Fluorescence technique to study thickness effect on dissolution of latex films

In situ steady-state fluorescence (SSF) measurements were used for studying dissolution of Latex films in real time. Latex films with various thicknes ses are formed from pyrene (P) labeled poly(methyl methacrylate) (PMMA) lat ex particles, sterically stabilized by polyisobutylene (PIB). Annealing of latex films were performed above T-g at 220 degrees C temperature for 60 mi n. UV-Visible (UVV) spectrometer was used to measure the transparency of la tex films. It was observed that thicker films formed more opaque films than thinner films. Heptane (20%), chloroform (80%) mixture was used as a disso lution agent. Diffusion of pyrene labeled PMMA chains was monitored in real time by the change of pyrene fluorescence intensity, I-P in the polymer-so lvent mixture. Diffusion coefficients, D, and relaxation constants, k(0), o f PMMA chains were measured and found to be strongly dependent on the latex films thicknesses. It is observed that thicker and opaque films dissolved much faster than the thinner and transparent films. (C) 2000 John Wiley & S ons, Inc.