Nanofluids have gained more importance in the different process industries because of the enhanced wettability, thermal properties, and nature to form a specific self-assembly pattern. This study shows the wettability nature of three commercial surfaces by ZnO nanofluids with and without synthetic anionic sodium dodecyl sulfate (SDS) surfactant. The wettability nature of a particular solid surface is influenced by the chemical nature as well as the size and concentration of nanomaterial in nanofluids. The ZnO nanofluids do not affect the wetting property of the base fluid because of the hydrophilic nature of the ZnO nanoparticles which prefers the particle to stay in the bulk for better stability. Though additionally in the presence of anionic surfactant in ZnO nanofluids, it is showing the synergetic effect and effectively increases the wettability properties of the base ZnO nanofluids. The rheological properties of the ZnO nanofluids are also affected in surfactant media, it deviates from the Newtonian to slightly non-Newtonian behavior in the presence of synthetic anionic SDS surfactant. But most importantly, the presence of the surfactant molecules influences the effective forces which directly suppress the uniform particles deposition toward the specific coffee ring pattern. This study will give a clear idea about the reason behind the formation of the coffee ring pattern of the ZnO nanoparticles from the evaporating droplet. The result of this study concludes that the application of the nanofluids can be enhanced in oil recovery or as drilling fluid in the presence of surfactant because of the effective decrease in viscosity.

中文翻译：

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在阴离子表面活性剂存在下，界面和流变学特性在抑制氧化锌纳米流体均匀沉积到咖啡环图案中的重要性

由于增强的润湿性、热性能和形成特定自组装模式的性质，纳米流体在不同的加工工业中变得越来越重要。该研究显示了含和不含合成阴离子十二烷基硫酸钠 (SDS) 表面活性剂的 ZnO 纳米流体对三种商业表面的润湿性。特定固体表面的润湿性受化学性质以及纳米流体中纳米材料的大小和浓度的影响。ZnO 纳米流体不会影响基液的润湿性，因为 ZnO 纳米粒子的亲水性更喜欢粒子留在本体中以获得更好的稳定性。尽管另外在 ZnO 纳米流体中存在阴离子表面活性剂，它显示出协同效应并有效地提高了基础 ZnO 纳米流体的润湿性。ZnO 纳米流体的流变特性在表面活性剂介质中也受到影响，在合成阴离子 SDS 表面活性剂存在下，它从牛顿行为到轻微的非牛顿行为。但最重要的是，表面活性剂分子的存在会影响有效力，直接抑制向特定咖啡环图案的均匀颗粒沉积。这项研究将清楚地了解从蒸发液滴中形成 ZnO 纳米颗粒的咖啡环图案背后的原因。