Wall-coated polymer brushes as catalytic support for organic reactions in continuous-flow microreactors

A microreactor platform has been realized as an enabling tool to perform synthetic organic reactions. The platform provides advantages over batch reactions, thus allowing: reactions with a potentially explosive reagent, the execution of heterogeneous catalysis by immobilizing catalysts onto the interior of a microchannel surface, and the performance of controlled formation of supramolecular nanoparticle clusters. In the first part, the regioselective ring opening of various types of aromatic and aliphatic epoxides with hazardous sodium azide to give vicinal azido alcohols, was studied in a microreactor with and without pillars in the channels. The reactions performed in microreactors with pillars displayed better conversions compared to analogous lab scale reactions. In the second part, polymer brush layers with thicknesses of a few hundred nanometers were used as a support for catalyst immobilization on the interior of microchannel walls. Polymer brushes support higher catalyst loadings as compared to monolayers. Different types of catalysts were implemented inside the microreactor. Their catalytic efficiency was studied for different reactions. In the last part, self-assembly of supramolecular nanoparticle clusters (SNPCs) has been demonstrated in a microfluidic device, by controlling the diffusive mixing of the constituting supramolecular building blocks. Microreactors are a valuable tool to study homogeneous and heterogeneous reactions in a safe and efficient way. Polymer brushes have proven to be a robust platform to immobilize various catalysts on the interior of a microchannel for performing supported catalysis. In addition, microreactors provide a unique environment for the controlled fabrication of nanomaterials compared to lab-scale equipment. So, microreactors have the potential to become a common experimental device for chemists in various disciplines.