Zn–Cr double metal cyanide catalysts synthesized by ball milling for the copolymerization of CO2/propylene oxide, phthalic anhydride/propylene oxide, and CO2/propylene oxide/phthalic anhydride

• Efficient synthesis of Zn–Cr DMC catalyst via ball milling.
• Zn–Cr DMC was effective for both copolymerization and terpolymerization
• Polymer PPC, PPA, and PPCPA obtained under controlled reaction conditions
• All the polymers have high Mn, narrow PDI and high selectivity.

A highly active double metal cyanide complex (DMC) catalyst based on Zn–Cr was successfully synthesized by ball milling, an environmentally-friendly and efficient synthetic technique. The Zn–Cr DMC showed not only high catalytic activity for the alternating copolymerization of CO2 with propylene oxide (4 MPa, 70 °C, 24 h) and phthalic anhydride with propylene oxide (110 °C, 5 h), but also effectiveness for the terpolymerization of CO2, propylene oxide and phthalic anhydride (4 MPa, 70 °C, 24 h) under controlled conditions. The Zn–Cr DMC showed relatively modest activity and yielded polymers with high molecular weight (Mn PPC: 68.6 K, PPA: 4.1 K, PPCPA: 15.9 K) and narrow polydispersity index (PDI PPC: 1.68, PPA: 1.29, PPCPA: 1.09). FT-IR, 1H NMR and 13C NMR confirmed product formation.

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