Diphenyl Phosphate/4-Dimethylaminopyridine as an Efficient Binary Organocatalyst System for Controlled/Living Ring-Opening Polymerization of L-Lactide Leading to Diblock and End-Functionalized Poly(L-lactide)s

摘要

The ring-opening polymerizations (ROPs) of ε-caprolactone (ε-CL) and L-lactide (LLA) have been studied using the organocatalysts of diphenyl phosphate (DPP) and 4- dimethylaminopyridine (DMAP). The "dual activation" property of DPP and the "bifunctional activation" property of DPP/DMAP were confirmed by the NMR measurement for ε-CL and its chain-end model of poly(ε-caprolactone) and for LLA and its chain-end model of poly(L-lactide) (PLLA), respectively. The molar ratio of DPP/DMAP was optimized as 1/2 for the ROP of LLA leading to the well-defined PLLA, such as the molecular weight determined from ~1H NMR measurement of 19,200 g mol~(-1) and the narrow polydispersity of 1.10. Additionally, functional initiators were utilized for producing the end-functionalized PLLAs. The DPP-catalyzed ROPs of ε-CL and its analogue cyclic monomers and then the DPP/DMAP-catalyzed ROP of LLA produced block copolymers.