Polymer microcapsules loaded with Ag nanocatalyst as active microreactors

Abstract

We report on the fabrication of a new complex catalytic system composed of silica-supported silver nanoparticles (AgNP) encapsulated inside polymer microcapsules (MC)s. The silver nanocatalyst itself was obtained by reduction of silver salt in the presence of SiO₂ particles acting as AgNP carriers, to provide a complex Ag/SiO₂ catalyst with the Ag surface completely free of capping agents. Ag/SiO₂ particles were enclosed inside the interior of polymer microcapsules. Due to the presence of the hydrophobic shell on the MC surface, catalytic reactions become feasible in an organic solvent environment. On the other hand, the hydrophilic nature of the MC interior forces the water-soluble reactants to concentrate inside the capsules which act as microreactors. Based on the example of catalytically driven reduction of 4-nitrophenol we demonstrate that encapsulated Ag/SiO₂ particles possess enhanced catalytic activity as compared to the catalyst being freely dispersed in reaction medium.