The time-resolved, fast transient fluorescence technique, which uses a stro
be master system, was employed for studying the swelling of a disc-shaped p
oly(methyl methacrylate) gel. The disc-shaped gel was prepared by free-radi
cal copolymerization of methyl methacrylate and ethylene glycol dimethacryl
ate. Pyrene (Py) was introduced as a fluorescence probe during polymerizati
on. After this gel was dried, swelling and slow-release experiments were pe
rformed in chloroform at room temperature. Lifetimes of Py were measured du
ring in situ swelling and slow-release experiments. An equation was derived
for low-quenching efficiencies to interpret the behavior of lifetimes in a
nd out of the gel during swelling. Py lifetimes in the gel decreased as swe
lling proceeded, but Py lifetimes out of the gel stayed constant during the
slow-release experiments. The Li-Tanaka equation was used to determine the
cooperative and mutual diffusion coefficients, which were around 10(-5) an
d 10(-7) cm(2)s(-1), respectively. (C) 2000 John Wiley & Sons, Inc.