Advertisement

Summary and Final Remarks

Chapter
  • 2.5k Downloads

Abstract

Many believe that the concept of wetting begins with the Young’s equation. Although the Young’s equation is very simple, it has been a source of arguments over the last two centuries because the equation comprises four quantities of which two of them cannot be measured reliably. Moreover, researchers did express frustration in their inability to measure the Young’s angle consistently, at least a century ago. This chapter provides a brief overview of the history and the source of some of the misconceptions. Fundamental concepts that have been clarified in recent years, including (1) the recognition of the fact that it is the contact line, not the contact area, that determines the contact angle; (2) advancing and receding contact angles are the most important contact angles, and they measure wettability and adhesion respectively, and surface stickiness can be predicted from the sliding angle; and (3) hydrophilicity and hydrophobicity should be defined by the receding contact angle, not the static contact angle. In answering Good’s calling for standardization of measurement protocols for contact angle measurements, a set of guidelines for determining static contact angle, advancing/receding contact angle, and sliding angle are provided. We hope that these guidelines will benefit the community in the near term and serve as a springboard for the development of standardized procedures by the “authority” or leaders in this field in the near future.

Keywords

Young’s equation Misconceptions Mechanical equilibrium Young’s angle Advancing contact angle Receding contact angle Contact angle hysteresis Ideal surface Real surface Contact line Contact area Surface characterization Measurement protocols Guidelines and best practices 

