Semi‐alicyclic colorless and transparent polyimide (PI) films with intrinsically flame‐retardant features, excellent optical transparency, and good thermal stability have been designed and successfully prepared. For this target, an aromatic diamine with lateral diphenylphosphine oxide substituent, 2,5‐bis[(4‐aminophenoxy)phenyl]diphenylphosphine oxide (BADPO) was polymerized with two alicyclic dianhydrides, including hydrogenated pyromellitic dianhydride (HPMDA) and hydrogenated 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (HBPDA), respectively, via a one‐step high‐temperature polycondensation procedure to afford two PIs, PI‐a (HPMDA‐BADPO), and PI‐b (HBPDA‐BADPO). The derived PI films maintained the intrinsic good properties for semi‐alicyclic PI films, including excellent optical transparency in the ultraviolet–visible light region with the cutoff wavelength (λ_cut) around 322 nm and optical transmittance at the wavelength of 450 nm (T₄₅₀) higher than 83.0%. In addition, the PI films exhibited good thermal stability with the 5% weight loss temperatures (T_5%) higher than 460.0°C and glass transition temperatures (T_g) higher than 235.0°C. More importantly, the developed PI films exhibited intrinsic flame retardancy with the limited oxygen indices (LOI) of 41.1% for PI‐a and 28.8% for PI‐b. What is more, the PI films showed the flame retardancy class of UL94 VTM‐0 and low thermal energy and smoke release during combustion.

中文翻译：

---

基于脂环族二酐和芳香族含磷二胺的具有固有阻燃性的无色透明半脂环族聚酰亚胺薄膜：制备与性能

已经设计并成功制备了具有固有阻燃特性，优异的光学透明性和良好的热稳定性的半脂环族无色透明聚酰亚胺（PI）薄膜。对于该目标，将带有侧向二苯膦氧化物取代基的芳族二胺2,5-双[（4-氨基苯氧基）苯基]二苯膦氧化物（BADPO）与两个脂环族二酐聚合，包括氢化均苯四甲酸二酐（HPMDA）和氢化3,3 ``，4,4'-联苯四甲酸二酐（HBPDA），通过一步式高温缩聚程序分别得到两个PI，PI-a（HPMDA-BADPO）和PI-b（HBPDA-BADPO）。衍生的PI膜保持了半脂环族PI膜的固有良好性能，λ_切）322围绕纳米和光透射率在450nm（波长Ť ₄₅₀）大于83.0％高。此外，PI薄膜表现出与5％重量损失的温度（较好的热稳定性Ť _5％ ）比460.0更高℃，玻璃化转变温度（Ť_克）比235.0℃以上。更重要的是，已开发的PI膜表现出固有的阻燃性，PI-a的极限氧指数（LOI）为41.1％，PI-b的极限氧指数为28.8％。而且，PI薄膜的阻燃等级为UL94 VTM-0，燃烧过程中的热能和烟雾释放量低。