Electro-manipulating of negative-charged aramid nanofibers towards micro-to-macro scale colloidal aerogel films.

Aerogels, often hailed as the world-changing magic nanoporous material, are traditionally synthesized through reagent-induced sol-gel transitions. However, the uncontrolled random motion of molecular/colloidal precursors poses significant challenges in achieving precise structural control of aerogel. In this study, we present an unprecedented electro-manipulation strategy, easy to be applied in batch-run as well as roll-to-roll processes, to engineer well-defined micro-/macro-structured aerogel films. By leveraging electrophoresis-driven self-assembly and electrochemistry-driven gelation of negatively charged aramid nanofibers in sequence, we demonstrate large-area (50 cm × 50 cm) as well as continuous (up to 20 meters in length) fabrications of aramid colloidal aerogel films with patterned microstructures and programmable nanofiber orientation. These features effectively enhance the performance of the resulting colloidal aerogel films such as mechanical strength, thermal insulation and proton conduction, and show their broad applications in various fields. This work presents an effective strategy for precise aerogel structure regulation through external field manipulation.