Theory and simulation of the swelling of polymer gels

A combined discontinuous molecular dynamics and Monte Carlo simulation tech nique is used to study the swelling of athermal, continuous-space, near-per fect, trifunctional polymer networks containing hard chains of lengths 20 a nd 35 immersed in an athermal hard-sphere solvent. The swelling simulations are conducted under conditions of constant pressure and chemical potential . A simple, analytical theory for gel swelling is presented in which the ge l free energy is calculated as the sum of an elastic, affine-type term, and a liquidlike mixing term that is based on the generalized-Flory dimer equa tion of state. The theory shows good agreement with our simulation results for the gel properties at swelling equilibrium. (C) 2000 American Institute of Physics. [S0021-9606(00)50425-5].