UV-visible (UVV) technique is used for monitoring of polymer film dissolution. These films are formed from pyrene (P)-labeled poly(methyl methacrylate) (PMMA) latex particles, sterically stabilized by poly isobutylene (PIB, Annealing of films was performed above T-g at various temperatures for 30-min time intervals. Diffusion of solvent molecules (chloroform) into the annealed latex film was followed by desorption of PMMA chains. Desorption of P-labeled PMMA chains was monitored in real time by the absorbance change of P in the polymer-solvent mixture. A diffusion model with a moving boundary was used to quantify real time UW data. Diffusion coefficients of desorbed PMMA chains were measured and found to be between 2 and 0.6 x 10(-11) cm(2) s(-1) in the 100 and 275 degrees C temperature range. (C) 2000 John Wiley & Sons, Inc.