4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride) (BPADA) was reacted with three structurally different diamines to produce poly(amic acid)s, which were then imidized to produce colorless and transparent polyimide (CPI) films through stepwise thermal cyclization. The three amines used to synthesize CPI based on BPADA are: bis(3-aminophenyl)sulfone (APS), p-xylyenediamine (p-XDA), and bis[4-(3-aminophenoxy)-phenyl] sulfone (m-BAPS). The obtained CPI films were almost colorless and exhibited excellent optical transparencies. The solubility of the CPI films in various solvents was investigated, and all the CPI films were found to be soluble in common solvents such as chloroform, dichloromethane, N,N’-dimethyl acetamide, and pyridine. The thermo-optical properties and oxygen transmission rates (O₂TRs) of the CPI films were examined for various biaxial stretching ratios in the range of 100–150%, and their properties were compared. When the stretching ratio changed from 100 to 150%, the glass transition temperature and yellow index did not show any significant change; however, the O₂TR decreased for all CPI films.

中文翻译：

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等双轴拉伸无色透明聚酰亚胺，用于柔性显示基板

4,4'-（4,4'-异丙基二烯二苯氧基）双（邻苯二甲酸酐）（BPADA）与三种结构不同的二胺反应生​​成聚（酰胺酸），然后将其酰亚胺化以生成无色透明的聚酰亚胺（CPI）膜通过逐步热环化。用于基于BPADA合成CPI的三种胺为：双（3-氨基苯基）砜（APS），对二甲苯二胺（p -XDA）和双[4-（3-氨基苯氧基）-苯基]砜（m -BAPS ）。所得的CPI膜几乎是无色的，并且显示出优异的光学透明性。研究了CPI膜在各种溶剂中的溶解度，发现所有CPI膜都可溶于常见溶剂，例如氯仿，二氯甲烷，N，N'-二甲基乙酰胺和吡啶。检查了CPI薄膜在100-150％范围内的各种双轴拉伸比的热光学性能和氧气透过率（O ₂ TRs），并对其性能进行了比较。当拉伸比从100％变为150％时，玻璃化转变温度和黄度指数没有显示出任何明显的变化。但是，所有CPI胶片的O ₂ TR均下降。