Fast transient fluorescence technique for monitoring swelling of poly(methyl methacrylate) gels

A fast transient fluorescence technique (FTRF) which uses the Strobe Master System (SMS), is introduced for studying swelling of a cylindrical poly(me thyl methacrylate) (PMMA) gel. PMMA gel was prepared by free radical copoly merization of methyl (methacrylate) (MMA) and ethylene glycol dimethacrylat e (EGDM). Pyrene (P-y) was introduced as a fluorescence probe during polyme rization and lifetimes of P-y were measured during in situ swelling process . Chloroform was used as a swelling agent. An equation is derived for low q uenching efficiencies to interpret the behavior of mean lifetimes [tau] dur ing swelling. It was observed that [tau] values decreased as swelling proce eded. The Li-Tanaka equation was used to determine the cooperative, D-c and mutual D-m diffusion coefficients, which were found to be around 10(-5) an d 10(-7) cm(2) ns(-1), respectively. (C) 2000 Elsevier Science Ltd. All rig hts reserved.