Molecular dynamics simulation of a single polymer in hydrophilic nano-slits  

作　　者：REN Ying GAO Jian GE Wei LI JingHai HU GuoHua 

机构地区：[1]State Key Laboratory of Multiphase Complex System, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100090, China [2]Graduate University of the Chinese Academy of Sciences, Beijing 100039, China [3]Laboratory of Chemical Engineering Sciences, CNRS-ENSIC-INPL, 1 rue Grandville, BP 20451, Nancy 54001, France

出　　处：《Chinese Science Bulletin》2008年第17期2599-2606,共8页

基　　金：the National Natural Science Foundation of China (Grant Nos. 20336040, 20490201 and 20221603);Chinese Academy of Sciences (Grant Nos. KJCX-SW-L01 and KJCX3-SYW-S01);Research Fund of Key Lab for Nanomaterials, Ministry of Education of China (Grant No. 2006-1)

摘　　要：The behavior of a single polyethylene polymer in aqueous solution confined between two hydrophilic walls is studied with molecular dynamics (MD) simulations. The thickness of the nano-slit ranges from 1.26 to 3.15 nm, which is comparative to the polymer dimension. A monotonic transition from 3D- to 2D-like configurations is observed as the distance between the two walls narrows. Monomers are compressed into several layers and the preferred bond orientations alternate between parallel and normal to the walls accordingly. The diffusivity in the direction parallel to the wall is always larger than the one perpendicular to it. Calculation of the entropy and enthalpy changes during the folding of the polymer chain alone cannot explain the spontaneous process. The corresponding increase in water entropy due to volume expansion may be large enough to result in the overall free energy decrease.The behavior of a single polyethylene polymer in aqueous solution confined between two hydrophilic walls is studied with molecular dynamics （MD） simulations. The thickness of the nano-slit ranges from 1.26 to 3.15 nm, which is comparative to the polymer dimension. A monotonic transition from 3D- to 2D-like configurations is observed as the distance between the two walls narrows. Monomers are compressed into several layers and the preferred bond orientations alternate between parallel and normal to the walls accordingly. The diffusivity in the direction parallel to the wall is always larger than the one perpendicular to it. Calculation of the entropy and enthalpy changes during the folding of the polymer chain alone cannot explain the spontaneous process. The corresponding increase in water entropy due to volume expansion may be large enough to result in the overall free energy decrease.

关 键 词：聚乙烯聚合体 分子动力学模拟 亲水性 纳米裂缝 

分 类 号：O632.12[理学—高分子化学]