar masses, close to 15,000 g.mol . This result is very promising since we could expect a random incorporation of the monomer into the copolymer backbone and thus a rather good degradation profile. The 1 H NMR spectra before and after polymerization are depicted in Figure with the structure of the polymer obtained after the radical ring-opening copolymerization of POT with the vinyl comonomer (styrene or methyl acrylate). It is worth noting that there is no signal originating from ring-retaining polymerization (no C signal between 60-100 ppm). The degradation of these two preliminary copolymers was then studied using accelerated conditions.