Gao Lichao, McCarthy Thomas J
Polymer Science and Engineering Department, University of Massachusetts, Amherst, Massachusetts 01003, USA.
Langmuir. 2007 Mar 27;23(7):3762-5. doi: 10.1021/la062634a. Epub 2007 Feb 22.
We argue using experimental data that contact lines and not contact areas are important in determining wettability. Three types of two-component surfaces were prepared that contain "spots" in a surrounding field: a hydrophilic spot in a hydrophobic field, a rough spot in a smooth field, and a smooth spot in a rough field. Water contact angles were measured within the spots and with the spot confined to within the contact line of the sessile drop. Spot diameter and contact line diameter were varied. All of the data indicate that contact angle behavior (advancing, receding, and hysteresis) is determined by interactions of the liquid and the solid at the three-phase contact line alone and that the interfacial area within the contact perimeter is irrelevant. The point is made that Wenzel's and Cassie's equations are valid only to the extent that the structure of the contact area reflects the ground state energies of contact lines and the transition states between them.
我们利用实验数据表明，在决定润湿性方面，接触线而非接触面积起着重要作用。制备了三种双组分表面，它们在周围区域包含“斑点”：疏水区域中的亲水斑点、光滑区域中的粗糙斑点以及粗糙区域中的光滑斑点。在斑点内部以及斑点被限制在 sessile 液滴的接触线范围内时测量了水接触角。改变了斑点直径和接触线直径。所有数据表明，接触角行为（前进角、后退角和滞后角）仅由三相接触线上液体与固体的相互作用决定，而接触周边内的界面面积无关紧要。需要指出的是，Wenzel 方程和 Cassie 方程仅在接触面积的结构反映接触线的基态能量及其之间的过渡态的程度上有效。
