Supramolecular flame retardants enabled fire-extinguishing polycarbonate with enhanced thermal stability and reduced smoke release

The creation of mechanically robust, thermostable, and flame-retardant polycarbonate (PC) is highly desirable in the industry. Unfortunately, achieving such a comprehensive performance portfolio remains challenging due to their different governing mechanisms. Most flame retardants provide satisfactory fire retardancy at the expense of other properties. Herein, we rationally design three novel supramolecular flame retardants (PAPZ@Co, PAPZ@La, PAPZ@Fe) containing phosphorus, nitrogen, and transition metal elements based on ionic and metal-ligand coordination interactions. Benefiting from the it-it stacking and ionic interactions, these supramolecular flame retardants show high thermal stability and good compactivity with PC, thus maintaining the good tensile strength of the matrix. Particularly, PAPZ@Fe enhances the thermal stability of PC by improving the initial degradation temperature by 8 degrees C and char yields by 36.8 % at 800 degrees C. The addition of 1.5 wt% PAPZ@Fe enables PC to achieve a desirable UL-94 V0 rating and a high limiting oxygen index of 31.6 %, in combination with a 36.3 % decrease in the peak heat release rate. This work offers a facile strategy for creating highperformance PC for practical application in industry.