[en] An atomic force microscope was used to study the effects of polymer charge density on surface interactions between similarly charged silica surfaces. Copolymers of acrylamide and acrylic acid of three different charge densities (f(p) = 15, 40, and 70%) were used The dynamic light-scattering technique was used to obtain the characteristic size of these polymers in solution. Flocculation tests were performed to complement force-distance measurement. At 20 mM KCl and pH similar to 8.0, the low charge density copolymer (f(p) = 15%) caused a purely repulsive force profile between silica surfaces irrespective of the added polymer concentration, suggesting a strong adsorption of the copolymer on the surface. The medium (f(p) = 40%) and high (f(p) = 70%) charge density copolymers, on the other hand, provided an adhesive bridging attraction at low polymer concentrations, but a purely repulsive force at higher polymer concentrations. The range of these repulsive forces, however, was significantly smaller than that measured for the low charge density polymer. The medium and high charge densities exhibit nearly an identical behavior in controlling the intersurface forces, although the forces are different with respect to magnitude. The flocculation tests follow the same trend as that of force-distance data, where a complete, a partial, and no flocculation observed with high, medium, and low charge density polymers, respectively. In all the cases, the range of surface interactions can be correlated with the polymer chain dimension corresponding to the fast diffusion process (individual chains) obtained from dynamic light-scattering measurements. Mean-field models proposed for charged polymers can qualitatively explain both the dependency of bridging interactions on polymer charge density and the dependency of force-distance profiles on added polymer concentrations. Finally, a mean-field model was used quantitatively to account for the measured electrosteric interactions and their dependency on polymer charge density.
Research center :
Center for Education and Research on Macromolecules (CERM)
Disciplines :
Materials science & engineering Chemistry
Author, co-author :
Abraham, T.; Nanotechnology Research Institute, AIST, Tsukuba, Japan > Bionanomaterials Group
Christendat, D.; University of Alberta, Edmonton, Canada > Deptartment of Chemical and Materials Engineering
Xu, Z.; University of Alberta, Edmonton, Canada > Deptartment of Chemical and Materials Engineering
Masliyah, J.; University of Alberta, Edmonton, Canada > Deptartment of Chemical and Materials Engineering
Gohy, Jean-François; Université de Liège - ULiège > Department of Chemistry > Center for Education and Research on Macromolecules (CERM)
Jérôme, Robert ; Université de Liège - ULiège > Department of Chemistry > Center for Education and Research on Macromolecules (CERM)
Language :
English
Title :
Role of polylelectrolyte charge density in tuning colloidal forces
Publication date :
October 2004
Journal title :
AIChE Journal
ISSN :
0001-1541
eISSN :
1547-5905
Publisher :
John Wiley & Sons, Hoboken, United States - New Jersey
BELSPO - Politique scientifique fédérale [BE] F.R.S.-FNRS - Fonds de la Recherche Scientifique [BE] ESF - European Science Foundation [FR] NSERC - Natural Sciences and Engineering Research Council [CA]
Abraham, T., "Effects of Divalent Salt on, Adsorption Kinetics of a Hydrophobically Modified Polyelectrolyte at the Neutral Surface-Aqueous Solution Interface," Polymer, 43, 849 (2002).
Abraham, T., D. Christendat, K. Karan, Z. Xu, and J. Masliyah, "Asphaltene-Silica Interactions in Aqueous Solutions: Direct Force Measurements Combined with Electrokinetic Studies," Ind. Eng. Chem. Res., 41, 2170 (2002).
Abraham, T., S. Giasson, J. F. Gohy, and R. Jérôme, "Direct Measurements of Interactions between Hydrophobically Anchored Strongly Charged Polyelectrolyte Brushes," Langmuir, 16, 4246 (2000).
Abraham, T., A. Kumpulainen, Z. Xu, M. Rutland, P. M. Claesson, and J. Masliyah, "Polyelectrolyte Mediated Interaction between Similarly Charged Surfaces: Role of Divalent Counterions in Tuning the Surface Forces," Langmuir, 17, 8321 (2001).
Attia, Y. A., Flocculation in Biotechnology and Separation Systems, Elsevier, Amsterdam (1987).
Biggs, S., "Steric and Bridging Forces between Surfaces Bearing Adsorbed Polymer: An Atomic Force Microscopy Study," Langmuir, 11, 156 (1995).
Borukhov, I., D. Andelman, and H. Orland, "Effects of Polyelectrolyte Adsorption on Intercolloidal Forces," J. Phys. Chem. B., 103, 5042 (1999) [and references therein].
Cappella, B., and G. Deitler, "Force-Distance Curves by Atomic Force Microscopy," Surf. Sci. Rep., 34, 1 (1999).
Dahlgren, M. A. G., "Effects of Counterion Valency and Ionic Strength on Polyelectrolyte Adsorption," Langmuir, 10, 1580 (1994).
Dahlgren, M. A. G., A. Waltermo, E. Blomberg, P. M. Claesson, L. Sjostrom, T. Akkesson, and B. Jonsson, "Salt Effects on the Interaction between Adsorbed Cationic Polyelectrolyte Layers," J. Phys. Chem., 97, 11769 (1993).
