Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia; Jožef Stefan International Postgraduate School, Jamova 39, SI-1000 Ljubljana, Slovenia.
Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia.
J Colloid Interface Sci. 2022 Feb 15;608(Pt 2):1718-1727. doi: 10.1016/j.jcis.2021.10.066. Epub 2021 Oct 17.
Contact-line motion upon drying of a sessile droplet strongly affects the solute transport and solvent evaporation profile. Hence, it should have a strong impact on the deposit formation and might be responsible for volcano-like, dome-like and flat deposit morphologies.
A method based on a thin-film interference was used to track the drop height profile and contact line motion during the drying. A diverse set of drying scenarios was obtained by using inks with different solvent compositions and by adjusting the substrate wetting properties. The experimental data was compared to the predictions of a phenomenological model.
We highlight the essential role of contact-line mobility on the deposit morphology of solution-based inks. A pinned contact line produces exclusively ring-like deposits under normal conditions. On the contrary, drops with a mobile contact line can produce ring-, flat- or dome-like morphology. The developed phenomenological model shows that the deposit morphology depends on solvent evaporation profile, evolution of the drop radius relative to its contact angle, and the ratio between initial and maximal (gelling) solute concentration. These parameters can be adjusted by the ink solvent composition and substrate wetting behaviour, which provides a way for deposition of uniform and flat deposits via inkjet printing.
液滴在干燥过程中的接触线运动强烈影响溶质传输和溶剂蒸发轮廓。因此，它应该对沉积物的形成有强烈的影响，并且可能是火山状、圆顶状和平坦状沉积物形态的原因。
我们使用基于薄膜干涉的方法来跟踪液滴在干燥过程中的高度轮廓和接触线运动。通过使用具有不同溶剂组成的油墨和调整基底润湿性来获得不同的干燥情况。将实验数据与唯象模型的预测进行了比较。
我们强调了接触线迁移率对基于溶液油墨的沉积物形态的重要作用。在正常条件下，固定接触线只会产生环状沉积物。相反，具有移动接触线的液滴可以产生环状、平坦状或圆顶状形态。所开发的唯象模型表明，沉积物形态取决于溶剂蒸发轮廓、液滴半径相对于接触角的演变以及初始和最大（胶凝）溶质浓度之间的比值。这些参数可以通过油墨溶剂组成和基底润湿性进行调整，这为通过喷墨印刷沉积均匀和平坦的沉积物提供了一种方法。
