González F R, Pérez-Parajón J
Instituto de Química-Física Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain.
J Chromatogr A. 2003 Mar 14;989(2):265-76. doi: 10.1016/s0021-9673(03)00085-2.
Effects of solvent density on the solubility of polar probes which undergo specific interactions with poly(oxyethylene) are studied. The analysis of retention data on capillary columns coated with oligomeric poly(oxyethylene) stationary phases shows that, within the experimental error, the enthalpic contribution to the solubility is practically independent of variations in the solvent density. Average values of enthalpies of solute transfer are reported for different probes and temperatures. The observed systematic decrease of solubility with the increasing density is due to a change of entropy. Some thermodynamic consequences inferred from these general results are discussed. One relevant observation is that the influence of solvent's final groups must be negligible. This is even the case for oligomers with number-average degrees of polymerization as low as 13, hosting solutes capable of strong interactions with the end hydroxyl groups of linear poly(ethylene glycols). Possible explanations for this behavior are explored through molecular dynamics simulations of the liquid solvent.
研究了溶剂密度对与聚（氧乙烯）发生特定相互作用的极性探针溶解度的影响。对涂覆有低聚聚（氧乙烯）固定相的毛细管柱上的保留数据进行分析表明，在实验误差范围内，溶解度的焓贡献实际上与溶剂密度的变化无关。报告了不同探针和温度下溶质转移焓的平均值。观察到溶解度随密度增加而系统地降低是由于熵的变化。讨论了从这些一般结果推断出的一些热力学后果。一个相关的观察结果是溶剂末端基团的影响必须可以忽略不计。对于数均聚合度低至13的低聚物也是如此，这些低聚物容纳能够与线性聚乙二醇的末端羟基发生强相互作用的溶质。通过液体溶剂的分子动力学模拟探索了这种行为的可能解释。
