Direct-write 3D printing of polyimide-silica aerogel composites

The specific geometry has a crucial impact on the function of aerogel materials in application scenarios. However, conventional manufacturing technology remains challenging in the customized shaping of aerogels due to the fragility of aerogels, time-consuming manufacturing cycles, and poor designability of molds. Direct-write 3D printing technology has been applied to achieve the on-demand shaping of aerogels, imparting aerogels with compatible material composition and functional characteristics. In this work, a direct-write 3D printing strategy based on dual-channel intermixing extrusion was proposed to prepare polyimide-silica (OBS) aerogel composites. Benefiting from the efficient fluid diffusion intermixing between inks and catalysts during extrusion processes, chemical imidization solidification can be successfully achieved, and 3D-printed OBS aerogel composites show high structural integrity and high shape fidelity. Depending on the advantages of the spatial assembly of direct-write 3D printing technology, OBS aerogel composites have formed multi-scale morphologies of millimeters, micrometers, and nanometers. In micron scale, the composite structure enables 3D-printed OBS aerogel composites to display excellent mechanical properties (Young's modulus up to 14.4 MPa). Meanwhile, nanoscale pore structure features, such as low density (0.208 g·cm−3), high surface area (373 m2·g−1), and concentrated poren diameter distribution (20-30 nm), impart 3D-printed OBS aerogel composites with excellent thermal insulation performance (thermal conductivity as low as 21.25 mW·m−1·K−1). Although our work only focuses on OBS aerogel composites, the successful implementation of this 3D printing strategy would provide guidelines for additive manufacturing of other aerogel composites. © 2024 Beijing University of Aeronautics and Astronautics (BUAA). All rights reserved.