A Terpolymerization Strategy for <scp> CO ₂ </scp> ‐Based Polycarbonate With Balanced Flame Retardancy, Thermal and Mechanical Performance

ABSTRACT To address the flammability issue of CO 2 ‐based polycarbonate (PPC), this study synthesized a phosphorus‐containing flame retardant via the addition reaction of maleic anhydride (MA) and lowly oxidized diphenyl phosphine oxide (DPO), and further prepared a high‐phosphorus‐content flame‐retardant functional CO 2 ‐based polycarbonate material (PPCO) by incorporating this monomer as the third component in ternary copolymerization of CO 2 and propylene oxide (PO). Performance testing revealed that the thermal properties of PPCO significantly improved with increasing content of the phosphorus‐containing monomer. Compared to PPC, its 5% weight‐loss degradation temperature ( T d,−5% ) and maximum weight‐loss degradation temperature ( T d,max ) increased by 96°C and 93°C, respectively, while the glass transition temperature ( T g ) reached 46°C. In terms of mechanical properties, the tensile strength of PPCO increased by 15.9 MPa and Young's modulus improved by 4.3‐fold relative to PPC. Most importantly, PPCO exhibited outstanding flame retardancy, achieving a limiting oxygen index (LOI) of 33.9% and meeting the UL‐94 V‐0 rating (no dripping). This research provides new insights for developing high‐performance flame‐retardant polycarbonate materials, and PPCO shows potential applications in flame‐retardant materials for building exteriors and the electronics industry.