One‐pot regioselective and stereoselective terpolymerization of rac ‐lactide, CO 2 and rac ‐propylene oxide with TPPMCl (M = Cr, Co, Al)/PPNCl binary catalyst

Tetraphenyl porphyrin metal compound (TPPMCl) (where the TPPMCl was TPPCrCl, TPPCoCl, TPPAlCl), in combination with cocatalyst PPNCl (bis(triphenylphosphine)iminium chloride, the molar ratio of TPPMCl to PPNCl was 1:0.5), was used to catalyze the polymerization of racemic lactide ( rac ‐LA) in racemic propylene oxide ( rac ‐PO) medium and the terpolymerization of rac ‐LA, CO 2 and rac ‐PO. It was found that these TPPMCl/PPNCl binary catalysts could initiate the stereoselective polymerization of rac ‐LA in rac ‐PO medium to form enriched isotactic polylactide (PLA) ( P i ≥ 68.0%) and terpolymerization of CO 2 , rac ‐LA, rac ‐PO to form PPC‐PLA‐PPO (PPC, poly(propylene carbonate); PPO, poly(propylene oxide)) multiblock copolymer. In particular the PPC‐PLA‐PPO multiblock copolymer thus formed displayed high regioregularity and stereoregularity, and has high head‐to‐tail structure content in the PPC block (H‐T% ≥ 63.6%) and high isotacticity in the PLA block ( P i ≥ 64.0%). The influence of catalyst formula, the monomer feeding ratio, reaction temperature, carbon dioxide pressure and reaction time on the terpolymerization was investigated by 1 H NMR, 13 C NMR, gel permeation chromatography, DSC and TGA. © 2018 Society of Chemical Industry