无色透明耐高温聚酰亚胺薄膜的制备与性能研究

Preparation and characterization of colorless high temperature resistant polyimide films

分别采用两种联苯型二酐单体,对称结构的3,3’,4,4’-联苯四甲酸二酐(s-BPDA)以及不对称结构的2,3,3’,4’-联苯四甲酸二酐(a-BPDA)与含氟芳香族二胺1,4-双(4’-氨基-2’-三氟甲基苯氧基)联苯(TFDAB)通过两步缩聚法制备了两种聚酰亚胺材料PI-1(s-BPDA/TFDAB)与PI-2(a-BPDA/TFDAB)。研究结果表明,不对称结构可以显著增加PI薄膜在可见光区的透明性。25μm厚的PI-2薄膜在450nm处的透光率达到93%,而同样厚度的PI-1薄膜的透光率只有67%。此外,在PI分子结构中引入不对称结构不会牺牲材料的耐热稳定性、力学性能与介电性能。

Two dianhydrides, 3, 3＇, 4, 4＇-biphenyltetracarboxylic dianhydride （s-BPDA） or 2, 3, 3＇, 4＇-biphenyltetracarboxylic dianhydride （a-BPDA） were used to react with a fluoro-containing diamine, 1, 4-bis（4＇-amino-2＇-trifluoromethylphenoxy） biphenyl （TFDAB） via two-step polymerization procedure to yield two novel polyimides PI-1（s-BPDA/TFDAB） and PI-2 （a-BPDA/TFDAB）. It was shown that asymmetric structure endowed the polyimide film good transparency in the visible light region. For example, PI-2, derived from asymmetric dianhydride a-BPDA and TFDAB, exhibited more than 93% of transmittance at 450nm wavelength. Furthermore, asymmetric structure didn＇t deteriorate the thermal stability and mechanical properties of the polyimides.