Tay A, Monteux C, Bendejacq D, Lequeux F
PPMD-SIMM, UMR, CNRS, UPMC, ESPCIParisTech, Paris, France.
Eur Phys J E Soft Matter. 2010 Nov;33(3):203-10. doi: 10.1140/epje/i2010-10662-7. Epub 2010 Oct 24.
The wettability of coatings is very sensitive to the amount of solvent they may contain. When a droplet of volatile solvent, such as water, is deposited on a substrate, its vapor may quickly condensate just ahead of the contact line. We give an estimation of the extent of solvent uptake by a coating of variable thickness e , in front of an advancing contact line of given velocity U . Depending on the values of e and U , we observe three regimes: at low velocity and for a thin coating, the coating adsorbs a fraction of solvent that can quickly equilibrate across its entire thickness, so that it mainly appears solvophilic, while this is not the case for a thick coating. For high velocities, regardless the coating thickness, the coating ahead of the contact line does not have enough time to adsorb a significant amount of solvent, so that it mainly appears solvophobic. All these phenomena appear to be controlled by a molecular cut-off length.
涂层的润湿性对其可能含有的溶剂量非常敏感。当一滴挥发性溶剂（如水）沉积在基材上时，其蒸汽可能会在接触线前方迅速凝结。我们给出了在给定速度U的前进接触线前，厚度可变的涂层e对溶剂吸收程度的估计。根据e和U的值，我们观察到三种情况：在低速和薄涂层情况下，涂层吸收的一部分溶剂可以在其整个厚度上迅速达到平衡，因此它主要表现为亲溶剂性，而厚涂层则不然。对于高速情况，无论涂层厚度如何，接触线前方的涂层没有足够的时间吸附大量溶剂，因此它主要表现为疏溶剂性。所有这些现象似乎都受分子截止长度的控制。
