Siles Brügge Oscar, Hunter Christopher A, Leggett Graham J
Department of Chemistry, University of Sheffield, Brook Hill, Sheffield S3 7HF, U.K.
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K.
Langmuir. 2024 Jul 9;40(27):13753-13762. doi: 10.1021/acs.langmuir.3c03218. Epub 2024 Jun 27.
Lifshitz theory is widely used to calculate interfacial interaction energies and underpins established approaches to the interpretation of measurement data from experimental methods including the surface forces apparatus and the atomic force microscope. However, a significant limitation of Lifshitz theory is that it uses the bulk dielectric properties of the medium to predict the work of adhesion. Here, we demonstrate that a different approach, in which the interactions between molecules at surfaces and in the medium are described by a set of surface site interaction points (SSIPs), yields interaction free energies that are correlated better with experimentally determined values. The work of adhesion (Lifshitz) between hydrocarbon surfaces was calculated in 260 liquids using Lifshitz theory and compared with interaction free energies ΔΔ calculated using the SSIP model. The predictions of these models diverge in significant ways. In particular, ΔΔ values for hydrocarbon surfaces are typically small and vary little, but in contrast, (Lifshitz) values span 4 orders of magnitude. Moreover, the SSIP model yields significantly different ΔΔ values in some liquids for which Lifshitz theory predicts similar values of (Lifshitz). These divergent predictions were tested using atomic force microscopy. Experimentally determined works of adhesion were closer to the values predicted using the SSIP model than Lifshitz theory. In mixtures of methanol and benzyl alcohol, even greater differences were found in the interaction energies calculated using the two models: the value of ΔΔ calculated using the SSIP model declines smoothly as the benzyl alcohol concentration increases, and values are well correlated with experimental data; however, (Lifshitz) decreases to a minimum and then increases, reaching a larger value for benzyl alcohol than for methanol. We conclude that the SSIP model provides more reliable estimates of the work of adhesion than Lifshitz theory.
列夫希茨理论被广泛用于计算界面相互作用能，并为解释包括表面力仪和原子力显微镜在内的实验方法所测得的数据的既定方法提供了基础。然而，列夫希茨理论的一个显著局限性在于，它使用介质的体介电性质来预测粘附功。在此，我们证明了一种不同的方法，其中表面和介质中分子之间的相互作用由一组表面位点相互作用点（SSIPs）来描述，该方法产生的相互作用自由能与实验测定值的相关性更好。使用列夫希茨理论计算了260种液体中烃表面之间的粘附功（列夫希茨），并与使用SSIP模型计算的相互作用自由能ΔΔ进行了比较。这些模型的预测在很大程度上存在差异。特别是，烃表面的ΔΔ值通常较小且变化不大，但相比之下，（列夫希茨）值跨越了4个数量级。此外，对于列夫希茨理论预测（列夫希茨）值相似的一些液体，SSIP模型产生的ΔΔ值显著不同。使用原子力显微镜对这些不同的预测进行了测试。实验测定的粘附功更接近使用SSIP模型预测的值，而不是列夫希茨理论。在甲醇和苯甲醇的混合物中，使用这两种模型计算的相互作用能存在更大差异：使用SSIP模型计算的ΔΔ值随着苯甲醇浓度的增加而平滑下降，并且与实验数据具有良好的相关性；然而，（列夫希茨）先下降到最小值然后上升，苯甲醇的值比甲醇的值更大。我们得出结论，与列夫希茨理论相比，SSIP模型能提供更可靠的粘附功估计值。
