3D Printing All‐Aromatic Polyimides using Mask‐Projection Stereolithography: Processing the Nonprocessable

Abstract

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.

3D Printing Amorphous Polysiloxane Terpolymers via Vat Photopolymerization

“…Integration of these curves yielded overall polymerization exotherm, which remained nearly constant at 12–13 W g −1 as a function of photoinitiator concentration for all samples tested (data not shown). Figure B displays time to reach heat flow maxima (s), corresponding to the maximum rate of polymerization ( R p max ), as a function of photoinitiator concentration, which reached a plateau value at the highest photoinitiator concentrations (≈1 wt%), consistent with trends described in the literature . Figure C shows shear storage modulus ( G ′) as a function of irradiation time from photorheology of the DiPhS + SH system, reaching a plateau value () more rapidly with increasing photoinitiator concentration.…”

“…Figure 2B , as a function of photoinitiator concentration, which reached a plateau value at the highest photoinitiator concentrations (≈1 wt%), consistent with trends described in the literature. [39] Figure 2C shows shear storage modulus (G′) as a function of irradiation time from photorheology of the DiPhS + SH system, reaching a plateau value (G N 0 ) more rapidly with increasing photoinitiator concentration. Finally, Figure 2D presents storage (G′) and loss (G″) modulus crossover, which were shown earlier to indicate gel point for stoichiometrically balanced systems far above T g , [42] as a function of photoinitiator concentration.…”

“…All VP information, including methods for generating the photopolymer working curve, is provided elsewhere …”

High‐Performance Materials for 3D Printing in Chemical Synthesis Applications

“…[17][18][19] Heterogeneous reactions can run more efficiently in microfluidic format due to the large surface-tovolume ratios that ensure improved phase contact and heating is much easier controllable on the microscale which significantly enhances the yield of temperature-sensitive reactions. [26,27] Additionally, it has been shown that the polymeric materials often strongly influence the success of the reaction. [21] 3D printing technologies have also been used for the fabrication of low-volume chemical batch or flow-through synthesis reactors.…”

“…[22,25] Most regular materials for SL are acrylic-or epoxy-based possessing low chemical and thermal stability, 3D-printed polytetrafluoroethylene (PTFE), and polyimides being a notable exception. [26,27] Additionally, it has been shown that the polymeric materials often strongly influence the success of the reaction. [24] Thus, there is a need for novel highly resistant materials for SL.…”