Shuo Wang,Pei Wang,Yunlong Sun,Jiyong Zhao,Zhipeng Wang
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 (Tg = 232–240 °C, Td5% = 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.
Bo-Wen Liu,Jia-Wei Long,Li Chen,Xiang-Xin Xiao,Xue-Bao Lin,Yu-Zhong Wang
Semi-aromatic polyamides (SaPAs) combining each advantages of aliphatic and aromatic polyamides received ever-increasing development in both academia and industrial circles. In this work, four kinds of SaPAs with fluorenyl pendent and different length of aliphatic spacers, named P–FPB, P–FPH, P–FPO and P–FPD respectively, were designed and synthesized via the aromatic nucleophilic substitution (S N Ar) polycondensation . The effects of both the rigid pendent and flexible methylene (4, 6, 8, 10) spacers on the comprehensive properties of the SaPAs were comprehensively investigated. At the presence of the rigid fluorenyl pendent and the intermolecular π–π stacking thereof, the resulting SaPAs exhibited enhanced glass transition temperature ( T g ), thermal stability, solubility in typical organic solvents and mechanical properties compared with the commercially available 6T based SaPa. Also with increasing the number of the methylene units of the SaPAs, their T g , Vicat softening temperature, tensile strength and modulus gradually decreased; while the initial decomposition temperature and impact strength anomalously increased. Rheological investigations and solubility tests further confirmed that the resulting SaPAs were suitable for processing either in melt or in solution. In addition, these polyamides displayed favorable dielectric properties for potential availability in electric and electronic applications.
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