Abstract

To develop the colorless transparent fluorinated polyimide (PI) with low coefficient of thermal expansion (CTE) and high tensile strength, a series of ternary copolymerized fluorinated PIs were synthesized by 4,4-(Hexafluoroisopropylidene) diphthalic anhydride (6FDA), 2,2'-bis(trifluoromethyl) benzidine (TFMB), and the third monomer 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA). The physical properties of the PI films were effectively regulated and optimized by adjusting the ratio of the rigid BPDA and flexible 6FDA components. By increasing the BPDA content, the thermal stability, dimensional stability, and mechanical properties of the polymers were enhanced. Among them, the PI film which molar ratio of 6FDA and BPDA was 5 : 5 exhibited an excellent comprehensive performance with a λ₀ of 372 nm, T_max nearly 91%, the tensile strength beyond 108 MPa and possessed high glass-transition temperature T_g which was 315.8°С. Furthermore, the CTE of the PI film was calculated about 21 ppm/K in the range of 25–200°С, indicating great dimensional stability.

中文翻译：

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低热膨胀系数高拉伸强度的无色透明聚酰亚胺的合成与性能

摘要

为了开发具有低热膨胀系数（CTE）和高拉伸强度的无色透明氟化聚酰亚胺（PI），由4,4-（六氟异亚丙基）二邻苯二甲酸酐（6FDA）合成了一系列三元共聚氟化PIs，2,2 '-双（三氟甲基）联苯胺（TFMB）和第三单体3,3'，4,4'-联苯四甲酸二酐（BPDA）。通过调节刚性BPDA和柔性6FDA组分的比例，可以有效地调节和优化PI膜的物理性能。通过增加BPDA的含量，可以提高聚合物的热稳定性，尺寸稳定性和机械性能。其中，PI膜6FDA和BPDA的摩尔比为5：5表现出优异的综合性能与λ ₀的372纳米，T _max接近91％，抗拉强度超过108 MPa，玻璃化转变温度T _g为315.8°С。此外，在25–200°С范围内，PI膜的CTE计算值约为21 ppm / K，表明尺寸稳定性好。