Nandy Lucy, Fenton Julie L, Freedman Miriam Arak
Department of Chemistry, The Pennsylvania State University, Chemistry Building, University Park, Pennsylvania 16802, United States.
Department of Meteorology and Atmospheric Science, The Pennsylvania State University, Chemistry Building, University Park, Pennsylvania 16802, United States.
J Phys Chem A. 2023 Aug 3;127(30):6300-6308. doi: 10.1021/acs.jpca.3c00071. Epub 2023 Jul 20.
Heterogeneous ice nucleation activity is affected by aerosol particle composition, crystallinity, pore size, and surface area. However, these surface properties are not well understood, regarding how they act to promote ice nucleation and growth to form ice clouds. Therefore, synthesized materials for which surface properties can be tuned were examined in immersion freezing mode in this study. To establish the relationship between particle surface properties and efficiency of ice nucleation, materials, here, covalent organic frameworks (COFs), with different pore diameters and degrees of crystallinity (ordering), were characterized. Results showed that out of all the highly crystalline COFs, the sample with a pore diameter between 2 and 3 nm exhibited the most efficient ice nucleation activity. We posit that the highly crystalline structures with ordered pores have an optimal pore diameter where the ice nucleation activity is maximized and that the not highly crystalline structures with nonordered pores have more sites for ice nucleation. The results were compared and discussed in the context of other synthesized porous particle systems. Such studies give insight into how material features impact ice nucleation activity.
非均相冰核活性受气溶胶颗粒组成、结晶度、孔径和表面积的影响。然而，关于这些表面特性如何促进冰核形成和生长以形成冰云，人们尚未完全理解。因此，本研究对表面特性可调节的合成材料进行了浸入式冷冻模式的研究。为了建立颗粒表面特性与冰核效率之间的关系，对具有不同孔径和结晶度（有序度）的材料——共价有机框架（COF）进行了表征。结果表明，在所有高度结晶的COF中，孔径在2至3纳米之间的样品表现出最有效的冰核活性。我们认为，具有有序孔的高度结晶结构具有使冰核活性最大化的最佳孔径，而具有无序孔的非高度结晶结构具有更多的冰核位点。在其他合成多孔颗粒系统的背景下对结果进行了比较和讨论。此类研究有助于深入了解材料特性如何影响冰核活性。
