Controlled Ring-opening (Co)Polymerization of Renewable Macrolactones by Al-based Catalysts with Different Sidearms

It remains a challenging task to achieve ring-opening (co)polymerization (ROP) of macrolactones. Hence, we synthesized a series of Al -based catalysts and systemically investigated the effect of N-containing substituent on the sidearms on ROP of macrolactones. Al3 possessing N-methyl group could effectively achieve controlled ROP of pentadecalactone (PDL) and macro(di)lactone ethylene brassylate (EB) in combination with BnOH, furnishing polyethylene-like PPDL and PEB with M w up to 90.3 and 321 kg/mol, respectively. Random copolymerization of PDL and small-ring lactones ε -caprolactone ( ε -CL) and δ -valerolactone ( δ -VL) could prepare random copolyesters with tailored T m in the range of 57–94 °C by controlling the ratios of PDL and ε -CL, δ -VL. More importantly, well-defined block copolyesters could be obtained by sequential adding PDL and ε -CL, δ -VL, which have been proved by GPC-MALLS, DSC and 13 C-NMR.