Scheme 1. Synthesis of ABA-type triblock polyesters (TBPEs). (A) (i) ROP [DL]0 = 1.7 M in toluene, 80 °C, catalyst = [LZnMg(C6F5)2] (see ESI† for chemical structure); (ii) ROCOP, 80 °C, excess CHO (1.5 equiv. relative to PA). (B) Conversion vs. time data for TBPE-4 (Table S1†) showing DL, PA or CHO conversion as a percentage of the total monomer conversion where [LZnMg(C6F5)2]0 : [BDM]0 : [PA]0 : [CHO]0 = 1 : 4 : 1000 : 700 : 1050 (Table S1†). (C) SEC traces for TBPE-4 (THF eluent) vs. narrow PS standards showing PDL (99% DL conv.) and purified polymer (99% PA conv.) after PE growth with RI and UV detectors.
