Surface-wetting characterization using contact-angle measurements

Abstract

Wetting, the process of water interacting with a surface, is critical in our everyday lives and in many biological and technological systems. The contact angle is the angle at the interface where water, air and solid meet, and its value is a measure of how likely the surface is to be wetted by the water. Low contact-angle values demonstrate a tendency of the water to spread and adhere to the surface, whereas high contact-angle values show the surface’s tendency to repel water. The most common method for surface-wetting characterization is sessile-drop goniometry, due to its simplicity. The method determines the contact angle from the shape of the droplet and can be applied to a wide variety of materials, from biological surfaces to polymers, metals, ceramics, minerals and so on. The apparent simplicity of the method is misleading, however, and obtaining meaningful results requires minimization of random and systematic errors. This article provides a protocol for performing reliable and reproducible measurements of the advancing contact angle (ACA) and the receding contact angle (RCA) by slowly increasing and reducing the volume of a probe drop, respectively. One pair of  ACA and RCA measurements takes ~15–20 min to complete, whereas the whole protocol with repeat measurements may take ~1–2 h. This protocol focuses on using water as a probe liquid, and advice is given on how it can be modified for the use of other probe liquids.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Fig. 1: A drop of water on an ideal solid substrate.
Fig. 2: Static water drops.
Fig. 3: Sketch of the Gibbs free energies of ideal and real wetting systems as a function of the apparent contact angle.
Fig. 4: Different stages of ACA and RCA measurement.
Fig. 5: Sketch of a goniometer setup.
Fig. 6: Recommended starting volume for RCA measurement, i.e., minimum advancing drop volume (Va) needed to reach RCA at 10 µL.
Fig. 7: Receding-contact-angle data of a nanostructured polysiloxane film on silicon substrate.
Fig. 8: Advancing contact-angle data of a nanostructured polysiloxane film on silicon substrate.
Fig. 9: Effect of advancing drop volume (Va) on the receding contact-angle measurement.
Fig. 10: Needle position for a very hydrophobic surface with low contact-angle hysteresis.

Change history

  • 07 August 2018

    The version of this Protocol originally published contained typographical errors that affected the accuracy/readability of the text. In Fig. 4e, the line “Contact angle remainsstable” should have read “Contact angle remains stable.” In Table 1, in the “Advantages” column, the second instance of “Simple” was incorrectly associated with the “Sessile-drop goniometry” method; it should have corresponded to the “Tilting plate” method. In Table 2, in the “Issues” column, the entry “Difficult to place baseline when the RCA is ~90°” was broken incorrectly in a way that might have suggested that “the RCA is ~90°” was a separate issue. These errors have been corrected in the HTML and PDF versions of the paper.

References

  1. 1.

    Riederer, M. & Schreiber, L. Protecting against water loss: analysis of the barrier properties of plant cuticles. J. Exp. Bot. 52, 2023–2032 (2001).

    CAS  Article  PubMed  Google Scholar 

  2. 2.

    Gao, X. & Jiang, L. Water-repellent legs of water striders. Nature 432, 36 (2004).

    CAS  Article  PubMed  Google Scholar 

  3. 3.

    Barthlott, W. & Neinhuis, C. Purity of the sacred lotus, or escape from contamination in biological surfaces. Planta 202, 1–8 (1997).

    CAS  Article  Google Scholar 

  4. 4.

    Parker, A. R. & Lawrence, C. R. Water capture by a desert beetle. Nature 414, 33–34 (2001).

    CAS  Article  PubMed  Google Scholar 

  5. 5.

    Zhao, G. et al. High surface energy enhances cell response to titanium substrate microstructure. J. Biomed. Mater. Res. Part A 74, 49–58 (2005).

    CAS  Article  Google Scholar 

  6. 6.

    Pankaj, S. K. et al. Applications of cold plasma technology in food packaging. Trends Food Sci. Technol. 35, 5–17 (2014).

    CAS  Article  Google Scholar 

  7. 7.

    Tian, D., Song, Y. & Jiang, L. Patterning of controllable surface wettability for printing techniques. Chem. Soc. Rev. 42, 5184–5209 (2013).

    CAS  Article  PubMed  Google Scholar 

  8. 8.

    Korhonen, J. T., Kettunen, M., Ras, R. H. A. & Ikkala, O. Hydrophobic nanocellulose aerogels as floating, sustainable, reusable, and recyclable oil absorbents. ACS Appl. Mater. Interfaces 3, 1813–1816 (2011).

    CAS  Article  PubMed  Google Scholar 

  9. 9.

    Young, T. An essay on the cohesion of fluids. Philos. Trans. R. Soc. Lond. 95, 65–87 (1805).

    Article  Google Scholar 

  10. 10.

    Extrand, C. W. & Kumagai, Y. An experimental study of contact angle hysteresis. J. Colloid Interface Sci. 191, 378–383 (1997).

    CAS  Article  PubMed  Google Scholar 

  11. 11.

    Marmur, A. Solid surface characterization by wetting. Annu. Rev. Mater. Res. 39, 473–489 (2009).

    CAS  Article  Google Scholar 

  12. 12.

    Marmur, A. A guide to the equilibrium contact angles maze in Contact Angle, Wettability and Adhesion Vol. 6 3–18 (ed. Mittal K. L.) (CRC Press, 2009).

  13. 13.

    Quéré, D. Wetting and roughness. Annu. Rev. Mater. Res. 38, 71–99 (2008).

    Article  CAS  Google Scholar 

  14. 14.

    Andrieu, C., Sykes, C. & Brochard, F. Average spreading parameter on heterogeneous surfaces. Langmuir 104, 2077–2080 (1994).

