Department of Genetics and Bioengineering, Yeditepe University, Ataşehir, Istanbul, Turkey.
J Colloid Interface Sci. 2011 Aug 1;360(1):8-14. doi: 10.1016/j.jcis.2011.04.007. Epub 2011 Apr 16.
The manipulation of colloidal nanoparticles (NPs) in a drying droplet has critical importance not only for several industrial applications but also their assembly into patterns on surfaces. The influence of a tip with hydrophilic or hydrophobic surfaces dipped into a drying droplet on hydrophilic or hydrophobic surfaces on the behavior of 98 nm latex NPs was investigated. The formation of concentric rings on hydrophilic glass surfaces regardless of the surface chemistry of the dipped tip was observed. On the other hand, no pattern formation on hydrophobic surfaces was observed with the insertion of the tip. With a hydrophilic tip, the concentric rings were formed due to stick-slip motion of the solvent contact line resulting from competition between pinning and capillary forces while the capillary effect was not effective until the surface of the tip was changed by adherent NPs making the tip surface available for water adherence with a hydrophobic tip, which results in the pulling of droplet towards the tip. It is also found that the tip thickness and suspension concentration significantly influences the formation of concentric rings on surfaces. This simple procedure can be used to influence the distribution or assembly of NPs in the droplet area.
在干燥液滴中操纵胶体纳米颗粒（NPs）不仅对许多工业应用具有重要意义，而且对其在表面上组装成图案也具有重要意义。研究了亲水或疏水表面的尖端浸入亲水或疏水表面的干燥液滴中对 98nm 乳胶 NPs 行为的影响。无论尖端的表面化学性质如何，在亲水玻璃表面上都观察到同心环的形成。另一方面，在插入尖端时，在疏水表面上没有观察到图案形成。对于亲水尖端，由于钉扎和毛细力之间的竞争导致溶剂接触线的粘滑运动，形成同心环，而在尖端表面被附着的 NPs 改变从而使尖端表面可用于水附着之前，毛细作用无效用疏水尖端，这导致液滴向尖端移动。还发现，尖端厚度和悬浮液浓度显著影响表面上同心环的形成。这种简单的方法可用于影响液滴区域中 NPs 的分布或组装。
