Reordering of disc-shaped polystyrene (PS) gels due to multiple swelling, under organic vapor was studied by using Fast Transient Fluorescence (FTRF) technique. Disc-shaped polystyrene gels were prepared by free radical copolymerization (FRC) of styrene (S) with ethylene glycol dimethacrylate (EGDM) as a crosslinker. Pyrene (P) was introduced as a fluorescence probe during polymerization. Swelling experiments were performed by using P doped PS gels under chloroform vapor. After each swelling step, gels were left to dry in an oven at 30 °C for consecutive reswelling experiments. Decay curves of P were measured and pyrene lifetimes, τ, were determined. It was observed that τ values decreased as swelling recycles were repeated. It was observed that after the fifth swelling step, two different regimes appeared in the swelling processes in PS gels. Swelling time constant, τ c, and cooperative diffusion coefficients, D c, were determined by using Li–Tanaka equation for each swelling step in both regimes. It was observed that D c values decreased up to tenth swelling step and then remained unchanged in both regimes.