Additive-Free Aerogel 3D Printing Using Ultra-Low Storage Modulus Inks

Abstract

State-of-the-art aerogels, when crafted through 3D printing, exhibit remarkable properties and innovative functionalities. Yet, printing additive-free aerogels with excellent intrinsic properties remains a challenge. Here a rheology matching strategy is introduced that effectively resolves this issue. Importantly, this strategy not only mitigates the negative effects of rapidly evolving resorcinol (R)-formaldehyde (F) sol-gel rheology, but also prevents the gravitational and capillary slumping. This breakthrough enables the 3D printing of additive-free RF aerogels using an ink with ultra-low storage modulus (≈2 Pa, the lowest record for aerogel-based inks) and a fluid-like loss factor (tan α >1). These additive-free prints perfectly retain intrinsic properties of aerogels, showing uniform nanostructure and high specific surface area of up to 836.1 m² g⁻¹, which is significantly superior to conventional prints that incorporate additives. Moreover, the flexibility in 3D design extends the application range for advanced aerogels. Consequently, well-designed aerogel-based solar steam generation devices demonstrate competitive evaporation rates of 1.85–2.30 kg m⁻² h⁻¹. This protocol broadens the scope of printable rheology for aerogel 3D printing and enables the fabrication of aerogel objects with intrinsic properties and large-span overhanging features, which opens up new possibilities for the 3D construction of various aerogels across diverse applications.