Microgels as Nanoreactors: Applications in Catalysis

Abstract

We review recent work on the use of “smart” microgel particles as “nanoreactors” for the immobilization of metal nanoparticles as well as enzymes. A general feature of the microgel systems under consideration is their ability to react to external stimuli such as the pH or temperature of the system. Special emphasis is given to our recent research work on thermosensitive core–shell microgel particles composed of a polystyrene core and a crosslinked poly(N-isopropylacrylamide) shell. Work done on these core–shell systems is compared to developments in the investigation of similar systems. Recently, it has been shown that these core–shell microgels can be used as “nanoreactors” for the immobilization of metal nanoparticles. The metal nanocomposite particles exhibit a “smart” catalytic behavior inasmuch as the catalytic activity of nanoparticles can be modulated through the volume transition that takes place within the thermosensitive shell of the carrier system. Moreover, microgel particles can work as efficient carrier systems for the immobilization of enzymes. The dependence of the enzymatic activity on temperature can also be manipulated by the temperature-dependent swelling behavior of the microgel. Thus, the microgel particles present an excellent “active” carrier system for applications in catalysis.