Rother Gernot, Woywod Dirk, Schoen Martin, Findenegg Gerhard H
Stranski-Laboratorium für Physikalische und Theoretische Chemie, Fakultät für Mathematik und Naturwissenschaften, Technische Universität Berlin, Strasse des 17. Juni 112, D-10623 Berlin, Germany.
J Chem Phys. 2004 Jun 22;120(24):11864-73. doi: 10.1063/1.1755667.
The preferential adsorption of one component of a binary system at the inner surfaces of mesoporous silica glasses was studied in a wide composition range at temperatures close to liquid/liquid phase separation. Confinement effects on the adsorption were investigated by using three controlled-pore glass (CPG-10) materials of different mean pore size (10 to 50 nm). For the experimental system (2-butoxyethanol+water), which exhibits an upper miscibility gap, strong preferential adsorption of water occurs, as the coexistence curve is approached at bulk compositions, at which water is the minority component. In this strong adsorption regime the area-related surface excess amount of adsorbed water decreases with decreasing pore width, while the shift in the volume-related mean composition of the pore liquid shows an opposite trend, i.e., greatest deviation from bulk composition occurring in the most narrow pores. A simple mean-field lattice model of a liquid mixture confined by parallel walls is adopted to rationalize these experimental findings. This model reproduces the main findings of the confinement effect on the adsorption near liquid/liquid phase separation.
在接近液/液相分离的温度下，研究了二元体系中一种组分在介孔二氧化硅玻璃内表面的优先吸附情况，研究范围涵盖了较宽的组成范围。通过使用三种平均孔径不同（10至50纳米）的可控孔径玻璃（CPG - 10）材料，研究了限制作用对吸附的影响。对于呈现上临界混溶间隙的实验体系（2 - 丁氧基乙醇 + 水），当在本体组成接近共存曲线时，水作为少数组分，会发生强烈的水优先吸附现象。在这种强吸附状态下，与面积相关的吸附水表面过量量随孔径减小而降低，而与体积相关的孔内液体平均组成的偏移则呈现相反趋势，即在最窄的孔中与本体组成的偏差最大。采用一个由平行壁限制的液体混合物的简单平均场晶格模型来解释这些实验结果。该模型再现了在液/液相分离附近限制作用对吸附影响的主要结果。
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