Institut de Physique de Rennes, IPR, CNRS-Université de Rennes 1, UMR CNRS 6251, 35042 Rennes, France.
J Phys Chem B. 2020 Dec 17;124(50):11501-11509. doi: 10.1021/acs.jpcb.0c09302. Epub 2020 Dec 8.
Prepeak in the structure factor of alcohols is known for a half century and was attributed to one of two mechanisms (i) self-assembly in aggregates and (ii) existence of spatial heterogeneity. Although both explnations are often argued the molecular origin is yet unclear. In this work, molecular dynamics simulation of neat alcohols and their mixtures in the presence of an apolar liquid in bulk and in confined phases is performed to unveil and to clarify the origin of the prepeak at the molecular scale. Unambiguously, we show that the existence of the prepeak is the result of the self-assembly in clusters leading to long-range correlations rather than the spatial heterogeneity. We also establish that the confinement of neat liquids at the nanoscale does not erase the clustering and the prepeak but strongly reduce the spatial heterogeneity. Regarding the binary alcohol/toluene mixtures, we highlight the possibility to erase the clustering and the spatial heterogeneity from nanoconfinement inducing the formation of a core-shell structure. By tuning the interfacial chemistry and pore size, we shed light on the possibility to control the spatial heterogeneity, the self-assembly, and the microphase separation.
醇类结构因子的预峰现象已经为人所知半个世纪了，它归因于以下两种机制之一：（i）在聚集体中自组装，以及（ii）存在空间异质性。尽管这两种解释经常被争论，但分子起源仍不清楚。在这项工作中，通过分子动力学模拟，研究了在本体相和受限相中存在非极性液体时，纯醇及其混合物的分子动力学。在分子尺度上揭示并阐明预峰的起源。我们明确地表明，预峰的存在是由于在簇中自组装导致长程相关性，而不是空间异质性。我们还确定了纳米尺度下纯液体的受限不会消除聚类和预峰，但会强烈降低空间异质性。关于二元醇/甲苯混合物，我们强调了通过诱导核壳结构的形成，可以从纳米限制中消除聚类和空间异质性的可能性。通过调整界面化学和孔径，我们探讨了控制空间异质性、自组装和微相分离的可能性。
