Mesoscopic Supramolecular Assembly of Stereolithographically Printed Microgels

Microgels that assemble upon issuing of a trigger open up miscellaneous applications in soft robotics, drug delivery, and life-like materials, due to their unique physical and chemical properties. In this work, a novel hydrogel photoresist system is formulated, consisting of 2-hydroxyethyl acrylate, ethylene glycol diacrylate, and phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide, as well as redox-sensitive supramolecular host-guest association motifs. Complex and multi-compartmented geometries with precisely located recognition motifs are printed in high resolution, resulting in multifunctional structured microgel building blocks for mesoscopic self-assembly. An enzymatic feedback system is employed to dissipatively assemble and disassemble the redox-active microgel building blocks in a temporally and spatially controlled pathway. The self-assembling photoresist system is characterized in terms of the lower critical solution temperature, swelling behavior, and printability. The present work provides new perspectives for the design of tailor-made mesoscopic microgels with customizable functionality and high applicability for various technological applications. Microgels represent soft thermally actuatable building blocks that can be assembled into larger structured architectures using supramolecular recognition motifs. Here, compartmented mesoscopic microgel building blocks are produced by stereolithographic 3D printing, featuring supramolecular recognition motifs only at designated points in the structure. An enzymatic feedback system is employed to guide the building blocks along a redox-potential gradient leading to temporal and spatial control of their assembly and disassembly. The building blocks and assemblies can be thermally actuated to collapse or swell.image