  Strong coupling phenomena, such as the like charged macroions attraction,
opposite charged macroions repulsion, charge renormalization or charge
inversion, are known to be mediated by multivalent counterions. Most theories
treat the counterions as point charges, and describe the system by a single
coupling parameter that measures the strength of the Coulomb interactions. In
many biological systems, the counterions are highly charged and have finite
sizes and can be well-described by polyelectrolytes. The shapes and
orientations of these polymer counterions play a major role in the
thermodynamics of these systems. In this work we apply a field theoretic
description in the strong coupling regime to polyelectrolytes. We work out the
special cases of rod-like polymer counterions confined by one and two charged
walls respectively. The effects of the geometry of the rod-like counterions and
the excluded volume of the walls on the density, pressure and the free energy
of the rodlike counterions are discussed.
