Solvent dynamics in swollen polymers

We report molecular dynamics simulations of benzene-polystyrene systems (0–84.2 wt.%). The composition dependence of calculated solvent diffusion coefficients shows good agreement with experiment and it also follows well the predictions by lattice models. The mobility of solvent molecules in the first solvation shell of the polymer is the same as that in the bulk. The reorientation of benzene molecules in the gel is non-exponential and anisotropic, the reorientation of the ring normal being slower than the in-plane reorientation. This anisotropy increases from 100 for neat benzene to 103 at the highest polymer concentration.