Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611, USA.
Department of Chemistry, University of Florida, Gainesville, FL 32611, USA.
Sci Adv. 2017 May 10;3(5):e1602800. doi: 10.1126/sciadv.1602800. eCollection 2017 May.
The widespread prevalence of commercial products made from microgels illustrates the immense practical value of harnessing the jamming transition; there are countless ways to use soft, solid materials that fluidize and become solid again with small variations in applied stress. The traditional routes of microgel synthesis produce materials that predominantly swell in aqueous solvents or, less often, in aggressive organic solvents, constraining ways that these exceptionally useful materials can be used. For example, aqueous microgels have been used as the foundation of three-dimensional (3D) bioprinting applications, yet the incompatibility of available microgels with nonpolar liquids, such as oils, limits their use in 3D printing with oil-based materials, such as silicone. We present a method to make micro-organogels swollen in mineral oil, using block copolymer self-assembly. The rheological properties of this micro-organogel material can be tuned, leveraging the jamming transition to facilitate its use in 3D printing of silicone structures. We find that the minimum printed feature size can be controlled by the yield stress of the micro-organogel medium, enabling the fabrication of numerous complex silicone structures, including branched perfusable networks and functional fluid pumps.
广泛存在的由微凝胶制成的商业产品说明了利用凝胶化转变的巨大实际价值；有无数种方法可以使用软的、固态的材料，这些材料在施加的应力稍有变化时就会流态化并再次变成固态。传统的微凝胶合成方法主要产生在水溶剂中溶胀的材料，或者在较不常见的情况下在腐蚀性有机溶剂中溶胀，限制了这些非常有用的材料的使用方式。例如，水凝胶已被用作三维（3D）生物打印应用的基础，但现有微凝胶与非极性液体（如油）的不兼容性限制了它们在基于油的材料（如硅酮）的 3D 打印中的使用。我们提出了一种使用嵌段共聚物自组装来制备在矿物油中溶胀的微有机凝胶的方法。可以利用凝胶化转变来调整这种微有机凝胶材料的流变性能，使其易于用于硅酮结构的 3D 打印。我们发现，最小打印特征尺寸可以通过微有机凝胶介质的屈服应力来控制，从而能够制造出许多复杂的硅酮结构，包括分支可灌注网络和功能流体泵。
