Synthesis of flame-retarding oligo(carbonate-ether) diols via double metal cyanide complex-catalyzed copolymerization of PO and CO2 using bisphenol A as a chain transfer agent

Abstract

Flame-retarding oligo(carbonate-ether) diols were successfully prepared with considerable efficiency by copolymerization of propylene oxide (PO) and carbon dioxide (CO₂) using a Zn₃[Co(CN)₆]₂-based double metal cyanide complex (DMC) in the presence of bisphenol A (BPA) as a chain transfer agent (CTA). The effects of molar ratio of PO to BPA, temperature, pressure and reaction time on the copolymerization were systematically investigated. The number average molecular weight (M_n) of the oligo(carbonate-ether) diols is in good linear relationship to the molar ratio of PO to BPA and can be facility tuned in the range of 1000–2400 g mol⁻¹ by adjusting reaction temperature and reaction time at fixed PO/BPA = 25.0. Lower temperature and higher CO₂ pressure were beneficial for incorporating CO₂ into the oligomer chain. The oligomer with a carbonate (CU) of 42% and M_n of 2400 g mol⁻¹ is obtained at 2.0 MPa CO₂ pressure and 75 °C with productivity of 2.4 kg g⁻¹ DMC within 6 h.