Anionic ring-opening polymerization of cyclic 1,3-dithiocarbonate and thermal depolymerization

A new anionic ring-opening polymerization (ROP) was used to synthesize polydithiocarbonates from cyclic dithiocarbonates. The polymerization was optimized in the presence of dibenzo-18-C-6 and NaH/EtOH, and carried out at 50 °C to suppress any retropolymerization. Six- and seven-membered cyclic dithiocarbonates underwent ROP to afford the corresponding polymers. Thermal depolymerization of the prepared polymers generated a dimer, which was found to be a back-biting mechanism according to 1H nuclear magnetic resonance (NMR) spectroscopy. The characteristic structure of the linear polymer was defined by 1H NMR and 13C NMR spectroscopy, and compared with the monomer. The ROP at 80 °C exhibited the formation of a polymer contaminated by a dimer. Thermal analysis of the polymers by differential scanning calorimetry and thermogravimetric analysis revealed a melting process at 85-110 °C and thermal instability accompanying a 5% weight loss at 150-230 °C.