Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, AB, T2N 1N, Canada.
Department of Mechanical and Aerospace Engineering Princeton University, Princeton, NJ, 08544, USA.
Nat Commun. 2022 Jul 18;13(1):4162. doi: 10.1038/s41467-022-31644-2.
Printing a structured network of functionalized droplets in a liquid medium enables engineering collectives of living cells for functional purposes and promises enormous applications in processes ranging from energy storage to tissue engineering. Current approaches are limited to drop-by-drop printing or face limitations in reproducing the sophisticated internal features of a structured material and its interactions with the surrounding media. Here, we report a simple approach for creating stable liquid filaments of silica nanoparticle dispersions and use them as inks to print all-in-liquid materials that consist of a network of droplets. Silica nanoparticles stabilize liquid filaments at Weber numbers two orders of magnitude smaller than previously reported in liquid-liquid systems by rapidly producing a concentrated emulsion zone at the oil-water interface. We experimentally demonstrate the printed aqueous phase is emulsified in-situ; consequently, a 3D structure is achieved with flexible walls consisting of layered emulsions. The tube-like printed features have a spongy texture resembling miniaturized versions of "tube sponges" found in the oceans. A scaling analysis based on the interplay between hydrodynamics and emulsification kinetics reveals that filaments are formed when emulsions are generated and remain at the interface during the printing period. Stabilized filaments are utilized for printing liquid-based fluidic channels.
在液体介质中打印功能化的结构化液滴网络，可用于对活细胞进行功能工程化设计，在从能量存储到组织工程等一系列过程中具有巨大的应用潜力。目前的方法仅限于逐滴打印，或者在复制结构化材料的复杂内部特征及其与周围介质的相互作用方面存在局限性。在这里，我们报告了一种简单的方法，可用于制造稳定的二氧化硅纳米颗粒分散体的液体细丝，并将其用作墨水，以打印由液滴网络组成的全液相材料。二氧化硅纳米颗粒通过在油水界面上迅速产生浓缩乳液区，将韦伯数稳定在比先前报道的液-液系统小两个数量级的液体细丝中，从而达到稳定的效果。我们通过实验证明了所打印的水相是原位乳化的；因此，通过分层乳液形成具有柔性壁的 3D 结构。打印的管状特征具有海绵状的质地，类似于在海洋中发现的“管状海绵”的微型版本。基于流体动力学和乳化动力学之间相互作用的标度分析表明，当乳液生成时，细丝会形成并在打印过程中保持在界面上。稳定的细丝可用于打印基于液体的流体通道。
