Fluorine-ContainingPolyether Ketones Based on FluoreneSide Groups with Low Dielectric Constants and Excellent Thermal Performance

The rapid advancement of high-frequency communication networks has imposed more rigorous demands on the overall characteristics of dielectric materials. Poly­(aryl ether ketone)­s (PAEKs) are good candidate materials for applications in microelectronic devices due to their excellent thermal stability, mechanical properties, and chemical stability. In this work, we endeavored to incorporate large-volume fluorene structures into fluoro-PAEKs, employing strategies to enhance the polymer free volume and reduce polarizations in order to decrease the values of Dk and Df at high frequency. Therefore, a series of poly­(ether ketone) (PEK-pOCFBPF-X) copolymers were designed and synthesized through nucleophilic polymerization using 4,4-difluorobenzophenone (DFK), phenolphthalein anilide-containing trifluoromethoxy groups (PPPBP-pOCF₃), and a structurally ordered bisphenol fluorene (BPF) as the monomers. The results demonstrate that the introduction of BPF into fluoro-PAEKs resin leads to a low dielectric constant (2.713–2.782@10 GHz) and dielectric loss (0.00597–0.00825@10 GHz), as well as exceptional thermal properties (<i>T</i>_g = 232–240 °C, <i>T</i>_{d5% =} 518–536 °C). Moreover, the copolymer exhibits high mechanical strength (tensile strength ≥ 81 MPa), minimal water absorption (≤0.0063), and excellent solubility. The incorporation of trifluoromethoxy and fluorenyl groups into copolymers significantly enhances the free volume fraction (5.5%–5.8%), resulting in a lower density and reduction in the dielectric constant. Simultaneously, by introducing C–F bonds with lower polarizability, the overall polarizability of the polymer is effectively diminished. These fluoro-PAEKs films, which exhibit superior thermal stability and a low dielectric constant, have great potential for applications in the high-performance flexible electronic packaging field and communication usage.