Wetting and Drying of Colloidal Droplets: Physics and Pattern Formation

Abstract

When a colloidal droplet is deposited on a solid substrate at ambient condition, it will experience the processes of wetting and drying spontaneously. These ostensibly simple and ubiquitous processes involve numerous physics: droplet spreading and wetting, three-phase contact line motion, flow fields inside droplets, and mass transportation within droplets during drying. Meanwhile, the continuous evaporation of liquid produces inter-and/or intra-molecular interactions among suspended materials and builds up the internal stress within droplets. After drying, interesting and complex desiccation patterns form in the dried droplets. These desiccation patterns are believed to have wide applications, e.g., medical diagnosis. However, many potential applications are limited by the current understanding of wetting and drying of colloidal droplets. This chapter focuses on the complex physics associated with these processes and the pattern formation in the dried colloidal droplets. Moreover, potential applications of these desiccation patterns and prospective works of wetting and drying of the colloidal droplets are outlined in this chapter.

Pattern formation in drying blood drops

“…One such complication is the redistribution of components that occurs in the early stages of drying, which is responsible for the ring-like profiles that develop in most circumstances [20]. This process has been studied extensively in recent years, evidenced by the quantity of recent books and reviews on the topic [18,[21][22][23][24][25][26][27][28][29][30].…”

Photonic Thin Films Assembled from Amphiphilic Cellulose Nanofibrils Displaying Iridescent Full-Colors

“…For a liquid droplet on a surface, the height (h) is associated with the radius R and CA (θ): h = R tan(θ/2). 51 The radius for both aq. CNF and graphene/CNF remained unchanged at 1 (normalized) for ∼25 min, then drastically reduced (Figure 5c), which is obviously different from the constant decreasing radius of pure water.…”

Potential application of the Hogarth curves in the modern garment

“…On the other hand, it is well known that curves are rich in the expression for the fashion design, while the potential application of the Hogarth curves proposed in this work is just the tip of the iceberg. We believe that our works in the Hogarth curves would be widely extended to other research and industrial fields, e.g., architectural arts, soft decoration, environmental arts, ceramics and natural science in the coming future (Zhu et al , 2016; Chen et al , 2016; Zhu et al , 2018; Chen et al , 2019). More future works are therefore necessary for advancing the potential applications of the beautiful lines, e.g., Hogarth curves.…”