LATEX FILM FORMATION PROBED BY NONRADIATIVE ENERGY-TRANSFER - EFFECT OF GRAFTED AND FREE POLY(ETHYLENE OXIDE) ON A POLY(N-BUTYL METHACRYLATE) LATEX

The formation of solid films from latex dispersions is studied using p articles labeled with phenanthrene or anthracene comprised of either p oly(n-butyl methacrylate) (PBMA) or a copolymer of n-butyl methacrylat e with a poly(ethylene oxide) (PEO) macromonomer, co(PBMA-PEO). Interp article polymer diffusion was followed by nonradiative electronic ener gy transfer (DET) between electronically excited phenanthrene and anth racene. A model of energy transfer that considers both the topological constraints and the heterogeneous distributions of donors and accepte rs is presented. The analysis of the phenanthrene decay curves allows calculation of the diffusion coefficient as a unique parameter, for se veral annealing times. The values recovered decrease initially with an nealing time, which was attributed mainly to the polydispersity of the PBMA. The addition of a small percentage of low molecular weight PEO (in the form of nonylphenolethoxylate) to the PBMA particles increases the diffusion coefficient, this effect resulting from the increase of the polymer free volume in the film. When the same percentage of PEO is incorporated in the PBMA polymer chain in the form of a grafted mac romonomer, the fraction of mixing increases on drying, but during anne aling the diffusion coefficients remain equal to that of PBMA without PEO.