Microgels are soft polymer colloids consisting of crosslinked polymer chains swollen in a solvent. Microgels exhibit exciting properties that lie between linear polymers and three-dimensional polymer networks. Stimuli-responsive microgels can change their size, softness and surface charge with changing of pH, light, solvent or temperature.<br/>Unique properties of microgels like porous structure, chemical functionality, and adaptability to different solvents, making them extremely attractive colloidal carrier systems for application in catalysis. Open microgel structure and the presence of functional groups provide the possibility to attach selectively molecular catalysts and to control their localization at the surface or in the interior. The porous structure of the microgel also allows diffusion of small molecules (reagents, solvents) and the diffusion rate can be regulated by the stimuli-triggered degree of swelling of the polymer network. Microgels can adapt to different environments and are easily reversibly transferred from water to organic solvents. On the other hand, microgels are sub-micrometer sized colloids making their handling, in terms of purification or separation, much easier compared to molecular catalysts.<br/>This contribution will focus on the controlled integration of catalytically active nanoparticles (Au, Pd, CeO<sub>2</sub>) along with organocatalysts (proline, quinine) and enzymes into microgels. Different synthesis strategies were developed to obtain responsive hybrid microgels with variable amount and controlled distribution of catalytically active sites in the microgel network. The incorporation of nanoparticles into microgels was achieved by three approaches: a) in-situ NPs growth in microgels; b) diffusion-based loading of NPs into microgels and c) encapsulation of nanoparticles during microgel formation. We demonstrate that the loading degree of NPs in microgels as well as their size and morphology can be precisely controlled. These synthesis approaches allow fabrication of highly efficient microgel-based catalysts for applications in oxidation, hydrogenation and C-C coupling reactions.

Nanoparticle-modified microgels: Towards adaptive hybrid catalysts

2019 Spring National Meeting

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