Packing effect on latex film formation and dissolution: a UV-visible study

Films of various thicknesses were formed from pyrene (P)-labelled poly(meth yl methacrylate) (PMMA) high T-g latex particles, sterically stabilized by poly(iso butylene) (PIB). Annealing of the films was performed above the Tg at elevated temperatures up to 270 degreesC for 30 min intervals. The UV-v isible (UVV) technique was used to monitor film formation and dissolution. The absorption of chloroform molecules into the annealed latex film was fol lowed by the diffusion of PMMA chains into the solvent reservoir. The diffu sion coefficients of the PMMA chains were measured and found to range from 2.6 x 10(-9) to 9.7 x 10(-13) cm(2) s(-1) for the latex films of various th icknesses. Thicker films dissolved much faster than the thinner films. Mont e Carlo simulations were performed for photon transmission through a rectan gular lattice, where trap centres are introduced to simulate the effect of voids and cracks on the transparency of the latex film. As the lattice thic kness was increased, the number of trap centres decreased.