    Article  Google Scholar 

  15. 15.

    de Gennes, P. G. Wetting: statics and dynamics. Rev. Mod. Phys. 57, 827–863 (1985).

    Article  Google Scholar 

  16. 16.

    Blake, T. D. The physics of moving wetting lines. J. Colloid Interface Sci. 299, 1–13 (2006).

    CAS  Article  PubMed  Google Scholar 

  17. 17.

    Drelich, J. Guidelines to measurements of reproducible contact angles using a sessile-drop technique. Surf. Innov. 1, 248–254 (2013).

    CAS  Article  Google Scholar 

  18. 18.

    Good, R. J. Contact angle, wetting, and adhesion: a critical review. J. Adhes. Sci. Technol. 6, 1269–1302 (1992).

    CAS  Article  Google Scholar 

  19. 19.

    Kwok, D. Y. & Neumann, A. W. Contact angle measurement and contact angle interpretation. Adv. Colloid Interface Sci. 81, 167–249 (1999).

    CAS  Article  Google Scholar 

  20. 20.

    Lam, C. N. C., Lu, J. J. & Neumann, A. W. Measuring contact angle. in Handbook of Applied Surface and Colloid Chemistry (ed. K. Holmberg) Vol. 2 251–277 (2002).

    CAS  Google Scholar 

  21. 21.

    Della Volpe, C. & Siboni, S. The Wilhelmy method : a critical and practical review. Surf. Innov. 6, 120–132 (2018).

    Article  Google Scholar 

  22. 22.

    Liimatainen, V. et al. Mapping microscale wetting variations on biological and synthetic water-repellent surfaces. Nat. Commun. 8, 1798 (2017).

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  23. 23.

    Pierce, E., Carmona, F. J. & Amirfazli, A. Understanding of sliding and contact angle results in tilted plate experiments. Colloids Surf. A Physicochem. Eng. Asp. 323, 73–82 (2008).

    CAS  Article  Google Scholar 

  24. 24.

    Krasovitski, B. & Marmur, A. Drops down the hill: theoretical study of limiting contact angles and the hysteresis range on a tilted plate. Langmuir 21, 3881–3885 (2005).

    CAS  Article  Google Scholar 

  25. 25.

    Rudawska, A. & Jacniacka, E. Analysis for determining surface free energy uncertainty by the Owen-Wendt method. Int. J. Adhes. Adhes. 24, 451–457 (2009).

    Article  CAS  Google Scholar 

  26. 26.

    Zhao, Q., Liu, Y. & Abel, E. W. Effect of temperature on the surface free energy of amorphous carbon films. J. Colloid Interface Sci. 280, 174–183 (2004).

    CAS  Article  PubMed  Google Scholar 

  27. 27.

    Hoorfar, M. & Neumann, A. W. Recent progress in axisymmetric drop shape analysis (ADSA). Adv. Colloid Interface Sci. 121, 25–49 (2006).

    CAS  Article  PubMed  Google Scholar 

  28. 28.

    Tavana, H. & Neumann, A. W. On the question of rate-dependence of contact angles. Colloids Surf. A Physicochem. Eng. Asp. 282–283, 256–262 (2006).

    Article  CAS  Google Scholar 

  29. 29.

    Korhonen, J. T., Huhtamäki, T., Ikkala, O. & Ras, R. H. A. Reliable measurement of the receding contact angle. Langmuir 29, 3858–3863 (2013).

    CAS  Article  PubMed  Google Scholar 

  30. 30.

    Grundke, K. et al. Experimental studies of contact angle hysteresis phenomena on polymer surfaces - toward the understanding and control of wettability for different applications. Adv. Colloid Interface Sci. 222, 350–376 (2015).

    CAS  Article  PubMed  Google Scholar 

Download references

Acknowledgements

The protocol is the result of a procedure gradually developed since wetting research was begun in the R.H.A.R. group, and we acknowledge the contributions of H. Mertaniemi, T. Verho and M. Latikka. This work was supported by the European Research Council ERC-2016-CoG (725513-SuperRepel) and the Academy of Finland (Centres of Excellence Programme 2014–2019). X.T. is grateful for the support of the One Hundred Talents Program of SYSU and the One Thousand Youth Talents Program of China.

Author information

Affiliations

Authors

Contributions

R.H.A.R. coordinated the project. T.H., X.T. and J.T.K. performed the experiments. All authors participated in designing the protocol. T.H. and R.H.A.R. wrote the manuscript with contributions from all authors. J.T.K. wrote the Python code.

Corresponding author

Correspondence to Robin H. A. Ras.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Related links

Reliable measurement of the receding contact angle: https://doi.org/10.1021/la400009m

Guidelines to measurements of reproducible contact angles using a sessile-drop technique: https://doi.org/10.1680/si.13.00010

Characterization of super liquid-repellent surfaces: https://doi.org/10.1016/j.cocis.2014.04.009

Supplementary information

Supplementary Methods: Python code for solving the Young–Laplace equation.

The minimum advancing drop volumes (= the recommended starting volume for the receding contact-angle measurement) needed to reach RCA at 10 µL (Fig. 6), were obtained by solving the Young–Laplace equation by numerical integration, using Python programming language with Scipy library. The shape and size of the drop for different pairs of contact angle and drop volume were solved using a code that is provided in this supplementary file

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Huhtamäki, T., Tian, X., Korhonen, J.T. et al. Surface-wetting characterization using contact-angle measurements. Nat Protoc 13, 1521–1538 (2018). https://doi.org/10.1038/s41596-018-0003-z

Download citation

Further reading

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.