Versatile Direct Writing of Aerogel-Based Sol–Gel Inks

Abstract

Direct ink writing (DIW) of aerogels has great potential in designing novel three-dimensional (3D) multifunctional materials with hierarchical structures ranging from the nanoscale to the macroscopic scale. In this paper, pure aerogels composed of inorganics, strongly cross-linking organics, and weakly cross-linking organics were directly written via the precise control of the gelation degree without using any additives. The rheological properties of a resorcinol–formaldehyde aerogel-based sol–gel ink (marked as RA ink) were measured at different reaction times to determine the suitable printable range (G′LVR: several 103 Pa) that ensures its good print fidelity. In addition, the rheological evolution of the RA ink during the sol–gel process and under different shear stresses was studied. The correlation of relevant parameters was established according to the Hagen–Poiseuille model. Other typical aerogel-based sol–gel inks including a silica aerogel-based sol–gel ink (SA ink) and a polyimide aerogel-based sol–gel ink (PA ink) for DIW were also demonstrated. Finally, water evaporation experiments were carried out using a 3D-printed carbonized resorcinol–formaldehyde aerogel (CA) to further exhibit the potential applications of this novel technology in solar steam generation. The evaporation rate (1.57 kg m–2 h–1) and efficiency (88.38%) of 3D-printed CA were higher than those of bulk CA (1.21 kg m–2 h–1 and 69.82%). This paper systematically studies the control of DIW parameters for aerogel-based sol–gel inks and shows a potential application in high-efficiency 3D-printed evaporators.

Dual-Functional Graphene Oxide-Based Photothermal Materials with Aligned Channels and Oleophobicity for Efficient Solar Steam Generation

“…Nowadays, global warming and industrial pollution are becoming a more and more serious concern . People are forced to pay attention to the serious shortage of freshwater resources. − Traditional seawater desalination technologies, such as reverse osmosis (RO), , microfiltration, , ultrafiltration, , multieffect distillation, , multistage flash evaporation, adsorption, , etc., have the limitations of low efficiency, high cost, redundant operation, and huge energy consumption, which aggravate the greenhouse effect and environmental pollution, thus hindering their large-scale applications. Therefore, effective production of freshwater using clean energy as the input through a much more practical way should be a priority.…”

Additive Manufacturing of 3D Aerogels and Porous Scaffolds: A Review

“…[29] Accordingly, a vast majority of the studies on 3D-printed aerogels using EBP uses pneumatic pressure driven extrusion setups. Only a few studies incorporate mechanical [24,51,54,[59][60][61][62][63][64][65][66] and screw-based [33,67,68] extrusion systems among more than 50 studies that report 3D-printed aerogels using an EBP setup. Commonly, ink formulations are water-based, and they do not require elevated temperatures to achieve material extrusion as in fused deposition modelling.…”

“…3D‐printed carbon aerogels based on R‐F ink and showed how the macroscopic pores affect the solar steam generation performance. [ 66 ] The 3D‐printed carbon aerogels had a water evaporation rate of 1.57 kg m −2 under 1 sun illumination, and evaporation efficiency of 88.38%. The significantly high evaporation rate and efficiency is attributed to the better contact between the aerogel and light achieved after macroscopic porosity introduced by 3D printing technology.…”

Review of Fiber-Based Three-Dimensional Printing for Applications Ranging from Nanoscale Nanoparticle Alignment to Macroscale Patterning

“…DIW of an aerogel is another strategy often used to construct hierarchical structures across the nanoscale and macroscale. − Du’s group demonstrated DIW of different types of aerogel-based inks, with the highest specific surface area reaching 613 m 2 g –1 for a resorcinol–formaldehyde aerogel . Similar to multimaterial printing in 1D fibers or 2D surfaces, 3D scaffolds also benefit from using different materials to achieve multifunctional performances.…”