The European Physical Journal E

, Volume 22, Issue 4, pp 325–333 | Cite as

Behavior of block-polyampholytes near a charged surface

Regular Articles

Abstract.

The behavior of polyampholytes near a charged planar surface is studied by means of Monte Carlo simulations. The investigated polyampholytes are overall electrically neutral and made up of oppositely charged units (called blocks) that are highly charged and of the the same length. The influence of block length and substrate's surface-charge-density on the adsorption behavior is addressed. A detailed structural study, including local monomer concentration, monomer mean height, and transversal chain size, is provided. It is demonstrated that adsorption is favored for long enough blocks and/or high enough Coulomb interface-ion couplings. By explicitly measuring the chain size in the bulk, it is shown that the charged interface induces either a swelling or a shrinkage of the transversal dimension of the chain depending, in a non trivial manner, on the block length.

PACS.

82.35.Gh Polymers on surfaces; adhesion  82.35.Jk Copolymers, phase transitions, structure 87.15.Aa Theory and modeling; computer simulation  

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Y. Watanabe, K. Kubo, S. Sato, Langmuir 15, 4157 (1999) CrossRefGoogle Scholar
  2. M. Dreja, K. Heine, B. Tieke, G. Junkers, J. Colloid Interface Sci. 191, 131 (1997) CrossRefGoogle Scholar
  3. S. Neyret, L. Ouali, F. Candau, E. Pefferkorn, J. Colloid Interface Sci. 176, 86 (1995) CrossRefGoogle Scholar
  4. J.F. Joanny, J. Phys. II 4, 1281 (1994) CrossRefGoogle Scholar
  5. B. Mahltig, P. Müller-Buschbaum, M. Wolkenhauer, O. Wunnicke, S. Wiegand, J.F. Gohy, R. Jérôme, M. Stamm, J. Colloid Interface Sci. 242, 36 (2001) CrossRefGoogle Scholar
  6. B. Mahltig, J.F. Gohy, R. Jérôme, M. Stamm, J. Polym. Sci. B 39, 709 (2001) CrossRefGoogle Scholar
  7. E. Zhulina, A.V. Dobrynin, M. Rubinstein, Eur. Phys. J. E 5, 41 (2001) CrossRefGoogle Scholar
  8. A.V. Dobrynin, Phys. Rev. E 63, 051802 (2001) CrossRefADSGoogle Scholar
  9. A.V. Dobrynin, M. Rubinstein, J.F. Joanny, Macromolecules 30, 4332 (1997) CrossRefGoogle Scholar
  10. N.P. Shusharina, P. Linse, Eur. Phys. J. E 6, 147 (2001) CrossRefGoogle Scholar
  11. J. McNamara, C.Y. Kong, M. Muthukumar, J. Chem. Phys. 117, 5354 (2002) CrossRefADSGoogle Scholar
  12. A. Akinchina, N.P. Shusharina, P. Linse, Langmuir 20, 10351 (2004) CrossRefGoogle Scholar
  13. R. Messina, Phys. Rev. E 70, 051802 (2004); 74, 049906(E) (2006) CrossRefADSMathSciNetGoogle Scholar
  14. R. Messina, J. Chem. Phys. 124, 014705 (2006) CrossRefADSGoogle Scholar
  15. Only the monomer-monomer excluded volume interaction was not modeled by a hard-sphere potential. There, a purely repulsive Lennard-Jones potential was used Google Scholar
  16. A.G. Moreira, R.R. Netz, Europhys. Lett. 52, 705 (2000) CrossRefADSGoogle Scholar
  17. Note that in our case where we have only one chain and no contact with a bulk reservoir, so that the monomer density profile will necessarily tend to zero. This means that the density will always show a peak (although very small in practice in case of depletion) Google Scholar
  18. A. Shafir, D. Andelman, R.R. Netz, J. Chem. Phys. 119, 2355 (2003) CrossRefADSGoogle Scholar
  19. P. de Gennes, Scaling Concepts in Polymer Physics (Cornell University Press, Ithaca, New York, 1979) Google Scholar
  20. R. Varoqui, J. Phys. II 3, 1097 (1993) CrossRefGoogle Scholar
  21. I. Borukhov, D. Andelman, H. Orland, Macromolecules 31, 1665 (1998) CrossRefGoogle Scholar
  22. A. Esztermann, R. Messina, H. Löwen, Europhys. Lett. 73, 864 (2006) CrossRefADSGoogle Scholar
  23. To be more explicit, let us consider a diblock PA where the two oppositely charged blocks of length b are characterized by a linear charge density ± ξe (with ξ>0). Neglecting the block-block correlations, the minimum energy configuration Estretched in the adsorbed stretched state is given (in units of kBT) by \(E_{stretched} = \int_0^b \frac{z}{\lambda}\xi dz - \int_b^{2b} \frac{z}{\lambda}\xi dz = -\frac{\xi b^2}{\lambda}\) whereas for the “L” structure we get \(E_{{\rm L}} = -\int_0^b \frac{z}{\lambda}\xi dz = -\frac{\xi b^2}{2\lambda}\) which shows that \(\Delta E = E_{{\rm L}}- E_{stretched} = \frac{\xi b^2}{2\lambda} > 0\). In this reasoning and for the sake of simplicity, we have also ignored the presence of the counterions that ultimately should not change the sign of ΔE Google Scholar

Copyright information

© EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2007

Authors and Affiliations

  1. 1.Institut für Theoretische Physik II, Heinrich-Heine-Universität Düsseldorf, Universitätsstrasse 1DüsseldorfGermany

Personalised recommendations