One‐pot regioselective and stereoselective terpolymerization of rac‐lactide, CO2 and rac‐propylene oxide with TPPMCl (M = Cr, Co, Al)/PPNCl binary catalyst

Abstract

AbstractTetraphenyl 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, CO2 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) (Pi ≥ 68.0%) and terpolymerization of CO2, 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 (Pi ≥ 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 1H NMR, 13C NMR, gel permeation chromatography, DSC and TGA. © 2018 Society of Chemical Industry