The effect of dynamic wetting pressure on contact angle measurements
| Autor: | Raymond Sanedrin, Abrar Ahmed, Prashant R. Waghmare, Thomas Willers |
|---|---|
| Rok vydání: | 2022 |
| Předmět: |
Work (thermodynamics)
Capillary wave Materials science Drop (liquid) 02 engineering and technology Substrate (electronics) Mechanics 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 Sessile drop technique 13. Climate action Deposition (phase transition) Wetting 0210 nano-technology |
| Zdroj: | Journal of Colloid and Interface Science. 608:1086-1093 |
| ISSN: | 0021-9797 |
| DOI: | 10.1016/j.jcis.2021.10.003 |
| Popis: | Hypothesis The drop deposition technique can impact contact angle measurements. We hypothesized that the drop pinch-off, during the traditionally used pendant drop technique, significantly alters the static contact angle. The capillary waves and dynamic wetting pressure generated during the pendant drop deposition are the source for forced spreading, which can be circumvented by alternative liquid-needle drop deposition techniques. Experiments To compare the role of drop pinch-off and resultant dynamic wetting pressure, we meticulously observed and quantified the entire drop deposition process using high speed imaging until the drop attains the static contact angle in both cases, namely pendant drop and liquid needle deposition technique. Conventionally used standard substrates are compared using both techniques and further compared using literature data. The capillary waves and corresponding drop shape variations are analysed for quantifying the dynamic wetting pressure by measuring drop base diameter, contact angle and centre of mass. Findings We compared three parameters - drop pinch-off, spreading behaviour and respective static contact angles along with the resultant dynamic wetting pressure for both the techniques, i.e., pendant drop and liquid-needle. For the pendant drop technique we observed a pronounced drop volume dependency of these parameters even though the corresponding Bond numbers are less than unity. In contrast, for the liquid needle there is no such dependency. With a theoretical argument corroborating experimental observations, this work highlights the importance of a well controlled drop deposition, with a minimum wetting pressure, in order to guarantee contact angle data that is independent of drop deposition effects, thereby only reflecting the substrate properties. |
| Databáze: | OpenAIRE |
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