Abstract
In a mixture of colloidal particles and polymer molecules, the particles may experience an attractive “depletion force” if the size of the polymer molecule is larger than the interparticle separation. This is because individual polymer molecules experience less conformational entropy if they stay between the particles than they escape the inter-particle space, which results in an osmotic pressure imbalance inside and outside the gap and leads to interparticle attraction. This depletion force has been the subject of several studies since the 1980s, but the direct measurement of this force is still experimentally challenging as it requires the detection of energy variations of the order of k B T and beyond. We present here our results for applying total internal reflection microscopy (TIRM) to directly measure the interaction between a free-moving particle and a flat surface in solutions consisting of small water-soluble organic molecules or polymeric surfactants. Our results indicate that stable nanobubbles (ca. 150 nm) exist free in the above aqueous solutions. More importantly, the existence of such nanobubbles induces an attraction between the spherical particle and flat surface. Using TIRM, we are able to directly measure such weak interaction with a range up to 100 nm. Furthermore, we demonstrate that by employing thermo-sensitive microgel particles as a depleting agent, we are able to quantitatively measure and reversibly control k B T-scale depletion attraction as function of solution pH.
Similar content being viewed by others
References
Tuinier, R., Rieger, J. and de Kruit, C.G., Adv. Colloid Interface Sci., 2003, 103: 1
Farinato, R.S. and Dubin, P.L., eds., “Colloid-polymer interactions: from fundamentals to practice”, Wiley-VCH, New York, 1999
Poon, W.C.K., J. Phys., Condens. Matter, 2002, 14: R859
Mutch, K.J., van Duijneveldt, J.S. and Eastoe, J., Soft Matter, 2007, 3: 155
Snir, Y. and Kamien, R.D., Science, 2005, 307: 1067
Kaplan, P.D., Rouke, J.L. and Yodh, A.G., Phys. Rev. Lett., 1994, 72: 582
Dinsmore, A.D., Yodh, A.G. and Pine, D.J., Nature, 1996, 383: 239
Lin, K.H., Crocker, J.C., Prasad, V., Schofield, A., Weitz, D.A., Lubensky, T.C. and Yodh, A.G., Phys. Rev. Lett., 2000, 85: 1770
Wilking, J.N., Graves, S.M., Chang, B.C., Meleson, K., Lin, M.Y. and Mason, T.G., Phys. Rev. Lett., 2006, 96: 015501
Dinsmore, A.D., Prasad, V., Wong, I.Y. and Weitz, D.A., Phys. Rev. Lett., 2006, 96: 185502
Mason, T.G., Phys. Rev. E, 2002, 66: 060402
Badaire, S., Cottin-Bizonne, C., Woody, J.W., Yang, A. and Stroock, A.D., J. Am. Chem. Soc., 2007, 129: 40
Dinsmore, A.D. and Yodh, A.G., Langmuir, 1999, 15: 314
Asakura, S. and Oosawa, F., J. Chem. Phys., 1954, 22: 1255
Vrij, A., Pure Appl. Chem., 1976, 48: 471
Sharma, A. and Walz, J.Y., J. Chem. Soc., Faraday Trans., 1996, 92: 4997
Richetti, P. and Kekicheff, P., Phys. Rev. Lett., 1992, 68: 1951
Sober, D.L. and Walz, J.Y., Langmuir, 1995, 11: 2352
Milling, A.J. and Kendall, K., Langmuir, 2000, 16: 5106
Piech, M. and Walz, J.Y., J. Phys. Chem. B, 2004, 108: 9177
Biggs, S., Dagastine, R.R. and Prieve, D.C., J. Phys. Chem. B, 2002, 106: 11557
Biggs, S., Prieve, D.C. and Dagastine, R.R., Langmuir, 2005, 21: 5421
Kleshchanok, D., Tuinier, R. and Lang, P.R., J. Phys.: Condens. Matter, 2008, 20: 073101
Verma, R., Crocker, J.C., Lubensky, T.C. and Yodh, A.G., Phys. Rev. Lett., 1998, 81: 4004
Crocker, J.C., Matteo, J.A., Dinsmore, A.D. and Yodh, A.G., Phys. Rev. Lett., 1999, 82: 4352
Lin, K.H., Crocker, J.C., Zeri, A.C. and Yodh, A.G., Phys. Rev. Lett., 2001, 87: 088301
Milling, A.J. and Biggs, S.J., Colloid Interface Sci., 1995, 170: 604
Knoben, W., Besseling, N.A.M. and Cohen Stuart, M.A., Phys. Rev. Lett., 2006, 97: 06830
Prieve, D.C., Adv. Colloid Interface Sci., 1999, 82: 93
Kleshchanok, D. and Lang, P.R., Langmuir, 2007, 23: 4332
Hertlein, C., Helden, L., Gambassi, A., Dietrich, S. and Bechinger, C., Nature, 2008, 451: 172
Rudhardt, D., Bechinger, C. and Leiderer, P., Phys. Rev. Lett., 1999, 81: 1330
Helden, L., Koenderink, G.H., Leiderer, P. and Bechinger, C., Langmuir, 2004, 20: 5662
Jin, F., Gong, X.J., Ye, J. and Ngai, T., Soft Matter, 2008, 4: 968
Ngai, T., Xing, X.C. and Jin, F., Langmuir, 2008, 24: 13912
Jin, F., Ye, J., Hong, L.Z., Lam, H.F. and Wu, C., J. Phys. Chem. B, 2007, 111: 2255
Xing, X.C., Li, Z.F. and Ngai, T., Macromolecules, 2009, 42: 7271
Scheutjens, J.M.H.M. and Fleer, G.J., J. Phys. Chem., 1979, 83: 1619
Scheutjens, J.M.H.M. and Fleer, G.J., J. Phys. Chem., 1980, 84: 178
Pagac, E.S., Tilton, R.D. and Prieve, D.C., Langmuir, 1998, 14: 5106
Hiemenz, P.C. and Rajagopalan, C., “Principles colloid and surface chemistry”, Marcel Dekker, New York, 1977
Bahadur, P. and Pandya, K., Langmuir, 1992, 8: 2666
Brown, W. and Schillen, K., J. Phys. Chem., 1992, 96: 6038
Author information
Authors and Affiliations
Corresponding author
Additional information
This work was financially supported by the Hong Kong Special Administration Region (HKSAR) General Research Fund (CUHK 402809, 2160387) and the Direct Grant for Research 2008/09 of the Chinese University of Hong Kong (CUHK 2060371).
Rights and permissions
About this article
Cite this article
Gong, Xj., Xing, Xc., Wei, Xl. et al. Direct measurement of weak depletion force between two surfaces. Chin J Polym Sci 29, 1–11 (2011). https://doi.org/10.1007/s10118-010-1012-8
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10118-010-1012-8