...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>The journal of physical chemistry, B. Condensed matter, materials, surfaces, interfaces & biophysical >Concentration Dependence of Water Dynamics in Poly(Ethylene Oxide)/Water Solutions from Molecular Dynamics Simulations
【24h】

Concentration Dependence of Water Dynamics in Poly(Ethylene Oxide)/Water Solutions from Molecular Dynamics Simulations

机译：分子动力学模拟中聚环氧乙烷/水溶液中水动力学的浓度依赖性

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

We have performed molecular dynamics simulations of aqueous solutions of poly(ethylene oxide) (PEO) in order to investigate the influence of the polymer on water dynamics. Simulations were performed on 12 repeat unit CH_3-capped PEO chains (530 Da) at 318 K covering a composition range (polymer weight fraction) from 0.17 to 1.0. The simulations employed an ab initio quantum-chemistry-based PEO/water and PEO/PEO force field together with the TIP4P (four-point transferable intermolecular potential) water model. Water translational and rotational diffusion were found to slow monotonically, whereas water-water and water-ether hydrogen bond lifetimes increased with increasing polymer concentration. The slowing of water dynamics in PEO/water solutions was associated with PEO-water interactions that are moderated in concentrated solutions by the formation of water clusters. Water translational motion could be ascribed to a combination of free water (water not involved with PEO hydration) that exhibited bulklike water dynamics and bound (hydrating water) whose motion was strongly correlated with that of the PEO molecule. Water rotational motion was found to be strongly correlated with translation motion and exhibited increasing anisotropy with increasing PEO concentration indicative of preferred rotation of the water molecules around their dipole moment vector. At high PEO concentration, water and ether oxygen atoms exhibited well pronounced subdiffusive behavior occurring on a picosecond time scale that disappears upon dilution. The characteristic length scale for the water subdiffusive behavior associated with water caging correlates well with nearest-neighbor ether oxygen-ether oxygen distance.
机译：为了研究聚合物对水动力学的影响，我们进行了聚环氧乙烷（PEO）水溶液的分子动力学模拟。在318 K上对12个重复单元的CH_3封端的PEO链（530 Da）进行了模拟，覆盖了0.17至1.0的组成范围（聚合物重量分数）。模拟使用了从头算起基于量子化学的PEO /水和PEO / PEO力场以及TIP4P（四点可转移分子间电势）水模型。发现水的平移和旋转扩散单调减慢，而水-水和水-醚氢键的寿命随着聚合物浓度的增加而增加。 PEO /水溶液中水动力学的减慢与PEO-水的相互作用有关，而PEO与水的相互作用在浓溶液中通过形成水团而得以缓和。水的平移运动可归因于游离水（不参与PEO水化的水）的组合，该水表现出块状水动力学，并且结合（水化的水）运动与PEO分子的运动密切相关。发现水旋转运动与平移运动密切相关，并且随着PEO浓度的增加而表现出各向异性的增加，表明水分子围绕其偶极矩矢量的优选旋转。在高PEO浓度下，水和醚氧原子在皮秒级的时间尺度上表现出明显的亚扩散行为，稀释后消失。与水笼养有关的水亚扩散行为的特征长度尺度与最近邻醚氧-醚氧距离密切相关。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号