Ring-opening Copolymerization of ε-Caprolactone and δ-Valerolactone Catalyzed by a 2,6-Bis(amino)phenol Zinc Complex

In combination with methyllithium, a 2,6-bis(amino)phenol zinc complex 1 was used in the ring-opening polymerization of δ-valerolactone in the absence or presence of benzyl alcohol and showed high efficiency, mainly producing cyclic and linear polyvalerolactones,respectively. On the basis of homopolymerization, the ring-opening copolymerization of ε-caprolactone and δ-valerolactone was investigated.The P(CL-co-VL) random copolymers, PCL-b-PVL and PVL-b-PCL diblock copolymers, were prepared by varying the feeding strategy(premixing or sequential feeding). The copolymer composition was adjusted by varying the feeding ratio of two monomers. The structure and thermal properties of obtained polymers were characterized by GPC, 1 H-NMR, 13 C-NMR, MALDI-TOF mass spectroscopy, and DSC, respectively.