Abstract
We present the results of molecular dynamics simulations of polyelectrolyte
solutions in near--solvent conditions for polymer backbone. Polyelectrolyte
solutions are modeled as an ensemble of bead-spring chains of charged
Lennard-Jones particles with explicit counterions. Simulations were
performed for both fully and partially charged polyelectrolyte chains
with the number of monomers N varying from 25 to 300 in the range
of polymer concentrations covering both dilute and semidilute regime.
Polyelectrolyte chains in dilute solutions are nonuniformly stretched
with the projection of the linear monomer density onto the end-to-end
vector increasing logarithmically from the middle of the chain. The
simulation results for chain size dependence on the degree of polymerization
at different polymer concentrations are in good qualitative agreement
with predictions of the modified scaling model that takes into account
nonuniform stretching of polyelectrolyte chains. In semidilute solutions
we confirm that the correlation length is inversely proportional
to the square root of polymer concentration. By measuring the bond
angle correlation function, we have determined that polyelectrolyte
chains can be viewed as flexible chains with the persistence length
proportional to the correlation length. Our results for the concentration
dependence of chain size Re on polymer concentration for the longest
chains (N = 187 and N = 300) are approaching the power law c-1/4,
predicted by the scaling model of salt-free polyelectrolyte solutions.
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