Study of bulk morphology of polymer latex films using laser confocal fluorescence microscopy

Unlabeled poly(methyl methacrylate) (PMMA) and polystyrene (PSt) latex particles as well as covalently fluorescent dye labeled PMMA latex particles (FPMMA) were prepared by emulsifier free emulsion polymerization and dispersion polymerization, respectively. The surface and bulk morphology of the polymer latex mixture (FPMMA/PMMA or FPMMA/PSt, weight ratio: 1/99) filmed by evaporation at room temperature was studied by laser confocal fluorescence microscopy (LCFM). It was concluded from the LCFM images that labeled PMMA domains obviously coagulated in PSt matrix not only on the surface but also in the inner layers of the latex film. Furthermore, PMMA was richer in the middle layers but poorer on the surface layer or the layers near to the substrate for the polymer latex films.