We love what we do. Especially when reviewing cutting edge research and find that the Scientists Create World’s Lightest 3D Printed Materials – Graphene Aerogel are our long time customers!
‘We developed a novel 3D printing technique, as illustrated in Figure 1 , by integrating 3D printing ice and freeze casting to print GA. Different from other 3D printing processes where the materials are heated up or extruded out at room temperature, our 3D printing technique, illustrated in Figure 1 a, rapidly freezes the water based GO suspension and selectively solidifi es the aqueous droplets into ice crystal on a cold sink (−25 °C), well below water’s freezing point. Therefore, the water, shown in Figure 1 b, and low viscous Newtonian GO suspension, shown in Figure 1 c, can be printed by drop-on-demand mode, where the material is ejected drop by drop only if needed. The dilute pure aqueous GO suspension, with low GO density (1 mg mL −1 ), offers lower density and larger surface area for printed GA when compared with the-state-of-the-art printing technique for GA. In traditional continuous deposition based 3D printing, physical properties of printed parts are negatively influenced by insufficient bonding at the interface driven by intermolecular diffusion and the undesirable voids between the adjacent filaments.
In our printing process, when liquid solution is deposited on top of previously frozen material, the not-yet-frozen material melts the already frozen surface. These two materials are mixed and refrozen together under low temperature (−25 °C). Because the remelted aqueous material possesses low viscosity, the voids between layers are instantly filled by the liquid material under surface tension and gravity. Since the deposited materials freeze and firmly bond together with the previous layer via hydrogen bond, high structural integrity of the final assembled GA can be achieved, as further confirmed in the mechanical test section. The pure water serves as a supporting structure to build complex architecture with overhang features. As shown in Figure 1 d–f, the post processing includes immersion of 3D printed architectures in liquid nitrogen, freeze drying to remove the water, and thermal annealing to achieve a 3D printed ultralight GA truss. As shown in Figure 1 g, 2.5 D (left) and truly 3D truss (right), GO aerogel structure can be printed. We also printed grid GO aerogel structures with various wall thicknesses, decreasing from left to right in Figure 1 h, in order to demonstrate the printing ability. Figure S1a–c (Supporting Information) illustrates more 3D printed GO aerogels on catkin and Figure S1d–f (Supporting Information) shows various design and structures with different wall thicknesses. Compared to the continuous printing mode, the drop-on-demand technique achieves higher precision and is easier to extend for printing multiple materials with multinozzles, paving the way for fabrication of multifunctional aerogel materials in myriad applications.”
The full journal article can be purchased at the link http://onlinelibrary.wiley.com/doi/10.1002/smll.201503524/abstract