Ring‐opening polymerization of 1,4‐oxathian‐2‐one and its copolymerization with δ‐valerolactone

Abstract Monomer 1,4‐oxathian‐2‐one ( OX ) was synthesized by a one pot two‐step method, and it was oxidized to the sulfone ester monomer, 1,4‐oxathian‐2‐one‐4,4‐dioxide ( OX‐SO 2 ). Three organic catalysts, 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD), 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU), and diphenyl phosphate (DPP) were screened for the ring‐opening polymerization (ROP) of OX in dichloromethane at 30°C. It was found that OX has a high polymerizability, the TBD‐catalyzed ROP is very fast but with serious side reactions, the DBU‐catalyzed ROP is moderately controlled, and the DPP‐catalyzed ROP is well controlled until the polymerization reach equilibrium. Bulk ROP of OX‐SO 2 was achieved with stannous octoate ((Sn[Oct] 2 ) at 130°C. Poly(OX) is a semicrystalline polyester ( T m = 40‐60°C, T g = −39.6°C), while Poly(OX‐SO 2 ) is a highly crystalline polyester( T g = 55°C, T m = 211°C with decomposition). Kinetics experiments of OX and δ‐valerolactone (VL) revealed that VL polymerized faster than OX with DPP as the catalyst. Thermodynamic parameters of the ROP of OX and VL under identical conditions were measured; the ROP of OX is thermodynamically more favorable than that of VL. A series of random copolymers of OX and VL was prepared using TBD as the catalyst and confirmed that the in‐chain heteroatom greatly affected the crystallization of the copolymers.