Physical ageing of the contact line on colloidal particles at liquid interfaces

ABSTRACT Young’s law1 predicts that a colloidal sphere in equilibrium with a liquid interface will straddle the two fluids, its height above the interface defined by an equilibrium contact

angle2. This has been used to explain why colloids often bind to liquid interfaces3,4, and has been exploited in emulsification5, water purification6, mineral recovery7, encapsulation8 and

the making of nanostructured materials9,10. However, little is known about the dynamics of binding. Here we show that the adsorption of polystyrene microspheres to a water/oil interface is

characterized by a sudden breach and an unexpectedly slow relaxation. The relaxation appears logarithmic in time, indicating that complete equilibration may take months. Surprisingly,

viscous dissipation appears to play little role. Instead, the observed dynamics, which bear strong resemblance to ageing in glassy systems, agree well with a model describing activated

hopping of the contact line over nanoscale surface heterogeneities. These results may provide clues to longstanding questions on colloidal interactions at an interface11,12. Access through

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CONTENT BEING VIEWED BY OTHERS DIRECT MEASUREMENTS OF THE COLLOIDAL DEBYE FORCE Article Open access 29 June 2023 NONEQUILIBRIUM CONTINUOUS PHASE TRANSITION IN COLLOIDAL GELATION WITH

SHORT-RANGE ATTRACTION Article Open access 16 July 2020 A UNIFIED STATE DIAGRAM FOR THE YIELDING TRANSITION OF SOFT COLLOIDS Article 27 July 2023 REFERENCES * Young, T. An essay on the

cohesion of fluids. _Phil. Trans. R. Soc. Lond._ 95, 65–87 (1805). Article  Google Scholar  * Binks, B. Colloidal particles at liquid interfaces. _Phys. Chem. Chem. Phys._ 9, 6298–6299

(2007). Article  CAS  Google Scholar  * Ramsden, W. Separation of solids in the surface-layers of solutions and ‘suspensions’ (Observations on surface-membranes, bubbles, emulsions, and

mechanical coagulation). _Proc. R. Soc. Lond._ 72, 156–164 (1903). CAS  Google Scholar  * Pickering, S. U. Emulsions. _J. Chem. Soc._ 91, 2001–2021 (1907). Article  Google Scholar  *

Aveyard, R., Binks, B. P. & Clint, J. H. Emulsions stabilised solely by colloidal particles. _Adv. Colloid Interface Sci._ 100–102, 503–546 (2003). Article  Google Scholar  * Nguyen, A.,

Pugh, R. J. & Jameson, G. J. _Colloidal Particles at Liquid Interfaces_ (Cambridge Univ. Press, 2006). Google Scholar  * Bhargava, A., Francis, A. V. & Biswas, A. K. Interfacial

studies related to the recovery of mineral slimes in a water–hydrocarbon liquid-collector system. _J. Colloid Interface Sci._ 64, 214–227 (1978). Article  CAS  Google Scholar  * Dinsmore, A.

et al. Colloidosomes: Selectively permeable capsules composed of colloidal particles. _Science_ 298, 1006–1009 (2002). Article  CAS  Google Scholar  * Velikov, K. P. & Velev, O. D.

_Colloidal Particles at Liquid Interfaces_ (Cambridge Univ. Press, 2006). Google Scholar  * McGorty, R., Fung, J., Kaz, D. & Manoharan, V. N. Colloidal self-assembly at an interface.

_Mater. Today_ 13, 34–42 (June, 2010). Article  CAS  Google Scholar  * Park, B. J. et al. Direct measurements of the effects of salt and surfactant on interaction forces between colloidal

particles at water–oil interfaces. _Langmuir_ 24, 1686–1694 (2008). Article  CAS  Google Scholar  * Nikolaides, M. et al. Electric-field-induced capillary attraction between like-charged

particles at liquid interfaces. _Nature_ 420, 299–301 (2002). Article  CAS  Google Scholar  * Seveno, D. et al. Dynamics of wetting revisited. _Langmuir_ 25, 13034–13044 (2009). Article  CAS

  Google Scholar  * Redon, C., Brochard-Wyart, F. & Rondelez, F. Dynamics of dewetting. _Phys. Rev. Lett._ 66, 715–718 (1991). Article  CAS  Google Scholar  * Dagastine, R. R. &

White, L. R. Forces between a rigid probe particle and a liquid interface II. The general case. _J. Colloid Interface Sci._ 247, 310–320 (2002). Article  CAS  Google Scholar  * Ally, J.,

Kappl, M., Butt, H. & Amirfazli, A. Detachment force of particles from air–liquid interfaces of films and bubbles. _Langmuir_ 26, 18135–18143 (2010). Article  CAS  Google Scholar  * Lee,

S. et al. Characterizing and tracking single colloidal particles with video holographic microscopy. _Opt. Express_ 15, 18275–18282 (2007). Article  Google Scholar  * Park, B. J. &

