Green Synthesis of Vat Photopolymerization 3D Printing Polyimide

Vat photopolymerization (VP) 3D printing polyimide (PI) has the combined advantages of 3D printing in free-form manufacturing and PI in comprehensive properties. While, the inks for VP 3D printing PI are generally involve in complicated synthesis process of photosensitive oligomers or precursors, which undoubtedly result in serious environmental issues because of significant amounts of solvents and wastewater during the precipitation and purification. Here, a VP 3D printing PI is designed via a novel one-pot environmentally-friendly approach with reactive dilute N-vinyl pyrrolidinone (NVP) as the solvent. NVP, similar to the conventional solvent N-methyl pyrrolidinone (NMP) used for PI synthesis, serves as the solvent during synthesizing the precursor double-bonds containing amide-acid while functions as the reactive diluent directly in the final photosensitive ink, thereafter, generating not even a drop of waste solvent or water because needless of precipitation of oligomers as usual. The resultant inks show good printability and low shrinkage of 11%, resulting in architectures with precision and complex structures, excellent thermal and mechanical performance of glass transition temperature (233.1 °C) and tensile strength (58.1 MPa), respectively. The method paves the green way for developing PI 3D architectures and functional devices, demonstrating significant potential in aerospace, microelectronics, and many others.