Size dependence of transfer free energies. 1. A Flory-Huggins approach
Size dependence of transfer free energies. 1. A Flory-Huggins approach
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DOI：
10.1021/j100020a076
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
Sanat K. Kumar;I. Szleifer;K. Sharp;P. Rossky;R. C. Friedman;B. Honig
中科院分区：
文献类型：
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作者：
Sanat K. Kumar;I. Szleifer;K. Sharp;P. Rossky;R. C. Friedman;B. Honig
最近有人提出，Flory-Huggins理论（FH），发现广泛使用的聚合物社区，被应用到理解之间的有机相和水的相对较短的烷烃链的分区。使用这一理论，它预测，不同物种的摩尔体积在确定溶解度中起着重要的作用，结果在一个显着增加的疏水表面张力估计从转移实验。然而，FH理论应用于烷烃溶解度的分析受到了广泛的批评。在这里，我们得出这个理论accountingspecificallyfor的压力的晶格系统，并表明，它是适当的从凝聚的聚合物溶剂相转移到气相或单体溶剂。因此，最近文献中出现的对FH理论对分区实验的适用性的全面批评是无效的。一个新的结果是，FH理论是有效的处理分配数据的任意形状的溶质，只要溶剂是链状的。另一方面，使用链增量方法的Monte Carlo模拟表明，即使在非热晶格系统的情况下，Flory-Huggins理论也高估了分子尺寸效应25%，这表明该理论的预测应被视为真实尺寸效应的一阶估计。讨论了Flory-Huggins理论的物理起源，并与Hildebrand的自由体积理论和Sharp等人的理论进行了联系。理想气体体积效应的求导。还考虑了溶质从气相转移到单体溶液中的摩尔体积效应的作用。
It has been recently proposed that Flory—Huggins theory (FH), which finds widespread use in the polymer community, be applied to understand the partitioning of relatively short alkane chains between an organic phase and water. Use of this theory, which predicts that the molar volumes of the different species play an important role in determining solubility, results in a significant increase in the hydrophobic surface tension estimated from transfer experiments. However, the application of FH theory to the analysis of alkane solubility has been widely criticized. Here, we derive this theory accounting specificallyfor the pressure of the lattice system, and show that it is appropriate for transfers from a condensed polymer solvent phase toeither a gas phase or a monomer solvent. The sweeping criticisms of the applicability of FH theory to partition experiments that have appeared in the recent literature are therefore not valid. A new result is that FH theory is valid for treating partition data for solutes of arbitrary shape, as long as the solvent is chain-like. On the other hand, Monte Carlo simulations using the chainincrement method indicate that Flory-Huggins theory overestimates molecular size effectsby 25% even in the case of athermal lattice systems, indicating that the predictions of this theory should be viewed as first-order estimates of true size effects. Thephysical origins of Flory-Huggins theory are discussed, and connections are made to Hildebrand’s free volume theory and also to Sharp et al.’s ideal gas derivation of volume effects. The role of molar volume effects in transfers of solutes from a gas phase to monomer solution are also considered.