Molecular dynamics simulations of the hydration of poly(vinyl methyl ether):Hydrogen bonds and quasi-hydrogen bonds

被引:0
作者
WU RongLiang
机构
基金
中国国家自然科学基金;
关键词
poly(vinyl methyl ether)(PVME); molecular dynamics; computer simulation; hydrogen bond; quasi-hydrogen bond;
D O I
暂无
中图分类号
O631.3 [高聚物的化学性质];
学科分类号
070305 ; 080501 ; 081704 ;
摘要
Atomistic detailed hydration structures of poly(vinyl methyl ether)(PVME) have been investigated by molecular dynamics simulations under 300 K at various concentrations. Both radial distribution functions and the distance distributions between donors and acceptors in hydrogen bonds show that the hydrogen bonds between the polymer and water are shorter by 0.005 nm than those between water molecules. The Quasi-hydrogen bonds take only 7.2% of the van der Waals interaction pairs. It was found the hydrogen bonds are not evenly distributed along the polymer chain,and there still exists a significant amount(10%) of ether oxygen atoms that are not hydrogen bonded to water at a concentration as low as 3.3%. This shows that in polymer solutions close contacts occur not only between polymer chains but also between chain segments within the polymer,which leads to inefficient contacts between ether oxygen atoms and water molecules. Variation of the quasi-hydrogen bonds with the concentration is similar to that of hydrogen bonds,but the ratio of the repeat units forming quasi-hydrogen bonds to those forming hydrogen bonds approaches 0.2. A transition was found in the demixing enthalpy at around 30% measured by dynamic testing differential scanning calorimetry(DTDSC) for aqueous solutions of a mono-dispersed low molecular weight PVME,which can be related to the transition of the fractions of hydrogen bonds and quasi-hydrogen bonds at ~27%. The transition of the fractions of hydrogen bonds and quasi-hydrogen bonds at ~27% can be used to explain the demixing enthalpy transition at 30% at a molecular scale. In addition,at the concentration of 86%,each ether oxygen atom bonded with water is assigned 1.56 water molecules on average,and ’free’ water molecules emerge at the concentration of around 54%.
引用
收藏
页码:736 / 742
页数:7
相关论文
共 6 条
  • [1] GROMACS: Fast, flexible, and free[J] . DavidVan Der Spoel,ErikLindahl,BerkHess,GerritGroenhof,Alan E.Mark,Herman J. C.Berendsen.J. Comput. Chem. . 2005 (16)
  • [2] Flexible TIP4P model for molecular dynamics simulation of liquid water[J] . C.P. Lawrence,J.L. Skinner.Chemical Physics Letters . 2003 (5)
  • [3] Environment-sensitive hydrogels for drug delivery
    Qiu, Y
    Park, K
    [J]. ADVANCED DRUG DELIVERY REVIEWS, 2001, 53 (03) : 321 - 339
  • [4] Molecular complex formation in the system poly(vinyl methyl ether)/water
    Meeussen, F
    Bauwens, Y
    Moerkerke, R
    Nies, E
    Berghmans, H
    [J]. POLYMER, 2000, 41 (10) : 3737 - 3743
  • [5] Multilayer hydrogels as muscle-like actuators
    Liu, ZS
    Calvert, P
    [J]. ADVANCED MATERIALS, 2000, 12 (04) : 288 - 291
  • [6] A MOLECULAR-DYNAMICS METHOD FOR SIMULATIONS IN THE CANONICAL ENSEMBLE
    NOSE, S
    [J]. MOLECULAR PHYSICS, 1984, 52 (02) : 255 - 268