State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing 211816, China.
J Phys Chem B. 2020 Dec 3;124(48):10961-10970. doi: 10.1021/acs.jpcb.0c07147. Epub 2020 Nov 17.
The behavior of liquids in two-dimensional (2-D) graphene oxide (GO) nanopores is important for developing GO-based nanoscience and nanofluidics. Herein, molecular dynamics simulation was carried out to study the equilibrium structures and shear viscosity for water and ethanol confined within 2-D GO nanochannels. It was observed that both species obviously exhibit structured features near GO surfaces. The confined viscosities are anisotropic with axial shear viscosity larger than vertical viscosity. The axial shear viscosities of water and ethanol are greatly enhanced for the 2-D GO nanochannels, wherein the viscosity features a decreased pattern with the pore width. Compared with water molecules, the confinement of GO channels has more effect on the viscosity of ethanol molecules. The confined shear viscosity can be described by combining contributions of the interfacial layer viscosity and the bulk-like viscosity. The influences of oxidation degrees and pore widths on the structure and transport properties have been systematically investigated, in which the interlayer viscosity is the critical determining factor. The confined structures and surface interaction were applied to interpret the transport properties of confined liquids. The enhanced interfacial layer viscosity can be attributed to the surface hydrogen-bonding interaction arising from the oxygen-containing functional groups.
二维（2-D）氧化石墨烯（GO）纳米孔中液体的行为对于开发基于 GO 的纳米科学和纳流控至关重要。在此，通过分子动力学模拟研究了受限在 2-D GO 纳米通道内的水和乙醇的平衡结构和剪切黏度。结果表明，两种物质在 GO 表面附近均表现出明显的结构化特征。受限黏度具有各向异性，轴向剪切黏度大于垂直黏度。2-D GO 纳米通道中水和乙醇的轴向剪切黏度显著增强，其中黏度随孔径减小而降低。与水分子相比，GO 通道的限制对乙醇分子的黏度有更大的影响。受限剪切黏度可以通过界面层黏度和类体黏度贡献的组合来描述。系统研究了氧化程度和孔径对结构和输运性质的影响，其中层间黏度是关键决定因素。受限结构和表面相互作用被应用于解释受限液体的输运性质。界面层黏度的增强归因于含氧官能团引起的表面氢键相互作用。
