ABSTRACT
Electrostatic interactions between macroions in aqueous solution
are omnipresent and therefore of fundamental interest for soft
matter, colloid science, and biomolecular systems [10]. Macroions
can appear in a multitude of forms such as surfactant micelles, poly-
electrolytes (including DNA), gels, block copolymers, nanoparticles,
extended solid surfaces (mica, clay, glass), lipid membranes, and
proteins. Their charged moieties can be fixed or mobile, polarizable,
or regulated through a dissociation process. What makes the
interaction between macroions interesting from a basic physical
point of view is the presence of small mobile ions in the aqueous solution. These ions often dissociate and become mobile because
the high dielectric constant of water, W ≈ 80, greatly reduces cation-anion attraction, thus favoring the entropic gain that comes
with the dissociation process. The relation between electrostatic
and thermal energy is often expressed in terms of the Bjerrum
length lB = e2/(4π0WkBT ), at which twomonovalent ions have an interaction energy of kBT . Here, kB is Boltzmann’s constant, T is the absolute temperature, 0 is the permittivity in vacuum, and e is the elementary charge.
