二元拮抗混合物的特殊液滴潤濕行為：從弱到強的液體間親和性

Abstract

當部分潤濕液體與完全潤濕液體混合時，所得的拮抗混合物會展現出特殊的潤濕行為。本研究使用MDPD模擬，探討兩種液體間的親和力如何影響奈米液滴的潤濕性，同時保持固-液間作用力不變。混合物的潤濕行為受到其組成比例(φₚ)和兩種液體之間的Flory-Huggins參數(χpt)的影響。在接觸角對φₚ的相圖中可以識別出三種不同的潤濕狀態。通過改變χpt，在部分潤濕狀態下的相圖圖形可以被分類為三組親和性類型——弱、中等和強，分別表現為“向上凹”、“向下凹”、以及“向下凹且具有最大值”的曲線。每種類型的親和性各自展現出其獨有的特徵，透過分析界面張力隨組成的變化的趨勢來理解，並進一步評估了擴展係數(S)，發現當S < 0時，模擬中直接測量到的接觸角與Young方程式的預測值在所有親和性類型中均會出現差異。因此對於奈米尺度的拮抗混合物而言，當S > 0時，僅能表示前驅膜的存在，而Young方程通常不適用。

When a partial wetting liquid is mixed with a total wetting liquid, the resulting antagonistic mixture exhibits distinctive wetting behavior. Many-body dissipative particle dynamics is used to explore how the affinity between the two liquids influences their wetting properties, while keeping solid-liquid interactions fixed. The wetting behavior of the mixture is influenced by its composition (φₚ) and the Flory-Huggins parameter between the two liquids (χpt). Three distinct wetting states can be identified in the phase diagram (contact angle vs. φₚ). By varying χpt, the phase diagram can be categorized into three affinity types—weak, intermediate, and strong—each represented by ‘concave-up’, ‘concave-down’, and ‘concave-down with a maximum’ curves, respectively. Each affinity type exhibits unique characteristics, which can be understood by analyzing the variation in interfacial tensions with composition. The spreading coefficient (S) is then evaluated, and it is found that in regions where S < 0 across all affinity types, discrepancies in the contact angle are observed between the direct measurements obtained from simulations and the predictions from Young’s equation. Therefore, S > 0 indicates the existence of a precursor film, and Young’s equation is generally invalid for describing antagonistic mixtures.