Fast transient fluorescence technique (FTRT) for studying dissolution of polymer glasses

The fast transient fluorescence technique (FTRT) was used for studying the swelling and dissolution of a glassy polymer formed by free-radical polymer ization of methyl methacrylate (MMA). Anthracene (An) was introduced during polymerization as a fluorescence probe to monitor swelling and dissolution . Swelling and dissolution processes of disc-shaped poly(methyl methacrylat e) (PMMA) glasses in a chloroform-heptane mixture were monitored by measuri ng the fluorescence lifetimes of An from its decay traces. A method is deve loped for low quenching efficiencies for measuring lifetimes, tau, of An, a nd it was observed that tau values decreased as the dissolution process pro ceeded. Desorption, D, and mutual diffusion, D-m, coefficients of An molecu les were measured during dissolution of PMMA and found to be around 5.4 x 1 0(-6) (cm(2)/s) and 2.2 x 10(-5) (cm(2)/s), respectively. (C) 1999 John Wil ey & Sons, Inc.