Core-shell particles and hollow shells containing metallo-supramolecular components

Core-shell particles consisting of a polystyrene (PS) latex colloidal core and Fe(II) metallo-supramolecular polyelectrolyte (Fe(II)-MEPE)/poly(styrenesulfonate) (PSS) multilayer shells were fabricated by the consecutive assembly of Fe(II)-MEPE and PSS on PS particles. The layers were deposited under conditions where the Fe(II)-MEPE and PSS are oppositely charged, thereby utilizing electrostatic attractions for multilayer buildup. Formation of Fe(II)-MEPE/PSS multilayers on weakly cross-linked melamine-formaldehyde (MF) particles, followed by MF particle decomposition and removal, resulted in hollow Fe(II)-MEPE/PSS shells. The Fe(II)-MEPE/PSS multilayer shell on the colloidal particles and the Fe(II)-MEPE/PSS hollow shells were found to be stable, resisting decomposition upon exposure to acidic solutions or chelating agents. PS latices as small as 70 nm in diameter were also employed as templates for the successful fabrication of Fe(II)-MEPE/PSS and poly(allylamine hydrochloride)/PSS multilayer shells. These results demonstrate that our approach can be extended to colloidal templates with diameters less than 100 nm. This work represents a first study of structurally well-defined metallo-supramolecular polyelectrolyte-colloid assembles combining the functional units from supramolecular chemistry with the restricted dimensionality of colloids.