Swelling of polyelectrolyte networks

Employing molecular dynamics simulations of a coarse-grained model, the equilibrium swelling behavior of a cross-linked polyelectrolyte gel has been investigated with a bead-spring defect-free network with diamond-like topology under good solvent conditions and close to the theta-point, the counterions were treated explicitly. To examine the validity range of simple scaling arguments we varied the amount of charges in the system, the length of the network chains, the strength of the electrostatic interactions for both solvent qualities over a wide range of parameters. We find that classical theories only apply in the limit of weak electrostatics and suggest corrections based on the microscopic interplay of the systems' components accessible in a simulation, which model successfully our measured data.