Wetting dynamics of nanoliter water droplets in nanoporous media
| Autor: | Viola I. Birss, Christopher R. Clarkson, Marwa Atwa, Chris Debuhr, Amin Ghanizadeh, Bin Pan |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Materials science
Capillary condensation Nanoporous 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences Surfaces Coatings and Films Electronic Optical and Magnetic Materials Biomaterials Contact angle Colloid and Surface Chemistry Chemical engineering Imbibition Wetting 0210 nano-technology Porous medium Environmental scanning electron microscope Nanoscopic scale |
| Zdroj: | Journal of Colloid and Interface Science. 589:411-423 |
| ISSN: | 0021-9797 |
| Popis: | Hypothesis The Lucas-Washburn (L-W) equation is the classical theory to describe the dynamics of spontaneous imbibition in single micro-channels and micro-scale porous media. However, for nanoliter droplets imbibition in nanoporous media, the L-W equation may not be suitable, due to the nanoscale liquid-solid interactions, e.g., contact line pinning and capillary condensation. In addition, for an intrinsically hydrophobic nanoporous substrate, spontaneous imbibition of a nanoliter droplet is hypothesized to occur if capillary condensation had occurred internally already. Experiments A nanoporous carbon scaffold was synthesized and used as a model nanoporous medium. A recently-developed micro-injection technique was used to generate a series of nanoliter water droplets (2.8–34 nL); the entire wetting dynamics (i.e., apparent contact angle and droplet volume as a function of time) were observed inside an environmental scanning electron microscope. Findings The L-W equation does not describe the wetting dynamics of nanoliter water droplets in nanoporous media. A new theoretical model is developed to characterize the corresponding dynamics. It is demonstrated that, even for an intrinsically hydrophobic nanoporous substrate, spontaneous imbibition of a nanoliter droplet can occur if capillary condensation had occurred internally already. |
| Databáze: | OpenAIRE |
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