References

  1. 1.
    Young T (1805) An essay on the cohesion of fluids. Philos Trans R Soc Lond 95:65–87CrossRefGoogle Scholar
  2. 2.
    Zisman WA (1964) Relation of the equilibrium contact angle to liquid and solid constitution. In: Fowkes F (ed) Contact angle, wettability, and adhesion, advances in chemistry. American Chemical Society, Washington, DC, pp 1–51CrossRefGoogle Scholar
  3. 3.
    Dupre A (1869) Theorie Mechanique de la Chaleur. Gauthier-Villars, Pairs, p 369Google Scholar
  4. 4.
    Gibbs JW (1928) Trans Connecticut Acad Arts Sci 1876–1878, 3; “Collected Works”, vol. 1. Longmans, Green, New YorkGoogle Scholar
  5. 5.
    Rayleigh L (1890) On the tension of water surfaces, clean and contaminated, investigated by the method of ripples. Lond Edinb Dublin Philos Mag J Sci 30:386–400CrossRefGoogle Scholar
  6. 6.
    Pease DC (1945) The significance of the contact angle in relation to the solid surface. J Phys Chem 49:107–110CrossRefGoogle Scholar
  7. 7.
    Macdougall G, Ockrent C (1942) Surface energy relations in liquid/solid systems. 1. The adhesion of liquids to solids and a new method of determining the surface tension of liquids. Proc R Soc Lond A 180:151–173CrossRefGoogle Scholar
  8. 8.
    Bartell FE, Hatch GB (1934) Wetting characteristics of galena. J Phys Chem 39:11–24CrossRefGoogle Scholar
  9. 9.
    Bartell FE, Wooley AD (1933) Solid-liquid-air contact angles and their dependence upon the surface condition of the solid. J Am Chem Soc 55:3518–3527CrossRefGoogle Scholar
  10. 10.
    Johnson RE (1959) Conflicts between Gibbsian thermodynamics and recent treatments of interfacial energies in solid-liquid-vapor systems. J Phys Chem 63:1655–1658CrossRefGoogle Scholar
  11. 11.
    Cwikel D, Zhao Q, Liu C, Su X, Marmur A (2010) Comparing contact angle measurements and surface tension assessments of solid surfaces. Langmuir 26:15289–15294CrossRefGoogle Scholar
  12. 12.
    Meiron TS, Marmur A, Saguy IS (2004) Contact angle measurement on rough surfaces. J Colloid Interface Sci 274:637–644CrossRefGoogle Scholar
  13. 13.
    Della Volpe C, Maniglio D, Morra M, Siboni S (2002) The determination of a ‘stable-equilibrium’ contact angle on a heterogeneous and rough surfaces. Colloid Surf A Physicochem Eng Asp 206:47–67CrossRefGoogle Scholar
  14. 14.
    Mettu S, Chaudhury MK (2010) Stochastic relaxation of the contact line of a water droplet on a solid substrate subjected to white noise vibration: role of hysteresis. Langmuir 26:8131–8140CrossRefGoogle Scholar
  15. 15.
    Joanny JF, de Gennes PG (1984) A model for contact angle hysteresis. J Chem Phys 81:552–561CrossRefGoogle Scholar
  16. 16.
    Johnson RE, Dettre RH (1964) Contact angle hysteresis 1. Study of an idealized rough surfaces. In: Fowkes F (ed) Contact angle, wettability, and adhesion, advances in chemistry. American Chemical Society, Washington, DC, pp 112–135CrossRefGoogle Scholar
  17. 17.
    Neumann AW, Good RJ (1972) Thermodynamic of contact angles 1. Heterogeneous solid surfaces. J Colloid Interface Sci 38:341–358CrossRefGoogle Scholar
  18. 18.
    Chen YL, Helm CA, Israelachville JN (1991) Molecular mechanisms associated with adhesion and contact angle hysteresis of monolayer surfaces. J Phys Chem 95:10736–10747CrossRefGoogle Scholar
  19. 19.
    Extrand CW, Kumagai Y (1997) An experimental study of contact angle hysteresis. J Colloid Interface Sci 191:378–383CrossRefGoogle Scholar
  20. 20.
    Wenzel RN (1936) Resistance of solid surfaces to wetting by water. Ind Eng Chem 28:988–994CrossRefGoogle Scholar
  21. 21.
    Cassie ABD, Baxter S (1944) Wettability of porous surfaces. Trans Faraday Soc 40:546–551CrossRefGoogle Scholar
  22. 22.
    Forsberg PSH, Priest C, Brinkmann M, Sedev R, Ralston J (2010) Contact line pinning on microstructured surfaces for liquids in the Wenzel state. Langmuir 26:860–865CrossRefGoogle Scholar
  23. 23.
    Kanungo M, Mettu S, Law KY, Daniel S (2014) Effect of roughness geometry on wetting and dewetting of rough PDMS surfaces. Langmuir 30:7358–7368CrossRefGoogle Scholar
  24. 24.
    Choi W, Tuteja A, Mabry JM, Cohen RE, McKinley GH (2009) A modified Cassie-Baxter relationship to explain contact angle hysteresis and anisotropy on non-wetting surfaces. J Colloid Interface Sci 339:208–216CrossRefGoogle Scholar
  25. 25.
    Nosonovsky M (2007) On the range of applicability of the Wenzel and Cassie equations. Langmuir 23:9919–9920CrossRefGoogle Scholar
  26. 26.
    Samuel B, Zhao H, Law KY (2011) Study of wetting and adhesion interactions between water and various polymer and superhydrophobic surfaces. J Phys Chem C 115:14852–14861CrossRefGoogle Scholar
  27. 27.
    Roach P, Shirtcliffe NJ, Newton MI (2008) Progress in superhydrophobic surface development. Soft Matter 4:224–240CrossRefGoogle Scholar
  28. 28.
    Law KY (2014) Definitions for hydrophilicity, hydrophobicity, and superhydrophobicity: getting the basic right. J Phys Chem Lett 5:686–688CrossRefGoogle Scholar
  29. 29.
    Law KY (2015) Water interactions and definitions for hydrophilicity, hydrophobicity, and superhydrophobicity. Pure Appl Chem 87(8):759–765CrossRefGoogle Scholar
  30. 30.
    Good RJ (1977) Surface free energy of solids and liquids. Thermodynamics, molecular forces, and structures. J Colloid Interface Sci 59:398–419CrossRefGoogle Scholar
  31. 31.
    Krasovitski B, Marmur A (2005) Drops down the hill. Theoretical study of limiting contact angles and the hysteresis range on a tilted plate. Langmuir 21:3881–3885CrossRefGoogle Scholar
  32. 32.
    Pierce E, Carmona FJ, Amirfazli A (2008) Understanding of sliding and contact angle results in tilted plate experiments. Colloids Surf A Physicochem Eng Asp 323:73–82CrossRefGoogle Scholar

Copyright information

© Springer International Publishing Switzerland 2016

Authors and Affiliations

  1. 1.Founder & CEO at Research and Innovative SolutionsPenfieldUSA
  2. 2.School of Engineeing, Mechanical and Nuclear EngineeringVirginia Commonwealth UniversityRichmondUSA

Personalised recommendations