Large-scale microwave-assisted ring-opening polymerization of ɛ-caprolactone

To probe into the industrialization possibility of microwave-assisted ring-opening polymerization (ROP) of ɛ-caprolactone (ɛ-CL), it was performed with monomer mass from 750 to 2450 g using a self-designed industrial microwave oven (6000 W) catalyzed by stannous octanoate (Sn(Oct)2) (M/Cat = 1000). The large-scale ROP of ɛ-CL proceeded smoothly at various microwave power levels (850, 1700, and 2550 W) and produced poly(ɛ-caprolactone) (PCL) with weight-average molar mass (Mw) from 66,000 to 12,2000 g/mol within 40 min in a yield over 93%. The structure of PCL was characterized by 1H and 13C NMR, FT-IR, DSC and WAXD. We propose that the microwave ROP of ɛ-CL is a potential technology to prepare PCL commercially.