Yulaev Alexander, Lipatov Alexey, Lu Annie Xi, Sinitskii Alexander, Leite Marina S, Kolmakov Andrei
Center for Nanoscale Science and Technology, NIST, 100 Bureau Drive, Gaithersburg, MD 20899-6204 USA.
Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742 USA.
Adv Funct Mater. 2017 Jan 23;4(2). doi: 10.1002/admi.201600734. Epub 2016 Dec 1.
We demonstrate a technique for facile encapsulation and adhesion of micro- and nano objects on arbitrary substrates, stencils, and micro structured surfaces by ultrathin graphene oxide membranes via a simple drop casting of graphene oxide solution. A self-assembled encapsulating membrane forms during the drying process at the liquid-air and liquid-solid interfaces and consists of a water-permeable quasi-2D network of overlapping graphene oxide flakes. Upon drying and interlocking between the flakes, the encapsulating coating around the object becomes mechanically robust, chemically protective, and yet highly transparent to electrons and photons in a wide energy range, enabling microscopic and spectroscopic access to encapsulated objects. The characteristic encapsulation scenarios were demonstrated on a set of representative inorganic and organic micro and nano-objects and microstructured surfaces. Different coating regimes can be achieved by controlling the pH of the supporting solution, and the hydrophobicity and morphology of interfaces. Several specific phenomena such as compression of encased objects by contracting membranes as well as hierarchical encapsulations were observed. Finally, electron as well as optical microscopy and analysis of encapsulated objects along with the membrane effect on the image contrast formation, and signal attenuation are discussed.
我们展示了一种通过氧化石墨烯溶液的简单滴铸法，利用超薄氧化石墨烯膜将微米和纳米物体轻松封装并粘附在任意基底、模板和微结构表面上的技术。在液 - 气和液 - 固界面的干燥过程中会形成一种自组装封装膜，它由重叠的氧化石墨烯薄片构成的透水准二维网络组成。干燥后，薄片之间相互锁定，物体周围的封装涂层在机械性能上变得坚固，具有化学保护作用，并且在很宽的能量范围内对电子和光子具有高度透明性，从而能够对封装物体进行微观和光谱观察。在一组具有代表性的无机和有机微米及纳米物体以及微结构表面上展示了典型的封装情况。通过控制支撑溶液的pH值以及界面的疏水性和形态，可以实现不同的涂层状态。观察到了一些特定现象，如收缩膜对被包裹物体的压缩以及分层封装。最后，讨论了电子显微镜和光学显微镜对封装物体的观察与分析，以及膜对图像对比度形成和信号衰减的影响。
