Extended gibbs free energy and laplace pressure of ordered hexagonal close-packed spherical particles: A wettability study

Bayat, A ; Sharif University of Technology | 2021

163 Viewed
  1. Type of Document: Article
  2. DOI: 10.1021/acs.langmuir.1c00343
  3. Publisher: American Chemical Society , 2021
  4. Abstract:
  5. The wetting property of spherical particles in a hexagonal close-packed (HCP) ordering from extended Gibbs free energy (GFE) and Laplace pressure view points is studied. A formalism is proposed to predict the contact angle (θ) of a droplet on the HCP films and penetration angle (α) of the liquid on the spherical particles. Then, the extended Laplace pressure for the layered HCP ordering is calculated and a correlation between the wetting angle, sign of pressure, and pressure gradient is achieved. Our results show that the sign and the slope of pressure are important criteria for determining the wettability state and it is found that the contact angle is independent of the particle radius, as supported by various experimental reports. The pressure gradient for the HCP films with Young contact angle higher than (lower than) a critical contact angle, 135° (45°), is positive (negative), indicating the superhydrophobicity (superhydrophilicity) state of the surface. To validate the proposed formulation, theoretical calculations are compared with the reported experimental measurements, showing a good agreement. ©
  6. Keywords:
  7. Free energy ; Gibbs free energy ; Laplace transforms ; Pressure gradient ; Spheres ; Superhydrophilicity ; Superhydrophobicity ; Wetting ; Hexagonal close packed ; Laplace pressure ; Particle radii ; Spherical particle ; Theoretical calculations ; Wetting angle ; Wetting property ; Contact angle ; Calculation ; Contact angle ; Hydrophilicity ; Pressure gradient ; Wettability
  8. Source: Langmuir ; Volume 37, Issue 28 , 2021 , Pages 8382-8392 ; 07437463 (ISSN)
  9. URL: https://pubs.acs.org/doi/10.1021/acs.langmuir.1c00343