Pyrene lifetimes for monitoring polymer dissolution: a fast transient fluorescence study

Fast transient fluorescence technique (FTRT) was used to measure pyrene (4) Lifetimes during dissolution of glassy polymer, which is formed by free ra dical polymerization of methyl methacrylate (MMA), and Py was introduced du ring polymerization as a fluorescence probe to monitor swelling and dissolu tion. The dissolution process of poly(methyl methacrylate) (PMMA) glass was performed in chloroform (80%)-heptane (20%) mixture. Fluorescence lifetime s of Py from its decay traces were used to monitor the dissolution process. A model was derived for low quenching efficiencies for measuring mean life times, [tau], of Py and it was observed that [tau] values decreased as the dissolution process proceeded. Desorption, D and mutual diffusion, D-m coef ficients of Py molecules were measured during dissolution of PMMA and found to be around 1.19 x 10(-6) and 1.23 x 10(-6) cm(2) s(-1), respectively. (C ) 1999 Elsevier Science Ltd. All rights reserved.