Furst, E. M. Optical trapping forces for colloids at the oil–water interface. _Langmuir_ 24, 13383–13392 (2008). Article  CAS  Google Scholar  * Mbamala, E. & von Grunberg, H. Effective

interaction of a charged colloidal particle with an air–water interface. _J. Phys. Condens. Matter_ 14, 4881–4900 (2002). Article  CAS  Google Scholar  * Brenner, H. The slow motion of a

sphere through a viscous fluid towards a plane surface. _Chem. Eng. Sci._ 16, 242–251 (1961). Article  CAS  Google Scholar  * Paunov, V. N. Novel method for determining the three-phase

contact angle of colloid particles adsorbed at air–water and oil–water interfaces. _Langmuir_ 19, 7970–7976 (2003). Article  CAS  Google Scholar  * Hodge, I. M. Physical aging in polymer

glasses. _Science_ 267, 1945–1947 (1995). Article  CAS  Google Scholar  * De Gennes, P., Brochard-Wyart, F. & Quere, D. _Capillarity and Wetting Phenomena: Drops, Bubbles, Pearls, Waves_

(Springer, 2003). Google Scholar  * Blake, T. D. & Haynes, J. M. Kinetics of liquid/liquid displacement. _J. Colloid Interface Sci._ 30, 421–423 (1969). Article  CAS  Google Scholar  *

Rolley, E. & Guthmann, C. Dynamics and hysteresis of the contact line between liquid hydrogen and cesium substrates. _Phys. Rev. Lett._ 98, 166105 (2007). Article  CAS  Google Scholar  *

Prevost, A., Rolley, E. & Guthmann, C. Thermally activated motion of the contact line of a liquid 4He meniscus on a cesium substrate. _Phys. Rev. Lett._ 83, 348–351 (1999). Article  CAS

  Google Scholar  * Petrov, J. G., Ralston, J., Schneemilch, M. & Hayes, R. A. Dynamics of partial wetting and dewetting of an amorphous fluoropolymer by pure liquids. _Langmuir_ 19,

2795–2801 (2003). Article  CAS  Google Scholar  * Blake, T. D. The physics of moving wetting lines. _J. Colloid Interface Sci._ 299, 1–13 (2006). Article  CAS  Google Scholar  *

Brochard-Wyart, F. & de Gennes, P. G. Dynamics of partial wetting. _Adv. Colloid Interface Sci._ 39, 1–11 (1992). Article  CAS  Google Scholar  * Oettel, M. & Dietrich, S. Colloidal

interactions at fluid interfaces. _Langmuir_ 24, 1425–1441 (2008). Article  CAS  Google Scholar  * Park, B. J., Vermant, J. & Furst, E. M. Heterogeneity of the electrostatic repulsion

between colloids at the oil–water interface. _Soft Matter_ 6, 5327–5333 (2010). Article  CAS  Google Scholar  * Park, B. J. & Furst, E. M. Attractive interactions between colloids at the

oil–water interface. _Soft Matter_ 7, 7676–7682 (2011). Article  CAS  Google Scholar  * Stamou, D., Duschl, C. & Johannsmann, D. Long-range attraction between colloidal spheres at the

air–water interface: The consequence of an irregular meniscus. _Phys. Rev. E_ 62, 5263–5272 (2000). Article  CAS  Google Scholar  Download references ACKNOWLEDGEMENTS We thank S. Ghosh for

his help in the work that inspired these experiments; L. DeLorenzo for her work on sample cell prototypes; S. Rubinstein and H. Stone for critical discussions; and J. MacArthur and S. 

Cotreau for guidance in construction of the apparatus. This work was supported by the National Science Foundation under CAREER award number CBET-0747625 as well as through the Harvard MRSEC

under award number DMR-0820484. AUTHOR INFORMATION Author notes * Madhav Mani Present address: Present address: Kavli Institute for Theoretical Physics, Department of Physics, University of

California, Santa Barbara, California 93106, USA, * David M. Kaz and Ryan McGorty: These authors contributed equally to this work AUTHORS AND AFFILIATIONS * Department of Physics, Harvard

University, Cambridge, Massachusetts 02138, USA David M. Kaz, Ryan McGorty & Vinothan N. Manoharan * School of Engineering and Applied Sciences, Harvard University, Cambridge,

Massachusetts 02138, USA Madhav Mani, Michael P. Brenner & Vinothan N. Manoharan Authors * David M. Kaz View author publications You can also search for this author inPubMed Google

Scholar * Ryan McGorty View author publications You can also search for this author inPubMed Google Scholar * Madhav Mani View author publications You can also search for this author

inPubMed Google Scholar * Michael P. Brenner View author publications You can also search for this author inPubMed Google Scholar * Vinothan N. Manoharan View author publications You can

also search for this author inPubMed Google Scholar CONTRIBUTIONS R.M. and D.M.K. designed the experimental apparatus, analysed the data and interpreted the results. M.M. led the development

of the model and assisted with interpretation of the data. M.P.B. advised on the model and manuscript. V.N.M. directed the experiments and their interpretation. All authors collaborated on

the manuscript. CORRESPONDING AUTHORS Correspondence to Madhav Mani or Vinothan N. Manoharan. ETHICS DECLARATIONS COMPETING INTERESTS The authors declare no competing financial interests.

SUPPLEMENTARY INFORMATION SUPPLEMENTARY INFORMATION Supplementary Information (PDF 616 kb) RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Kaz, D.,

McGorty, R., Mani, M. _et al._ Physical ageing of the contact line on colloidal particles at liquid interfaces. _Nature Mater_ 11, 138–142 (2012). https://doi.org/10.1038/nmat3190 Download

citation * Received: 07 June 2011 * Accepted: 31 October 2011 * Published: 04 December 2011 * Issue Date: February 2012 * DOI: https://doi.org/10.1038/nmat3190 SHARE THIS ARTICLE Anyone you

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