The time-resolved, fast transient fluorescence (TRF) technique which uses a strobe master system (SMS), was employed for studying swelling and drying of disc-shaped polystyrene gels. Disc-shaped gels were prepared by free-radical crosslinking copolymerization of styrene and ethylene glycol dimethacrylate. Pyrene was introduced as a fluorescence probe during polymerization and lifetimes, tau of pyrene were measured during in situ swelling and drying processes. Chloroform was used as an organic vapor agent to induce gel swelling at various temperatures. It was observed that tau values decreased as swelling is proceeded. Li-Tanaka equation was used to determine the swelling time constant, tau(c) and cooperative diffusion coefficients, D-c for the swelling processes. It is observed that lifetimes, tau of pyrene increased during drying process and an empirical equation was introduced to determine the desorption coefficient, D for drying at various temperatures. The activation energies, DeltaE were measured for the swelling and drying processes and found to be 80.0 and 33.5 kJ mol(-1), respectively. (C) 2004 Elsevier Ltd. All rights reserved.