Metal Containing Complex Coacervate Core micelles

    Environmentally responsive microgels have been subjects of great interest in the last two decades due to their versatile applications in fields like drug delivery, chemical separation and catalysis [1]. In our previous study, thermosensitive polystyrene core-shell microgel particles, in which the core consists of polystyrene whereas the shell consists of a poly (N-isopropylacrylamide) (PNIPA) network, have been used as “nanoreactors” for the deposition of metal nanoparticles (such as Ag, Au, Pd, and Pt) [2]. We demonstrate that the catalytic activity of the metal nanoparticles can be tuned by the volume transition within the microgel by using the catalytic reduction of 4-nitrophenol as the model reaction [3]. In addition to this, thermosensitive Au-PNIPA yolk-shell microgel systems in which a single Au-nanoparticles is immobilized in a hollow shell of PNIPA have been developed [4]. The catalytic selectivity of this hybrid system can be tuned by temperature as is shown by the competitive reduction of the hydrophilic 4-nitrophenol and the hydrophobic nitrobenzene by borohydride.

    In the present study, we report a facile and novel method for the fabrication of Cu2O@PNIPA core-shell nanoreactors using Cu2O nanocubes as the core [5]. The PNIPA shell not only effectively protects the Cu2O nanocubes from oxidation, but also improves the colloidal stability of the system. The Cu2O@PNIPA core-shell microgels can work efficiently as photocatalyst for the decomposition of methyl orange under visible light. A significant enhancement in the catalytic activity has been observed for the core-shell microgels compared with the pure Cu2O nanocubes. Most importantly, the photocatalytic activity of the Cu2O nanocubes can be further tuned by the thermosensitive PNIPA shell. A theory for the diffusion- and solvation-controlled contribution to the reaction rate of such a “nanoreactor” has been also discussed [6]. Hence, the microgel particles present an “active” carrier system for applications in catalysis.