Xu Weinan, Qin Zhao, Chen Chun-Teh, Kwag Hye Rin, Ma Qinli, Sarkar Anjishnu, Buehler Markus J, Gracias David H
Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA.
Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Sci Adv. 2017 Oct 6;3(10):e1701084. doi: 10.1126/sciadv.1701084. eCollection 2017 Oct.
Graphene and other two-dimensional materials have unique physical and chemical properties of broad relevance. It has been suggested that the transformation of these atomically planar materials to three-dimensional (3D) geometries by bending, wrinkling, or folding could significantly alter their properties and lead to novel structures and devices with compact form factors, but strategies to enable this shape change remain limited. We report a benign thermally responsive method to fold and unfold monolayer graphene into predesigned, ordered 3D structures. The methodology involves the surface functionalization of monolayer graphene using ultrathin noncovalently bonded mussel-inspired polydopamine and thermoresponsive poly(-isopropylacrylamide) brushes. The functionalized graphene is micropatterned and self-folds into ordered 3D structures with reversible deformation under a full control by temperature. The structures are characterized using spectroscopy and microscopy, and self-folding is rationalized using a multiscale molecular dynamics model. Our work demonstrates the potential to design and fabricate ordered 3D graphene structures with predictable shape and dynamics. We highlight applicability by encapsulating live cells and creating nonlinear resistor and creased transistor devices.
石墨烯和其他二维材料具有广泛相关的独特物理和化学性质。有人提出，通过弯曲、起皱或折叠将这些原子平面材料转变为三维（3D）几何形状，可能会显著改变它们的性质，并导致具有紧凑外形的新型结构和器件，但实现这种形状变化的策略仍然有限。我们报告了一种温和的热响应方法，可将单层石墨烯折叠和展开成预先设计的有序3D结构。该方法涉及使用超薄非共价键合的贻贝启发的聚多巴胺和热响应性聚（N-异丙基丙烯酰胺）刷对单层石墨烯进行表面功能化。功能化的石墨烯经过微图案化处理，并在温度的完全控制下自折叠成具有可逆变形的有序3D结构。使用光谱学和显微镜对这些结构进行表征，并使用多尺度分子动力学模型对自折叠过程进行合理化解释。我们的工作展示了设计和制造具有可预测形状和动力学的有序3D石墨烯结构的潜力。我们通过封装活细胞以及制造非线性电阻器和褶皱晶体管器件来突出其适用性。
