The interplay between screening properties and colloid anisotropy: towards a reliable pair potential for disc-like charged particles
arXiv:cond-mat/0407521 · doi:10.1140/epje/i2004-10052-x
Abstract
The electrostatic potential of a highly charged disc (clay platelet) in an electrolyte is investigated in detail. The corresponding non-linear Poisson-Boltzmann (PB) equation is solved numerically, and we show that the far-field behaviour (relevant for colloidal interactions in dilute suspensions) is exactly that obtained within linearized PB theory, with the surface boundary condition of a uniform potential. The latter linear problem is solved by a new semi-analytical procedure and both the potential amplitude (quantified by an effective charge) and potential anisotropy coincide closely within PB and linearized PB, provided the disc bare charge is high enough. This anisotropy remains at all scales; it is encoded in a function that may vary over several orders of magnitude depending on the azimuthal angle under which the disc is seen. The results allow to construct a pair potential for discs interaction, that is strongly orientation dependent.
13 pages, 19 figures
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- Free Isotropic-Nematic Interfaces in Fluids of Charged Platelike Colloids
- Screening of charged spheroidal colloidal particles
- Electrostatic Interactions between Janus Particles
- Evolution of nematic and ferromagnetic ordering in suspensions of magnetic nanoplatelets
- Interplay of anisotropy in shape and interactions in charged platelet suspensions
- Surface properties of fluids of charged platelike colloids
- Colloidal ionic complexes on periodic substrates: ground state configurations and pattern switching
- Screened Coulomb interactions of general macroions with nonzero particle volume
- Integral-equation analysis of transient diffusion-limited currents at disk electrodes: Asymptotic expansion and compact approximation