Ring-opening (Co)Polymerization of Macrolactones Catalyzed by a Simple Organoaluminum Complex of MeAl(BHT)2

Abstract

Degradable aliphatic long-chain polyesters (ALCPEs), obtained from the ring-opening polymerization (ROP) of macrolactones (MLs), have emerged as a promising degraddable polymers, as they combine the mechanical and thermal properties of polyethylene with the degradability of polyesters. Herein, we report a highly efficient MeAl(BHT)2 catalyst for facile ROP of the bio-based macrolactone ω-pentadecalactone (PDL) and ω-dodecalactone (DDL). This system also enables the one-pot random copolymerization of MLs with ε-caprolactone (ε-CL) and δ-valerolactone (δ-VL), allowing for good control of the melting temperature (Tm) of the resulting copolyesters over a range of 48-95 °C by adjusting the monomer feed ratios. More importantly, well-defined block copolymers such as PDDL-b-PLLA, PDDL-b-PCL, and PDDL-b-PVL can be prepared using a sequential monomer addition strategy. The structures and compositions of these polymers were confirmed by nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry (DSC), and gel permeation chromatography (GPC).