De Gennes, P. G., "Polymers at Interfaces; A Simplified View," Adv. Colloid Interface Sci., 27, 189 (1987).
Ducker, W. A., T. J. Senden, and R. M. Pashley, "Direct Measurement of Colloidal Forces Using an Atomic Force Microscope," Nature, 353, 239 (1991).
Farinato, R. S., Y. S. Huang, and P. Hawkins, Colloid-Polymer Interactions, R. S. Farinato and P. L. Dubin, Eds., Wiley-Interscience, New York, Chapter 1, p. 3 (1999).
Fleer, G. J., M. A. Stuart, J. M. H. M. Scheutjens, T. Cosgrove, and B. Vincent, Polymers at Interface, Chapman & Hall, London (1993).
Förster, S., M. Schmidt, and M. Antonietti, "Static and Dynamic Light Scattering by Aqueous Polyelectrolyte Solutions: Effects of Molecular Weight, Charge Density and Added Salt," Polymer, 31, 781 (1990).
Israelachvili, J. N., Intermolecular and Surface Forces, 2nd Edition, Academic Press, London, Chapter 12 (1992a).
Israelachvili, J. N., Intermolecular and Surface Forces, 2nd Edition, Academic Press, London, Chapter 14 (1992b).
Joanny, J. F., and X. Chatellier, "Adsorption of Polyelctrolyte Solutions on Surfaces; A Debye-Huckel Therory," J. Phys. II Fr., 6, 1667 (1996).
Joanny, J. F., and X. Chatellier, "Adsorption of Gaussian Random Copolymer Chain at an Interface," Eur. Phys. E., 1, 9 (2000).
Kamiyama, Y., and J. Israelachvili, "Effects of pH and Salt on the Adsorption and Interactions of an Amphoteric Polyelectrolyte," Macromolecules, 25, 5081 (1992).
Kelley, T. W., P. A. Schorr, D. J. Kristin, M. Tirrell, and C. D. Frisbie, "Direct Force Measurements at Polymer Brush Surfaces by Atomic Force Microscopy," Macromolecules, 31, 4297 (1998).
Kujawa, P., J. M. Rosiak, J. Selb, and F. Candau, "Micellar Synthesis and Properties of Hydrophobically Associating Polyampholytes," Macromol. Chem. Phys., 202, 1384 (2001).
Linse, P., "Adsorption of Weakly Charged Polyelectrolytes at Oppositely Charged Surfaces," Macromolecules, 29, 326 (1996).
Lowack, K., and C. A. Helm, "Molecular Mechanisms Controlling the Self-Assembly Process of Polyelectrolyte Multilayers," Macromolecules, 31, 823 (1998).
Lyklema, J., Fundamentals of Interface and Colloid Science, Vol. II, Chapter 5, Academic Press, London (1995).
Milner, S. T., "Polymer Brushes," Science 251, 905 (1991).
Murat, M., and G. Grest, "Molecular Dynamics Simulations of the Force between a Polymer Brush and an AFM Tip," Macromolecules, 29, 8282 (1996).
Osterberg, M., J. Laine, P. Stenius, A. Kumpulainen, and P. M. Claesson, "Forces between Xylan-Coated Surfaces: Effect of Polymer Charge Density and Background Electrolyte," J. Colloid Interface Sci., 242, 59 (2001).
Overney, R. M., D. P. Leta, C. F. Pictroski, M. H. Rafailovich, Y. Liu, J. Quinn, J. Sokolov, A. Eisenberg, and G. Overney, "Compliance Measurements of Confined Polystyrene Solutions by Atomic Force Microscopy," Phys. Rev. Lett., 76, 1272 (1996).
Podgornik, R., "Electrostatlc Forces between Charged Surfaces in the Presence of a Polyelectrolyte Chain," J. Phys. Chem., 95, 5249 (1991).
Podgornik, R., "Self-Consistent-Field Theory for Confined Polyelectrolyte Chains," J. Phys. Chem., 96, 886 (1992).
Podgornik, R., T. Akesson, and B. Jonsson, "Colloidal Interactions Mediated via Polyelectrolytes," J. Chem. Phys., 102, 9423 (1995).
Provencher, S. W., "Inverse Problems in Polymer Characterization- Direct Analysis of Polydispersity with Photon Correlation Spectroscopy," Macromol. Chem., 180, 201 (1979).
Shubin, V., and P. Linse, "Self-Consistent-Field Modeling of Polyelectrolyte Adsorption on Charge-Regulating Surfaces," Macromolecules, 30, 5944 (1998).
Texter, J., and M. Tirrell, "Chemical Processing by Self-Assembly," AIChE J., 47, 1706 (2001).
Verwey, E. J. W., and J. Th. G. Overbeek, Theory of Stability of Lyophobic Colloids, Elsevier, Amsterdam (1948).
Zhulina, E. B., and O. V. Borisov, "Structure and Interaction of Weakly Charged Polyelectrolyte Brushes: Self-Consistent Field Theory," J. Chem. Phys., 107, 5952 (1997).
