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With the rapid development of high-frequency communication and large-scale integrated circuits, insulating dielectric materials require a low dielectric constant and dielectric loss. Poly (aryl ether ketone) resins (PAEK) have garnered considerable attention as an intriguing class of engineering thermoplastics possessing excellent chemical and thermal properties. However, the high permittivity of PAEK becomes an obstacle to its application in the field of high-frequency communication and large-scale integrated circuits. Therefore, reducing the dielectric constant and dielectric loss of PAEK while maintaining its excellent performance is critical to expanding the PAEK applications mentioned above. This study synthesized a series of poly (aryl ether ketone) resins that are low dielectric, highly thermally resistant, and soluble, containing cyclohexyl and diphenyl fluorene. The effects of cyclohexyl contents on the properties of a PAEK resin were studied systematically. The results showed that weakly-polarized cyclohexyl could reduce the molecular polarization of PAEK, resulting in low permittivity and high transmittance. The permittivity of PAEK is 2.95–3.26@10GHz, and the transmittance is 65–85%. In addition, the resin has excellent solubility and can be dissolved in NMP, DMF, DMAc, and other solvents at room temperature. Furthermore, cyclohexyl provided PAEK with excellent thermal properties, including a glass transition temperature of 239–245 °C and a 5% thermogravimetric temperature, under a nitrogen atmosphere of 469–534 °C. This makes it a promising candidate for use in high-frequency communications and large-scale integrated circuits. [ABSTRACT FROM AUTHOR]

Hyperbranched polymers (HBPs) have the characteristics of low viscosity, high fluidity, and excellent solubility, which enable them to have many potential applications in various fields. In this study, unequal activity 3,4′,5-trifluoro dibenzophenone (B'B 2) monomers and large volume 9,9-bis (4-hydroxyphenyl) fluorene (A 2) monomers were used to prepare hyperbranched poly (aryl ether ketones) (HBPAEKs) through nucleophilic substitution reaction, and three different hyperbranched HBPAEKs with hydroxy-terminated, fluoro-terminated, and epoxy-terminated groups were synthesized. The properties of the three HBPAEKs were systematically characterized by FT-IR, NMR, GPC, TGA, DSC and others. The solubility test shows that the synthesized HBPAEKs were soluble in most common organic solvents. Thermal analysis results showed that the fluorine-terminated HBPAEKs had excellent thermal stability, with a 5% weight loss temperature of 568 °C (T d5% = 568 °C), which is equivalent to that of poly (ether ether ketone) (PEEK, T d5% = 573 °C). Moreover, by adding HBPAEKs, the Melt Flow Rates (MFR) of PEEK was increased by 59%, which can greatly improve the processability of PEEK. [Display omitted] • Three different terminated HBPAEKs were successfully synthesized with high branching degrees and excellent solubility. • The fluorine-terminated HBPAEKs showing excellent thermal stability, which is comparable to that of PEEK (T d5% =573 ℃). • The HBPAEKs significantly enhanced the MFR of PEEK, which effectively mitigated the poor processability of PEEK. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydroxyl-capped HBP resins containing 2,4,6-tris(p-phenyl)pyridine were synthesized. • The synthesis conditions of the HBP were optimized by orthogonal tests. • The effect of the addition of HBP on the properties of epoxy resins was investigated. • In addition to good properties [T g : 113.9 °C, impact strength: 57.03 kJ/m2]. Epoxy resins are well used in many fields, but their problem of poor toughness restricts the further expansion of their applications. Facing this problem, this study successfully prepared high toughness epoxy resins using hydroxyl-terminated hyperbranched poly(aryl ether ketone) (HBPAEK-OH) as a toughening agent. Firstly, HBPAEK-OH was synthesized based on molecular structure design, combined with the optimized conditions of heat resistance and solubility. Then HBPAEK-OH was mixed with bisphenol A diglycidyl ether (DGEBA) to prepare a series of epoxy resins (HBP/DGEBA-n) with superior thermal properties, whose glass transition temperature (T g) can reach 113.9 °C, which is about 38 °C higher than that of HBP/DGEBA-0. The tensile strength, flexural strength, impact strength, and elongation at break of HBP/DGEBA-n showed a tendency to increase and then decrease with the increase of HBPAEK-OH content, and the highest values reached 86.43 MPa, 128.50 MPa, 57.03 kJ/m2, and 7.15 %, respectively. Among them, the impact strength and elongation at break increased by 179.3 % and 87.2 %, indicating that the toughness of HBP/DGEBA-n was significantly improved. This study explores a new method for toughening epoxy resins, which improves their toughness and heat-resistant properties and provides new possibilities for their expansion in different applications. [ABSTRACT FROM AUTHOR]