A series of novel poly(amide-imide) (PAI) films with different amide contents were prepared from pyromellitic dianhydride and four amide-containing diamines. These PAI films exhibited excellent mechanical and thermal properties with tensile strength of 203.7–297.4 MPa and T_g above 407 °C. The rigid backbone structures combined with strong intermolecular interactions provided PAI films with ultralow in-plane CTE values from −4.17 ppm/°C to −0.39 ppm/°C in the temperature range of 30–300 °C. The correlation between thermal expansion behavior and aggregation structures of PAI film was investigated. The results suggested that hydrogen bonding interactions could be maintained even at high temperature, thus resulting in good dimension reversibility of films in multiple heating-cooling cycles. It is demonstrated that dimensional stabilities of PAI films are determined by the rigidity, orientation, and packing of molecular chains. Heat-resistant PAI films with ultralow CTE can be developed as flexible substrates by regulating backbones and aggregation structures for optoelectronic application.

从均苯四甲酸二酐和四种含酰胺的二胺制备了一系列具有不同酰胺含量的新型聚（酰胺-酰亚胺）（PAI）薄膜。这些PAI膜表现出优异的机械和热性能，拉伸强度为203.7–297.4 MPa和T _g高于407°C。刚性骨架结构与强大的分子间相互作用相结合，为PAI膜提供了在30-300°C的温度范围内从-4.17 ppm /°C到-0.39 ppm /°C的超低面内CTE值。研究了PAI薄膜的热膨胀行为与聚集结构之间的相关性。结果表明，即使在高温下也可以保持氢键相互作用，从而在多个加热-冷却循环中导致膜的良好尺寸可逆性。结果表明，PAI膜的尺寸稳定性取决于分子链的刚性，取向和堆积。通过调节光电子应用的骨架和聚集结构，可以将具有超低CTE的耐热PAI膜开发为柔性基板。