Chaltin François, Rosenthal Martin, Léonard Alexandre F, Goderis Bart, Gommes Cedric J
Department of Chemical Engineering, University of Liège, B6A, Allée du Six Août 13, 4000 Liège, Belgium.
Dual-Belgian-Beamline (DUBBLE, BM26), European Synchrotron Radiation Facility, 71 Avenue des Martyrs, CS40220, Grenoble 38043, Cedex 9, France.
Langmuir. 2024 Oct 1;40(39):20604-20615. doi: 10.1021/acs.langmuir.4c02414. Epub 2024 Sep 20.
Numerous applications of nanoporous materials require their pores to be filled with liquids. In spite of its huge technological importance, the conditions for the wetting of nanometer-sized pores and its phenomenology are still poorly understood. We report on capillary rise experiments with water in carbon xerogels, with synchrotron small-angle scattering used to follow the process in situ at the nanometer scale. The data reveal a two-step wetting process whereby water permeates first into molecular-sized micropores, which is followed by the imbibition of larger mesopores. A Cassie-Baxter analysis shows that the presence of water in the micropores is central, as it turns the mesopores from being hydrophobic to hydrophilic. Based on the so-calculated contact angles, the mesopore wetting kinetics are found to be quantitatively described by a classical Washburn model. Modeling of the experimental water profile ahead of the Washburn front reveals strong surface barriers opposing water transfer from the mesopores to the micropores.
纳米多孔材料的众多应用都要求其孔隙被液体填充。尽管其具有巨大的技术重要性，但纳米级孔隙的润湿条件及其现象学仍未得到充分理解。我们报告了碳干凝胶中用水进行的毛细上升实验，利用同步加速器小角散射在纳米尺度原位跟踪该过程。数据揭示了一个两步润湿过程，即水首先渗透到分子尺寸的微孔中，随后大的中孔被吸液。卡西 - 巴克斯特分析表明，微孔中水的存在至关重要，因为它使中孔从疏水变为亲水。基于如此计算出的接触角，发现中孔润湿动力学可用经典的沃什伯恩模型进行定量描述。对沃什伯恩前沿之前的实验水分布进行建模显示，存在强大的表面屏障阻碍水从中孔转移到微孔。
