Effect of Monomer Feeding Strategy on the Sequence and Properties of Fluorine-Containing Polyarylates via Interfacial Polycondensation

Fluorine-containing polyarylates (F-PARs) were synthesized via interfacial polycondensation of hexafluorobisphenol A (BPAF), bisphenol A (BPA), and two acyl chloride monomers under four feeding strategies. Sequential feeding affords the highest <i>M</i>_w (2.02 × 10⁵ g/mol) and high alternating sequence content; the one-pot method gives intermediate <i>M</i>_w and a random sequence; and segmented and parallel methods yield lower-<i>M</i>_w polymers and pseudo-block sequences. Time-resolved GPC results reveal that the concentration of -CF₃-activated acyl chloride termini during chain propagation controls the subsequent chain propagation and, thus, the final <i>M</i>_w. Consequently, sequential feeding delivers the highest <i>T</i>_g (215 °C) and stiffness (2.51 GPa) for thermal-mechanical loads; the one-pot protocol maximizes optical clarity (<i>T</i>₄₅₀ = 85%) for transparent films. Systematic variation in the BPAF/BPA ratio via sequential feeding further reveals that higher BPAF content increases <i>M</i>_w, enhances thermal stability, and blue-shifts UV absorption, whereas BPA-rich compositions improve the tensile strength and modulus. These findings provide a quantitative roadmap for the rational design of F-PAR chain architectures, enabling on-demand tuning of thermal, mechanical, and optical properties without additional synthetic complexity.