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 (T-5) and maximum (T-max1 and T-max2) decomposition temperatures are significantly increased by 21, 19, and 27 degrees 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.

Automated summary

A rare-earth-based P, N-containing complex was synthesized and incorporated into polycarbonate composites, resulting in improved fire resistance, increased thermal decomposition temperatures, and enhanced impact strength and elongation at break. This study provides a novel methodology for understanding the chemical evolution mechanisms during thermal decomposition, which can guide future modifications for fire and heat resistance in polycarbonates.