Equilibrium Polymerization Behavior of 1,4-Dioxan-2-one in Bulk

To clarify the equilibrium polymerization behavior of 1,4-dioxan-2-one, PDO, bulk polymerization was investigated with Sn(II) ethylhexanoate or triethylaluminum over a range of 60−180 °C. The thermodynamic parameters Δ H ls, Δ S ls, and ceiling temperature for the polymerization were −14.1 kJ mol -1, −26.1 J mol -1 K -1, and 265 °C, respectively. The parameters support the thermal instability of PPDO. The calculated thermal parameters of activation were E a = 71.8 kJ mol -1, Δ G p ⧧ = 106.2 kJ mol -1, Δ H p ⧧ = 68.5 kJ mol -1, and Δ S p ⧧ = −95.7 J mol -1 K -1 at 120 °C. These parameters of activation are nearly equal to those of l -lactide. PDO and PPDO are easily polymerizable and depolymerizable materials, respectively.