Polyarylates Containing Both Fluorine and Bromine for Simultaneous High Heat Resistance, Enhanced Solubility, and Low Heat Release

ABSTRACT Halogenated polyarylates hold great promise for high‐performance films, yet current single‐halogen modification strategies often suffer from limited tunability. Herein, we reported a series of bromine‐fluorine copolyarylates synthesized via interfacial polymerization, leveraging the complementary steric and electronic features of Br and F. The incorporation of bulky CF 3 and Br substituents increases free volume and polarity, resulting in improved solubility in both weakly and strongly polar solvents. The glass transition temperature ( T g ) ranges from 211.93°C to 258.84°C, marking a notable enhancement of 8.8% to 32.9% compared to the commercial U‐100 polyarylate ( T g = 194.8°C) and underscoring exceptional thermal performance. Thermogravimetric analysis (TGA) demonstrates a positive correlation between the BPAF monomer content and the enhancement in both thermal stability and charring effect. Microscale combustion calorimetry (MCC) reveals all the prepared polymers exhibited very low flammability characteristics with heat release capacity (HRC) values as low as 23.40 J/g·K. Notably, the peak heat release rate (PHRR) decreases from 56.98 W/g (pure‐F system) and 53.59 W/g (pure‐Br system) to 27.96 W/g at a Br/F molar ratio of 1:1, corresponding to a 47%–51% reduction, which reveals a distinct synergistic effect. Mechanical properties remain competitive, with tensile strengths of 47.24–64.97 MPa and Young's moduli of 1432.15–2074.75 MPa. Overall, these results suggest a feasible molecular‐design approach for polyarylates that balanced heat resistance, reduced heat release, and improved solubility.