Novel encapsulated functional dye particles based on alternately adsorbed multilayers of active oppositely charged macromolecular species

A comprehensive study of the encapsulation of 11 functional dyes belonging to several chemical groups and subgroups is presented. Layer-by-layer poly- electrolyte adsorption at dye crystal surfaces as well as the removal of th e crystal surfaces as well as the removal of the crystal core to obtain sem ipermeable multilayer microcapsules is conducted. Dye crystals are alternat ely coated by poly(allylamine hydrochloride) (PAH), poly(styrene sulfonate) (PSS), poly(diallyldimethylammonium chloride) (PDADMAC) using a combinatio n of electrostatic, hydrophobic and van der Waals interactions. It is remar kable that the uncharged organic crystals have successfully been coated wit h PSS without using any amphiphile. The introduction of a water-soluble she ll on a functional dye crystal may be of importance in various technologies . We characterized the prepared multilayers at the particle surface or in t he microcapsule (shell) by scanning force microscopy and confocal laser sca nning microscopy.