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Student Number 972210006
Author Sio-kit Ng(dг)
Author's Email Address No Public.
Statistics This thesis had been viewed 824 times. Download 268 times.
Department Graduate Institute of Biophysics
Year 2009
Semester 2
Degree Master
Type of Document Master's Thesis
Language English
Title Effective electrostatic interactions between 2-D colloid particles: a modeling approach
Date of Defense 2010-07-02
Page Count 39
Keyword
  • colloid
  • counter-ion
  • like-charge attraction
  • macro-ion
  • the DLVO theory
  • the Monte Carlo simulation
  • thermal fluctuation
  • Abstract Interaction among charged colloidal particles has been investigated for long. One remarkable success, the so-called DLVO theory, considered the effects of both the van der Waals attraction and the screened Coulomb repulsion. In our current work, both the attractive and repulsive parts of the effective potential energy are observed while we consider the electrostatic effect only. In our model, we investigate the regime where the electrostatic interaction dominates and the counter-ions condense or fluctuate nearby each macro-ion. We use Monte Carlo simulations to obtain the average electrostatic interactions versus the distance between two macro-ions embedded in 2-dimensions.
    When the number of counter-ions is small, we obtain a short-range attraction and long-range repulsion. However, the attraction tends to vanish when the number of counter-ions increases. We provide possible scenarios for the sources of the attraction and repulsion.
    Table of Content Contents
    1 Introduction  1
    2 Background  3
    2.1 What are colloids?  3
    2.2 Interactions in a colloidal system  4
    2.2.1 The Debye-Hückel theory  5
    2.2.2 The van der Waals  6
    2.2.3 Like-charge attraction  7
    3 Model and Algorithm  11
    3.1 Our Basic model  11
    3.2 Simulation scheme  13
    3.2.1 The Monte Carlo methods in statistical physics  13
    3.2.2 Definition of dimensionless variables  14
    4 Results and discussions  15
    4.1 Average electrostatic interactions  15
    4.2 Asymmetric distribution of counterions  18
    4.3 The effect of confined geometry  20
    4.4 The effect of dipole-dipole interaction  22
    4.5 A Locked-up model and multipole effects  24
    4.6 Physical implementation  31
    5 Further results and analysis  34
    6 Conclusion  38
    Reference [1] Debye P W and H¨uckel E 1923 Phys. Z. 24 185
    [2] Derjaguin B V and Landau L 1941 Acta Physicochimica (USSR) 14
    [3] Verwey E J W and Overbeek J T G 1948 Theory of the Stability of Lyophobic Colloids (Amsterdam:Elsevier)
    [4]Y. Levin, Rep. Prog. Phys. 65 (2002) 1577
    [5] G. M. Kepler and S. Fraden, Phys. Rev. Lett. 73, 356 (1994)
    [6] Y. Han and D. G. Grier, Phys. Rev. Lett. 91, 038302 (2003)
    [7] W. Chen et al., Phys. Rev. Lett. 95, 218301 (2005)
    [8] W. Chen et al., Phys. Rev. E 74, 021406 (2006)
    [9] T. Liu, J. Am. Chem. Soc. 2003, 125, 312.
    [10]G. Liu, J. Am. Chem. Soc. 2004, 126, 16690
    [11]A. E. Larsen and D. G. Grier, Nature (London) 385, 230 (1997)
    [12] D. G. Angelescu and P. Linse Langmuir 2003, 19, 9661-9668
    Advisor
  • Chi-lun Lee()
  • Files
  • 972210006.pdf
  • approve immediately
    Date of Submission 2010-08-10

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