Hendrikse Rachel L, Amador Carlos, Wilson Mark R
Department of Chemistry, Durham University, Durham, DH1 3LE, UK.
Procter and Gamble, Newcastle Innovation Centre, Whitley Road, Newcastle upon Tyne, NE12 9BZ, UK.
Soft Matter. 2024 Sep 25;20(37):7521-7534. doi: 10.1039/d4sm00873a.
We investigate the effects of polarisable water models in dissipative particle dynamics (DPD) simulations, focussing on the influence these models have on the aggregation behaviour of sodium dodecyl sulfate solutions. Studies in the literature commonly report that DPD approaches underpredict the micellar aggregation number of ionic surfactants compared to experimental values. One of the proposed reasons for this discrepancy is that existing water models are insufficient to accurately model micellar solutions, as they fail to account for structural changes in water close to micellar surfaces. We show that polarisable DPD water models lead to more realistic counterion behaviour in micellar solutions, including the degree of counterion disassociation. These water models can also accurately reproduce changes in the dielectric constant of surfactant solutions as a function of concentration. We find evidence that polarisable water leads to the formation of more stable micelles at higher aggregation numbers. However, we also show that the choice of water model is not responsible for the underestimated aggregation numbers observed in DPD simulations. This finding addresses a key question in the literature surrounding the importance of water models in DPD simulations of ionic micellar solutions.
我们研究了可极化水模型在耗散粒子动力学（DPD）模拟中的作用，重点关注这些模型对十二烷基硫酸钠溶液聚集行为的影响。文献研究通常表明，与实验值相比，DPD方法对离子表面活性剂的胶束聚集数预测偏低。造成这种差异的一个原因是，现有的水模型不足以准确模拟胶束溶液，因为它们未能考虑胶束表面附近水的结构变化。我们表明，可极化的DPD水模型能使胶束溶液中的抗衡离子行为更接近实际情况，包括抗衡离子的解离程度。这些水模型还能准确再现表面活性剂溶液介电常数随浓度的变化。我们发现有证据表明，可极化水会在较高聚集数时形成更稳定的胶束。然而，我们也表明，水模型的选择并非导致DPD模拟中聚集数被低估的原因。这一发现解决了文献中围绕水模型在离子胶束溶液DPD模拟中的重要性的一个关键问题。
