Internal wettability investigation of mesoporous silica materials by ellipsometric porosimetry
Internal wettability investigation of mesoporous silica materials by ellipsometric porosimetry
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DOI：
10.1016/j.tsf.2023.139683
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发表时间：
2023-01-22
期刊：
影响因子：
2.1
通讯作者：
Basa, Peter
中科院分区：
文献类型：
--
作者：
Furedi, Mate;Fodor, Balint;Basa, Peter
二氧化硅基介孔薄膜由于具有高比表面积、孔隙率可控、合成简单、可剪裁等独特性能，被广泛应用于增透涂层、生物、化学传感器件等先进功能材料的制备。对其孔隙结构的准确了解是至关重要的，这突出了对准确表征工具的需求。从这个意义上讲，椭圆偏振测孔法代表了一个强大而通用的表征平台，提供了关于各种介孔薄膜的总孔隙率、孔径大小、孔径分散性、力学性能(杨氏模数)和表面积的可靠信息。尽管通过开尔文方程模拟毛细凝聚的基本框架已经建立，但一个描述符，介孔结构的内部润湿性对于可靠的材料表征仍然是一个具有挑战性的变量。通过传统的液滴形状方法无法观察到纳米尺度上的润湿，而用宏观性质来近似内部润湿可能是不准确的，因为这两种润湿行为并不一定相互关联。在这里，我们提出了一种基于真空椭圆偏振测孔仪的方法来测定功能化介孔二氧化硅薄膜的内接触角。通过甲基官能化调节已知介孔结构的表面能，使我们能够将不同吸附材料(水、甲醇、甲苯、环己烷)的孔填充差异与它们的内部接触角联系起来。我们的研究对广泛适用于有机吸附剂和介孔吸附材料的广义内接触角的测定具有指导意义。
Silica-based mesoporous films have been widely applied in the fabrication of advanced functional materials, such as anti-reflective coatings, bio-, and chemical sensing devices, due to their unique properties, e.g., high surface area, controlled porosity, and the ease and tailorability of their synthesis. Precise knowledge of their pore architecture is crucial, highlighting the need for accurate characterization tools. In this sense, ellipsometric porosimetry represents a powerful and versatile characterization platform, providing access to reliable information about total porosity, pore size, pore size dispersity, mechanical properties (Young's modulus) and surface area of a great variety of mesoporous thin films.While the underlying framework of modeling capillary condensation via the Kelvin equation is well established, one descriptor, the internal wettability of mesoporous architectures remains a challenging variable for reliable material characterization. Wetting on the nanoscale cannot be observed via the traditional drop -shape method, while approximating internal wetting by the macroscopic property can be inaccurate as the two wetting behaviors do not necessarily correlate. Herein, we present a method based on vacuum ellipsometric porosimetry for the determination of the internal contact angle of functionalized mesoporous silica thin films. Tuning of the surface energy for a known mesoporous architecture by methyl-functionalization enabled us to relate differences in the pore filling for various ad-sorptives (water, methanol, toluene, cyclohexane) to their internal contact angles. Our study serves as a guide for generalized internal contact angle determination suitable for a wide range of organic adsorptives and mesoporous sorbent materials.