Fabrication and Mechanism Study of Cerium-Based P, N-Containing Complexes for Reducing Fire Hazards of Polycarbonate with Superior Thermostability and Toughness

A superior comprehensive performance is essential for the extensive utilization of polymers. Current flame-retardant strategies for polycarbonates (PCs) usually realize satisfied fire resistance at the cost of thermostability, toughness, and/or mechanical robustness. Thus, we report a rare-earth-based P, N-containing complex with a lamellar aggregated structure Ce(DPA)3 by a coordination reaction between a tailored ligand and cerium(III) nitrate. The results indicate that incorporating 3 wt % Ce(DPA)3 enables the resultant PC composite to achieve UL-94 V-0 rating, with a 55% reduction in the peak heat release rate. Besides, the initial (T5) and maximum (Tmax1 and Tmax2) decomposition temperatures are significantly increased by 21, 19, and 27 °C, respectively, in an air atmosphere. Moreover, the impact strength and elongation at break of the PC composite containing 3 wt % Ce(DPA)3 are greatly increased by 20 and 59%, respectively, relative to pristine PC, while its tensile strength (57 MPa) is still close to that of bulk PC (60 MPa). Notably, this work provides a novel methodology for revealing the evolution mechanisms of chemical structures of vapor and residual products during thermal decomposition, which is conducive to guiding fire and heat resistance modification of PC in the future.