Soft Matter Physics Laboratory, School of Advanced Materials Science and Engineering, SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 16419, Korea.
Sci Rep. 2017 Feb 16;7:42848. doi: 10.1038/srep42848.
When a drop is placed on a flat substrate tilted at an inclined angle, it can be deformed by gravity and its initial contact angle divides into front and rear contact angles by inclination. Here we study on evaporation dynamics of a pure water droplet on a flat solid substrate by controlling substrate inclination and measuring mass and volume changes of an evaporating droplet with time. We find that complete evaporation time of an inclined droplet becomes longer as gravitational influence by inclination becomes stronger. The gravity itself does not change the evaporation dynamics directly, whereas the gravity-induced droplet deformation increases the difference between front and rear angles, which quickens the onset of depinning and consequently reduces the contact radius. This result makes the evaporation rate of an inclined droplet to be slow. This finding would be important to improve understanding on evaporation dynamics of inclined droplets.
当液滴放置在倾斜的平面基底上时，它会受到重力的影响而变形，其初始接触角会因倾斜而分为前接触角和后接触角。在这里，我们通过控制基底倾斜度并随时间测量蒸发液滴的质量和体积变化，研究了纯水滴在平面固体基底上的蒸发动力学。我们发现，随着倾斜度引起的重力影响增强，倾斜液滴的完全蒸发时间会变长。重力本身并不会直接改变蒸发动力学，但是重力引起的液滴变形会增加前后角度之间的差异，从而加速脱附的发生，从而减小接触半径。这一结果使得倾斜液滴的蒸发速率变慢。这一发现对于提高对倾斜液滴蒸发动力学的理解非常重要。
