Core-shell colloids and hollow polyelectrolyte capsules based on diazoresins

Hollow polyelectrolyte microcapsules containing diazoresins (DZR) were fabr icated by the layer-by-layer self-assembly of a polycation, DZR, in alterna tion with poly(styrenesulfonate) (PSS) onto polystyrene (PS) particles, fol lowed by dissolution of the PS core by tetrahydrofuran (THF). The multilaye r film buildup on the colloids was observed by UV-visible spectroscopy, sin gle particle light scattering (SPLS), and transmission electron microscopy (TEM). The data confirmed regular and stepwise layer formation of DZR and P SS on the colloid particles, with a thickness of about 10 nm fur each DZR/P SS bilayer when exposed to aqueous solution, and approximately 5 nm in the "dry state". The photosensitive nature: of the DZR layers was exploited to construct highly stable, covalently attached (polymerized) films by exposur e of the: ionic self-assembly cl DZR/PSS multilayer films to UV-irradiation . TEM and atomic force microscopy (AFM) confirmed the formation of hollow D ZR/PSS multilayer capsules. Osmotic pressure experiments followed by confoc al laser scanning microscopy revealed a high mechanical stability of the ho llow DZR/PSS capsules. The mechanically robust polymerized multilayer films on the colloids and as free-standing three-dimensional hollow capsules are more stable in various chemical environments (i.e., resistant to etching b y solvents) than their ionically linked counterparts.