Direct Ink Writing Additive Manufacturing of Silica Aerogels

Silica aerogels (SAs) have garnered significant attention due to their high porosity, low density, hydrophobic properties, low thermal conductivity, and optical transparency. The traditional method for producing SAs, known as "sol-gel" technology, involves precursor preparation, aging, and drying processes. However, aerogels produced through this method often exhibit drawbacks such as poor processability and low precision, which prevent them from fully leveraging their potential properties, including catalysis, adsorption, insulation, and sensing. In contrast, direct ink writing (DIW) technology offers a promising avenue for creating functional structures from SAs. This technique enables the production of inks with shear-thinning behavior, facilitating the high-precision printing of complex SA structures. This review summarizes the advancements in DIW additive manufacturing (AM) of SAs and the challenges currently faced in this field. Briefly, we first introduce the ink preparation, 3D printing process, drying and heat treatment suitable for DIW 3D printing of silica aerogels, followed by the discussion of the current state of research and key challenges of DIW 3D printing SAs.