Preparation of CO2-based poly(carbonate-co-lactide) with different porphyrin aluminum (III) catalysts

Two-component catalysts composed of tetra (para-X substituted) phenylporphyrin aluminum (III) chloride, T (p-X-P)PAlCl, (where X = H, F, Cl, Br, CH3, OCH3, tert-butyl), and cocatalyst bis(triphenylphosphine)imminium chloride (PPN+Cl-), could initiate the polymerization of propylene oxide (PO). And they could react with rac-lactide, (rac-LA), in the presence of propylene oxide (PO), to yield chains of enriched isotactic polylactide (PLA) with trace polyether segment. Also, these catalysts displayed different catalytic activity in the copolymerization of CO2 and PO, resulting in poly(carbonate-co-ether) copolymer with different carbonate unit content (CU%). Further, these catalysts could initiate one-pot regio- and stereo- selective terpolymerization of rac-LA, CO2 and rac-PO, resulting in multi-blocky poly(carbonate-co-lactide) with trace polyether segment. The structure of the products was verified by H-1 NMR, C-13 NMR, GPC, and DSC analysis, and it was found that variation of substitution groups in the periphery of porphyrin ligand would affect on the catalytic efficiency of ter-polymerization, and the relative polymerization reaction ratio of the ring-opening polymerization of LA (ROP) to the ring-opening copolymerization of PO and CO2 (ROCOP), resulting in ter-polymer with different contents of PLA segment and PPC segment. However, H-T% in polycarbonate unit and P-i% in polylactide unit did not vary much with the change of catalysts.