Synthesis of poly(2-furyloxirane) with high molecular weight and improved regioregularity using macrocyclic ether as a cocatalyst to potassium tert-butoxide

2-Furyloxirane (FO), a monomer usually obtained from a nonpetroleum route, was prepared from the epoxidation reaction of furfural and trimethylsulfonium chloride. About 200-300 g FO can be obtained in each preparation process. Although anionic polymerization of FO generally gives low- molecular-weight polymers even after long periods of polymerization, the reaction was greatly improved when macrocyclic ether was used as a cocatalyst to potassium tert-butoxide. When 18-crown-6 was used as a cocatalyst, poly(2-furyloxirane) (PFO) with a number-average molecular weight (Mn) of 41.5 kg/mol and a polydispersity index of 1.3 was obtained at 94% yield after polymerization at 40 °C for 72 h. The PFO obtained contained a 61.7% head-to-tail (H-T) structure in the absence of the macrocyclic ether, and it reached 70.6% when cryptand[2,2,2] was used as a cocatalyst. PFO with higher regioregular structures showed improved thermal properties. For PFO with Mn of around 20.0 kg/mol, its glass transition temperature (Tg) increased from −3 to 6 °C when the H-T content was increased from 61.7 to 70.6%. Raising the Mn of PFO also raised Tg. For PFO with 68.9% H-T structure, its Tg could reach 7 °C when Mn was increased to 40 kg/mol. This study shows two effective ways to improve the thermal and mechanical performances of the polymer.