Electrostatic attraction between overall neutral surfaces

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Two overall neutral surfaces with positively and negatively charged domains ("patches") have been shown in recent experiments to exhibit long-range attraction when immersed in an ionic solution. Motivated by the experiments, we calculate analytically the osmotic pressure between such surfaces within the Poisson-Boltzmann framework, using a variational principle for the surface-averaged free energy. The electrostatic potential, calculated beyond the linear Debye-Hückel theory, yields an overall attraction at large intersurface separations, over a wide range of the system's controlled length scales. In particular, the attraction is stronger and occurs at smaller separations for surface patches of larger size and charge density. In this large patch limit, we find that the attraction-repulsion crossover separation is inversely proportional to the square of the patch-charge density and to the Debye screening length.

Original languageUndefined/Unknown
Article number022803
JournalPhysical Review E
Issue number2
StatePublished - 2016


FundersFunder number
Free University
Humboldt University
Technical University
Tel Aviv University Humboldt University
Alexander von Humboldt-Stiftung
United States-Israel Binational Science Foundation2012/060
Israel Science Foundation438/12

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