Polyimide (PI), an important engineering polymer with a rigid chemical structure, readily has excellent chemical stability, heat resistance, and electrical insulation but lacks broadband photothermal properties. Herein, we design and synthesize PI copolymers that embrace intrinsic photothermal properties by using two diamine monomers of (Z)-2,3-bis(4-aminophenyl) acrylonitrile (CNDA) and 4,4-diphenyldiamine (NDA) with strong ultraviolet (UV), and near-infrared (NIR) absorption capabilities, respectively. Tuning the molar ratio of the two diamines can modulate UV and NIR light absorption and regulate the intrinsic photothermal properties of PIs. After condensation with pyromellitic dianhydride, the resulting PI-0.5 with a unit molar ratio of CNDA:NDA = 1 shows the best photothermal efficiency. PI-0.5 is used to construct 3D steam generators with vertically dried channels by a freeze-drying method. The 3D steam generators show a good water evaporation rate and continuously operate with excellent stability under varying salinity and pH conditions. The synthetic design herein suggests that PI can be molecularly engineered to be intrinsic photothermal materials, expanding the properties and applications of existing PIs.

中文翻译：

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聚酰亚胺吸光共聚物作为太阳能水蒸发的高效光热材料

聚酰亚胺（PI）是一种重要的工程聚合物，具有刚性的化学结构，具有优异的化学稳定性、耐热性和电绝缘性，但缺乏宽带光热性能。在此，我们通过使用具有强紫外线的(Z)-2,3-双(4-氨基苯基)丙烯腈(CNDA)和4,4-二苯二胺(NDA)两种二胺单体设计并合成了具有固有光热性能的PI共聚物。分别具有吸收能力（UV）和近红外（NIR）。调节两种二胺的摩尔比可以调节紫外和近红外光吸收并调节 PI 的固有光热性质。与均苯四甲酸二酐缩合后，单位摩尔比CNDA:NDA=1的PI-0.5表现出最佳的光热效率。PI-0.5用于通过冷冻干燥方法构建具有垂直干燥通道的3D蒸汽发生器。3D 蒸汽发生器表现出良好的水蒸发率，并在不同的盐度和 pH 条件下连续运行，具有出色的稳定性。本文的合成设计表明，PI 可以通过分子工程改造成为本征光热材料，从而扩展现有 PI 的性能和应用。