Liu Yi, Consta Styliani, Goddard William A
Materials and Process Simulation Center (M/C 139-74), California Institute of Technology, 1200 East California Blvd., Pasadena, California 91125, USA.
J Nanosci Nanotechnol. 2010 Jun;10(6):3834-43. doi: 10.1166/jnn.2010.1999.
Despite the continuing research interests in CNT-liquid systems, the microscopic structure and transport behavior of liquid mixtures in carbon nanotubes (CNTs) remain poorly understood. Methanol and water liquids are completely miscible across the entire range of concentration; however, recent research reveals that they are immiscible at a molecular level. In this work, we carried out classical molecular dynamics to study the molecular distribution, structure ordering, clustering and transport behavior of liquid methanol-water mixtures within CNT confinement. We found that CNTs preferentially absorbed methanol over water molecule even though the latter has a smaller molecular size, indicating that chemical effect such as molecular hydrophilicity plays a crucial role in the molecular absorption of CNTs. Due to the selective absorption of CNTs, methanol aqueous solution changes from microscopically immiscible to macroscopically immiscible at nanoscale. This nanoscale immiscibility may be utilized in various applications of CNTs including direct methanol fuel cells, nanosensors, molecular sieves, nanofluidic chips, and capsules for drug delivery.
尽管对碳纳米管-液体体系的研究兴趣持续存在，但碳纳米管（CNTs）中液体混合物的微观结构和传输行为仍知之甚少。甲醇和水在整个浓度范围内完全互溶；然而，最近的研究表明，它们在分子水平上是不互溶的。在这项工作中，我们进行了经典分子动力学模拟，以研究受限在碳纳米管内的液态甲醇-水混合物的分子分布、结构有序性、聚集和传输行为。我们发现，尽管水分子尺寸较小，但碳纳米管优先吸收甲醇分子，这表明诸如分子亲水性等化学效应在碳纳米管的分子吸收中起着关键作用。由于碳纳米管的选择性吸收，甲醇水溶液在纳米尺度上从微观不互溶变为宏观不互溶。这种纳米尺度的不互溶性可用于碳纳米管的各种应用，包括直接甲醇燃料电池、纳米传感器、分子筛、纳米流体芯片和药物递送胶囊。
