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 particles labeled with phenanthrene or anthracene comprised of either poly(n-butyl methacrylate) (PBMA) or a copolymer of n-butyl methacrylate with a poly(ethylene oxide) (PEO) macromonomer, co(PBMA-PEO). Interparticle polymer diffusion was followed by nonradiative electronic energy transfer (DET) between electronically excited phenanthrene and anthracene. A model of energy transfer that considers both the topological constraints and the heterogeneous distributions of donors and accepters is presented. The analysis of the phenanthrene decay curves allows calculation of the diffusion coefficient as a unique parameter, for several annealing times. The values recovered decrease initially with annealing 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 macromonomer, the fraction of mixing increases on drying, but during annealing the diffusion coefficients remain equal to that of PBMA without PEO.