Thermally responsive shape memory polyimides (PIs) have attracted significant attention in the high-tech fields like aerospace industry. At the same time creating of materials and approaches to the formation of three-dimensional (3D) shape memory structures containing PIs remains an urgent task. In this work we have developed new photopolymeric compositions (PPCs) based on high-performance readily soluble PI, reactive solvent (N,N-dimethylacrylamide) and photoactive cross-linker (bisphenol A ethoxylate diacrylate (BAEDA) or [2-(acryloyloxy)ethyl] isocyanurate (TAI)). The resulting PPCs were used to form 3D-structures using LCD 3D-printing. It has been found that the nature of the cross-linker and post-processing temperature have a significant impact on the thermal and mechanical properties of the materials. The tensile strength has the maximum value after the thermal post-curing at 250°С for 1 h (83.3 ± 7.4 MPa and 60.8 ± 4.8 MPa for PPCs with TAI and BAEDA, respectively). Moreover, 4D-printed PI-containing materials exhibit an excellent shape memory performance at recovery temperatures >150 °C, with shape fixity ratio >99% and shape recovery ratio up to 95.6%.

中文翻译：

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基于聚酰亚胺、N,N-二甲基丙烯酰胺和光敏交联剂的高温形状记忆聚合物的 4D 打印

热响应形状记忆聚酰亚胺（PI）在航空航天等高科技领域引起了广泛关注。与此同时，创建包含 PI 的三维 (3D) 形状记忆结构的材料和方法仍然是一项紧迫的任务。在这项工作中，我们开发了基于高性能易溶 PI、反应性溶剂（N,N-二甲基丙烯酰胺）和光活性交联剂（双酚 A 乙氧基化物二丙烯酸酯 (BAEDA) 或 [2-(丙烯酰氧基)乙基]异氰脲酸酯(TAI))。由此产生的 PPC 用于通过 LCD 3D 打印形成 3D 结构。研究发现，交联剂的性质和后加工温度对材料的热性能和机械性能有显着影响。在250°С热后固化1小时后，拉伸强度达到最大值（含有TAI和BAEDA的PPC分别为83.3±7.4MPa和60.8±4.8MPa）。此外，4D打印的含PI材料在恢复温度>150℃时表现出优异的形状记忆性能，形状固定率>99%，形状恢复率高达95.6%。