The effect of temperature on contact angles and wetting transitions for n -alkanes on PTFE
| Autor: | Ramon L. Cerro, M. Elena Diaz, M. D. Savage |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Chemistry
Hamaker constant Intermolecular force Thermodynamics Nanotechnology 02 engineering and technology Atmospheric temperature range 021001 nanoscience & nanotechnology Surfaces Coatings and Films Electronic Optical and Magnetic Materials Biomaterials Contact angle symbols.namesake Colloid and Surface Chemistry 020401 chemical engineering Wetting transition symbols Wetting 0204 chemical engineering van der Waals force 0210 nano-technology Volatility (chemistry) |
| Zdroj: | Journal of Colloid and Interface Science. 503:159-167 |
| ISSN: | 0021-9797 |
| DOI: | 10.1016/j.jcis.2017.05.003 |
| Popis: | The aim of this paper is to present a method for predicting the effect of temperature on contact angles and wetting transitions for n-alkanes on PTFE. The analysis is based on the effect of temperature on two closely related phenomena, which are critical in the determination of contact angles: intermolecular forces and the thickness of an adsorbed film in the region adjacent to the three-phase contact. Considering solely van der Waals forces, it is possible to reproduce the experimental temperature dependence of contact angles. At low temperature values, contact angles show a small and linear decrease with temperature. For higher temperature values, substantially larger decreases are exhibited by the more volatile alkanes. In the case of n-octane, a single transition from partial to total wetting is found at 443K. This transition, which arises from the vanishing of the effective Hamaker constant at 430K, is characterized by a surface specific heat exponent close to one, indicating the existence of a first order wetting transition. For the less volatile alkanes, the contact angle decrease is progressively less pronounced as the volatility decreases in such a way that for n-hexadecane the contact angle remains approximately constant throughout the temperature range under study. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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