Polymer microgels are microscopic particles made from a three-dimensional polymer network that can swell in a solvent. If that solvent is water, these particles are so-called hydrogels. Utilizing microfluidics, uniform hydrogel particles can be readily obtained from water-in-oil emulsion droplets in a size range from 10s to 100s of micrometers. While polymer microgels have been frequently utilized as drug delivery systems, for cell encapsulation or as reversibly swelling sensors and actuators on a single-particle level, recent literature has also demonstrated the versatility of polymer microgels to design bioinks made from multi-particle suspensions, e.g., for tissue engineering. Yet, common methods to process such microgel suspensions into three-dimensional (3D) microgel assemblies – so-called supragels – lack spatial control over placement and assembly of microgel unit cells, which is crucial, however, when different microgel species are to be combined into one integrated polymer material.
On this account, this talk focuses on the design of defined supragels made from polymer microgels and highlights three research challenges: (1) to provide sufficient quantities of tailored microgels via microfluidics for cross-scale polymer material design; (2) to assemble microgels with a cross-linker chemistry acting independent from their prior gelation; and (3) to inter-connect microgels with spatial control.
In short, these challenges are addressed by (1) developing 3D-printed microreactors integrating multiple stages of emulsion processing for high-throughput microgel formation, (2) by exploring a [2+2] cycloaddition reaction based on dimethyl maleimide cross-linking, and (3) by developing a material-independent actuation platform that can individually position microgels towards multi-particle integration in supragels.