Sosso Gabriele C, Sudera Prerna, Backes Anna T, Whale Thomas F, Fröhlich-Nowoisky Janine, Bonn Mischa, Michaelides Angelos, Backus Ellen H G
Department of Chemistry, University of Warwick Gibbet Hill Road Coventry CV4 7AL UK
Max Planck Institute for Polymer Research Ackermannweg 10 55128 Mainz Germany.
Chem Sci. 2022 Apr 8;13(17):5014-5026. doi: 10.1039/d1sc06338c. eCollection 2022 May 4.
The freezing of water into ice is a key process that is still not fully understood. It generally requires an impurity of some description to initiate the heterogeneous nucleation of the ice crystals. The molecular structure, as well as the extent of structural order within the impurity in question, both play an essential role in determining its effectiveness. However, disentangling these two contributions is a challenge for both experiments and simulations. In this work, we have systematically investigated the ice-nucleating ability of the very same compound, cholesterol, from the crystalline (and thus ordered) form to disordered self-assembled monolayers. Leveraging a combination of experiments and simulations, we identify a "sweet spot" in terms of the surface coverage of the monolayers, whereby cholesterol maximises its ability to nucleate ice (which remains inferior to that of crystalline cholesterol) by enhancing the structural order of the interfacial water molecules. These findings have practical implications for the rational design of synthetic ice-nucleating agents.
水结冰成冰是一个尚未被完全理解的关键过程。一般来说，它需要某种形式的杂质来引发冰晶的异相成核。分子结构以及相关杂质内部的结构有序程度，在决定其有效性方面都起着至关重要的作用。然而，区分这两种作用对实验和模拟来说都是一项挑战。在这项工作中，我们系统地研究了同一种化合物胆固醇从晶体（因而有序）形式到无序自组装单分子层的冰核形成能力。利用实验和模拟相结合的方法，我们在单分子层的表面覆盖率方面确定了一个“最佳点”，通过增强界面水分子的结构有序性，胆固醇在这个点上使其冰核形成能力最大化（尽管仍低于晶体胆固醇）。这些发现对合成冰核剂的合理设计具有实际意义。
