Polyimide (PI), as an ideal interlayer dielectric material, is widely used in traditional communication fields. However, with the rapid development of 5G communication, conventional polyimide exhibits disadvantages such as signal delay and missing and is in urgent need of modification. Based on the β-relaxation theory, we designed and prepared three types of triphenylenediamine-containing monomers with different side group sizes (A-AmM, A-AmP, and A-AmBP) and polymerized them with benzene tetracarboxylic dianhydride (PMDA) to obtain three types of polyimides (MPI, PPI, BPPI), to investigate the effect of the relaxation behavior on the dielectric constant (D) of the polyimide. It was also polymerized with 4,4′-(hexafluoroisopropyl)diphthalic anhydride (6FDA) to three fluorinated Polyimides (MFPI, PFPI, BFPPI) to investigate the effect of polar groups on D and the dielectric loss (D). In addition, we also calculate the free volume of polyimide molecules under different side groups by materials studio simulation to further verify the effect of side groups on the D. The results show that, firstly, with the increase of side group volume, polyimide still maintains excellent thermal stability, and its dielectric constant gradually decreases and mechanical strength gradually increases. Secondly, the dielectric constant of FPIs is significantly lower than that of the PIs due to the low polar group, and the thermal and mechanical properties are almost unchanged. In addition, benefiting from the combined effects of β-relaxation and trifluoromethyl groups, BPFPI exhibits a low D (2.64@10 GHz) and D (0.0092@10 GHz), excellent thermal properties (glass transition temperature (T) = 282.3 °C, 5 % decomposition temperature (T) = 537 °C) and excellent mechanical properties (tensile modulus = 1.71 GPa, tensile strength = 134.7 MPa).

中文翻译：

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基于β-弛豫理论制备不同侧基大小的低介电常数三苯胺聚酰亚胺

聚酰亚胺（PI）作为一种理想的层间介质材料，广泛应用于传统通信领域。然而，随着5G通信的快速发展，传统聚酰亚胺呈现出信号延迟、丢失等缺点，亟待改性。基于β-弛豫理论，我们设计并制备了三种不同侧基大小的含三苯二胺单体（A-AmM、A-AmP和A-AmBP），并将其与苯四甲酸二酐（PMDA）聚合得到三种类型的聚酰亚胺（MPI、PPI、BPPI），研究弛豫行为对聚酰亚胺介电常数（D）的影响。它还与 4,4'-(六氟异丙基)二邻苯二甲酸酐 (6FDA) 聚合成三种氟化聚酰亚胺 (MFPI、PFPI、BFPPI)，以研究极性基团对 D 和介电损耗 (D) 的影响。此外，我们还通过Materials Studio模拟计算了不同侧基下聚酰亚胺分子的自由体积，以进一步验证侧基对D的影响。结果表明，首先，随着侧基体积的增加，聚酰亚胺仍然保持优良的热稳定性，其介电常数逐渐降低，机械强度逐渐增加。其次，由于低极性基团，FPI的介电常数明显低于PI，而热性能和机械性能几乎没有变化。此外，受益于β-弛豫和三氟甲基的共同作用，BPFPI表现出较低的D(2.64@10GHz)和D(0.0092@10GHz)、优异的热性能(玻璃化转变温度(T)=282.3℃) ，5%分解温度（T）= 537 °C）和优异的机械性能（拉伸模量= 1.71 GPa，拉伸强度= 134.7 MPa）。