Flash‐Heating‐Enhanced Ring‐Opening Polymerizations of ε‐Caprolactone under Conventional Conditions

Summary: Flash conventional heating (FCH) and microwave heating (MH) were matched in their effects on the ROP of ε ‐CL catalyzed by Sn(Oct) 2 . The temperature of the ROP, heated by a hot salt bath, increased from room temperature to 215 °C within 3 min, which rose a little faster than that by MH (213 °C at 6 min), and the way of heating was considered as FCH. The kinetic results indicate that the chain propagation of PCL was significantly accelerated under FCH conditions and the ratio of the chain propagation rate constant by FCH to that by MH ( k / k ) was 4.48, if the concentrations of their propagating species were the same. The largest number‐average molar mass ( M ₙ ) of PCL obtained by FCH was 13.0 × 10 4 g · mol −1 at 6 min, but that by MH was 4.1 × 10 4 g · mol −1 at 15 min. The ratio of the concentrations of propagating species under the two conditions ([ Pₙ^* ]^ FCH /[ Pₙ^* ]^ MH ) was around one‐fifth at 4, 6, and 8 min. Thermal and kinetic behavior of the ROP of ε ‐CL. magnified image Thermal and kinetic behavior of the ROP of ε ‐CL.