Department of Chemistry and Macromolecules Innovation Institute (MII), Virginia Tech, Blacksburg, VA, 24061, USA.
Department of Mechanical Engineering and Macromolecules Innovation Institute (MII), Virginia Tech, Blacksburg, VA, 24061, USA.
Adv Mater. 2017 Aug;29(31). doi: 10.1002/adma.201701240. Epub 2017 Jun 19.
High-performance, all-aromatic, insoluble, engineering thermoplastic polyimides, such as pyromellitic dianhydride and 4,4'-oxydianiline (PMDA-ODA) (Kapton), exhibit exceptional thermal stability (up to ≈600 °C) and mechanical properties (Young's modulus exceeding 2 GPa). However, their thermal resistance, which is a consequence of the all-aromatic molecular structure, prohibits processing using conventional techniques. Previous reports describe an energy-intensive sintering technique as an alternative technique for processing polyimides with limited resolution and part fidelity. This study demonstrates the unprecedented 3D printing of PMDA-ODA using mask-projection stereolithography, and the preparation of high-resolution 3D structures without sacrificing bulk material properties. Synthesis of a soluble precursor polymer containing photo-crosslinkable acrylate groups enables light-induced, chemical crosslinking for spatial control in the gel state. Postprinting thermal treatment transforms the crosslinked precursor polymer to PMDA-ODA. The dimensional shrinkage is isotropic, and postprocessing preserves geometric integrity. Furthermore, large-area mask-projection scanning stereolithography demonstrates the scalability of 3D structures. These unique high-performance 3D structures offer potential in fields ranging from water filtration and gas separation to automotive and aerospace technologies.
高性能、全芳香族、不溶、工程热塑性聚酰亚胺，如均苯四酸二酐和 4,4'-二氨基二苯醚（PMDA-ODA）（Kapton），表现出优异的热稳定性（高达约 600°C）和机械性能（杨氏模量超过 2 GPa）。然而，它们的耐热性是全芳香族分子结构的结果，禁止使用传统技术进行加工。以前的报告描述了一种能量密集型的烧结技术作为加工聚酰亚胺的替代技术，但分辨率和零件保真度有限。本研究使用掩模投影立体光刻技术展示了 PMDA-ODA 的前所未有的 3D 打印，并且在不牺牲体材料性能的情况下制备了高分辨率的 3D 结构。合成含有光交联性丙烯酸酯基团的可溶性前体聚合物，使光引发的化学交联能够在凝胶状态下进行空间控制。后印刷热处理将交联的前体聚合物转化为 PMDA-ODA。尺寸收缩是各向同性的，后处理保持了几何完整性。此外，大面积掩模投影扫描立体光刻展示了 3D 结构的可扩展性。这些独特的高性能 3D 结构在从水过滤和气体分离到汽车和航空航天技术等领域具有潜在应用。
