Dugyala Venkateshwar Rao, Basavaraj Madivala G
Polymer Engineering and Colloid Science Lab (PECS Lab), Department of Chemical Engineering, Indian Institute of Technology-Madras , Chennai 600 036, India.
Langmuir. 2014 Jul 29;30(29):8680-6. doi: 10.1021/la500803h. Epub 2014 Jul 18.
A control over the nature of deposit pattern obtained after the evaporation of solvent from a sessile drop containing dispersed materials has been demonstrated to have applications in materials engineering, separation technology, printing technology, manufacture of printed circuit boards, biology, and agriculture. In this article, we report an experimental investigation of the effect of particle shape and DLVO (Derjaguin-Landau-Verwey-Overbeek) interactions on evaporation-driven pattern formation in sessile drops. The use of a model system containing monodisperse particles where particle aspect ratio and surface charge can be adjusted reveals that a control over the nature of deposit pattern can be achieved by tuning the particle-particle and particle-substrate interactions. A clear coffee-ring formation is observed when the strength of particle-particle repulsion is higher than the particle-substrate attraction. However, complete suppression of ringlike deposits leading to a uniform film is achieved when particle-substrate and particle-particle interactions are attractive. Results illustrate that for the system of submicron ellipsoids that are hydrophilic, the nature of deposit patterns obtained after evaporation depends on the nature of interactions and not on particle shape.
已证明，控制含有分散材料的固着液滴中溶剂蒸发后获得的沉积图案的性质，在材料工程、分离技术、印刷技术、印刷电路板制造、生物学和农业等领域具有应用价值。在本文中，我们报告了一项关于颗粒形状和DLVO（德亚金-朗道-韦弗-奥弗贝克）相互作用对固着液滴中蒸发驱动图案形成影响的实验研究。使用一个包含单分散颗粒的模型系统，其中颗粒的纵横比和表面电荷可以调节，结果表明，通过调整颗粒-颗粒和颗粒-基底相互作用，可以实现对沉积图案性质的控制。当颗粒-颗粒排斥力强度高于颗粒-基底吸引力时，会观察到明显的咖啡环形成。然而，当颗粒-基底和颗粒-颗粒相互作用具有吸引力时，可实现对环状沉积物的完全抑制，从而形成均匀的薄膜。结果表明，对于亲水性亚微米椭球体系统，蒸发后获得的沉积图案的性质取决于相互作用的性质，而不是颗粒形状。
