  Solutions of semiflexible polymers confined by repulsive planar walls are
studied by density functional theory and Molecular Dynamics simulations, to
clarify the competition between the chain alignment favored by the wall and the
depletion caused by the monomer-wall repulsion. A coarse-grained bead-spring
model with bond bending potential is studied, varying both the contour length
and the persistence length of the polymers, as well as the monomer
concentration in the solution (good solvent conditions are assumed throughout,
and solvent molecules are not included explicitly). The profiles of monomer
density and pressure tensor components near the wall are studied, and the
surface tension of the solution is obtained. While the surface tension slightly
decreases with chain length for flexible polymers, it clearly increases with
chain length for stiff polymers. Thus, at fixed density and fixed chain length
the surface tension also increases with increasing persistence length. Chain
ends always are enriched near the wall, but this effect is much larger for
stiff polymers than for flexible ones. Also the profiles of the mean square
gyration radius components near the wall and the nematic order parameter are
studied to clarify the conditions where wall-induced nematic order occurs.
