Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208, USA.
International Institute for Nanotechnology, Northwestern University, Evanston, IL 60208, USA.
Sci Adv. 2023 Sep 29;9(39):eadj8103. doi: 10.1126/sciadv.adj8103.
Lattice-based constructs, often made by additive manufacturing, are attractive for many applications. Typically, such constructs are made from microscale or larger elements; however, smaller nanoscale components can lead to more unusual properties, including greater strength, lighter weight, and unprecedented resiliencies. Here, solid and hollow nanoparticles (nanoframes and nanocages; frame size: ~15 nanometers) were assembled into colloidal crystals using DNA, and their mechanical strengths were studied. Nanosolid, nanocage, and nanoframe lattices with identical crystal symmetries exhibit markedly different specific stiffnesses and strengths. Unexpectedly, the nanoframe lattice is approximately six times stronger than the nanosolid lattice. Nanomechanical experiments, electron microscopy, and finite element analysis show that this property results from the buckling, densification, and size-dependent strain hardening of nanoframe lattices. Last, these unusual open architectures show that lattices with structural elements as small as 15 nanometers can retain a high degree of strength, and as such, they represent target components for making and exploring a variety of miniaturized devices.
基于格子的结构，通常通过增材制造制成，对于许多应用具有吸引力。通常，这种结构由微尺度或更大的元件制成；然而，更小的纳米尺度组件可以带来更不寻常的特性，包括更高的强度、更轻的重量和前所未有的弹性。在这里，使用 DNA 将实心和空心纳米粒子（纳米框架和纳米笼；框架尺寸：约 15 纳米）组装成胶体晶体，并研究了它们的机械强度。具有相同晶体对称性的纳米实心晶格、纳米笼晶格和纳米框架晶格具有明显不同的比刚度和强度。出乎意料的是，纳米框架晶格的强度约为纳米实心晶格的六倍。纳米力学实验、电子显微镜和有限元分析表明，这种特性源于纳米框架晶格的屈曲、致密化和尺寸相关的应变硬化。最后，这些不寻常的开放式结构表明，结构元件小至 15 纳米的晶格可以保持高强度，因此它们是制造和探索各种小型化设备的目标组件。
