Fast transient fluorescence method for measuring swelling and drying activation energies of a polystyrene gel

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, τ 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 τ values decreased as swelling is proceeded. Li–Tanaka equation was used to determine the swelling time constant, τc and cooperative diffusion coefficients, Dc for the swelling processes. It is observed that lifetimes, τ 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, ΔE were measured for the swelling and drying processes and found to be 80.0 and 33.5 kJ mol−1, respectively.