Molecular dynamics simulations are carried out to investigate the structure of a single poly(oxyethylene) (POE) chain in aqueous and methanolic solutions in a strong external electric field. The conformational changes of the polymer chain induced by the strong external electric field are monitored by measuring the radius of gyration, the components of the gyration tensor, the end-to-end distance, dihedral angle distribution, and the helical content. The isotropic coil size measures, i.e., the radius of gyration and the end-to-end distance mostly decrease with growing intensity of the electric field except a small increase occurring between 0 and 1 V/nm in water. Therefore, in most cases the field compresses the polymer coil. Nevertheless, the deformation is anisotropic, leading to an average spheroid which is prolate in water (again with the exception of fields less or equal to 1 V/nm) and oblate in methanol. Analysis of dihedrals suggests that POE chain’s partially helical structure is promoted at electric fields above 1 V/nm. Changes caused by the strong external electric field in the solvent–solvent and solvent–polymer hydrogen-bonding structure are monitored by measuring the number of hydrogen bonds, their strength, and the volume of the bonding region. Results show non-trivial, solvent-specific effects, which are yet to be fully understood.

中文翻译：

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强电场对显式溶剂中聚氧乙烯链结构影响的分子动力学模拟研究


进行分子动力学模拟以研究在强外部电场中水溶液和甲醇溶液中单个聚氧乙烯 （POE） 链的结构。通过测量回转半径、回转张量的分量、端到端距离、二面角分布和螺旋含量来监测由强外部电场引起的聚合物链的构象变化。各向同性线圈尺寸测量，即回转半径和端到端距离大多随着电场强度的增加而减小，除了在水中 0 到 1 V/nm 之间发生小幅增加。因此，在大多数情况下，磁场会压缩聚合物线圈。然而，变形是各向异性的，导致平均球体在水中呈长圆形（同样，小于或等于 1 V/nm 的场除外）在甲醇中呈扁圆形。二面体分析表明，POE 链的部分螺旋结构在高于 1 V/nm 的电场下得到促进。通过测量氢键的数量、强度和键合区域的体积，可以监测溶剂-溶剂和溶剂-聚合物氢键结构中强外部电场引起的变化。结果显示了非平凡的溶剂特异性影响，但尚未完全了解。