Direct 3D Printing of Catalytically Active Structures

3D
printing of materials with active functional groups can provide
custom-designed structures that promote chemical conversions. Herein,
catalytically active architectures were produced by photopolymerizing
bifunctional molecules using a commercial stereolithographic 3D printer.
Functionalities in the monomers included a polymerizable vinyl group
to assemble the 3D structures and a secondary group to provide them
with active sites. The 3D-printed architectures containing accessible
carboxylic acid, amine, and copper carboxylate functionalities were
catalytically active for the Mannich, aldol, and Huisgen cycloaddition
reactions, respectively. The functional groups in the 3D-printed structures
were also amenable to postprinting chemical modification. As proof
of principle, chemically active cuvette adaptors were 3D printed and
used to measure in situ the kinetics of a heterogeneously catalyzed
Mannich reaction in a conventional solution spectrophotometer. In
addition, 3D-printed millifluidic devices with catalytically active
copper carboxylate complexes were used to promote azide–alkyne
cycloaddition under flow conditions. The importance of controlling
the 3D architecture of the millifluidic devices was evidenced by enhancing
reaction conversion upon increasing the complexity of the 3D prints.