Cote Laura J, Kim Franklin, Huang Jiaxing
Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA.
J Am Chem Soc. 2009 Jan 28;131(3):1043-9. doi: 10.1021/ja806262m.
Single-layer graphite oxide can be viewed as an unconventional type of soft material and has recently been recognized as a promising material for composite and electronics applications. It is of both scientific curiosity and technical importance to know how these atomically thin sheets assemble. There are two fundamental geometries of interacting single layers: edge-to-edge and face-to-face. Such interactions were studied at the air-water interface by Langmuir-Blodgett assembly. Stable monolayers of graphite oxide single layers were obtained without the need for any surfactant or stabilizing agent, due to the strong electrostatic repulsion between the 2D confined layers. Such repulsion also prevented the single layers from overlapping during compression, leading to excellent reversibility of the monolayers. In contrast to molecular and hard colloidal particle monolayers, the single layers tend to fold and wrinkle at edges to resist collapsing into multilayers. The monolayers can be transferred to a substrate, readily creating a large area of flat graphite oxide single layers. The density of such films can be continuously tuned from dilute, close-packed to overpacked monolayers of interlocking single layers. For size-mismatched single layers, face-to-face interaction caused irreversible stacking, leading to double layers. The graphite oxide monolayers can be chemically reduced to graphene for electronic applications such as transparent conducting thin films.
单层氧化石墨烯可被视为一种非常规类型的软材料，最近已被公认为是用于复合材料和电子应用的一种有前途的材料。了解这些原子级薄片如何组装既具有科学趣味性又具有技术重要性。相互作用的单层有两种基本几何结构：边对边和面对面。通过朗缪尔-布洛杰特组装法在空气-水界面研究了此类相互作用。由于二维受限层之间强烈的静电排斥作用，无需任何表面活性剂或稳定剂就能获得稳定的氧化石墨烯单层。这种排斥作用还防止了单层在压缩过程中重叠，从而使单层具有出色的可逆性。与分子和硬胶体颗粒单层不同，单层在边缘处倾向于折叠和起皱以防止塌陷成多层。单层可以转移到基底上，轻松形成大面积的平整氧化石墨烯单层。此类薄膜的密度可以从稀疏、紧密堆积连续调节到互锁单层的过密堆积单层。对于尺寸不匹配的单层，面对面相互作用会导致不可逆堆积，形成双层。氧化石墨烯单层可以化学还原为石墨烯，用于诸如透明导电薄膜等电子应用。
