Microgels That Assemble Themselves
Shape-complementary hydrogel blocks that find their partners in water, and take microplastics with them.
Hydrogels can be made to recognize each other. Give two populations complementary shapes and opposite surface charges and they will find one another in water and lock together, a mesoscale echo of host–guest chemistry.
We photopolymerize acrylic acid and dimethylaminoethyl acrylate through shape-defined photomasks, producing microgels with matching geometry and opposing charge. Electrostatic attraction between deprotonated carboxylates and protonated amines then drives selective lock-and-key assembly, tuned by pH, ionic strength and how the mixing is done.
Loading the gels with magnetic nanoparticles turns the assembly into a tool: the blocks capture polystyrene, polycarbonate and PVC microplastics out of contaminated water, and a magnet pulls the whole assembly back out. Assembled pairs remove more than the same gels working alone, which is the part we did not expect.
Unpublished. Manuscript in preparation.
Carson J. Bruns, Associate Professor, ATLAS Institute and the Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder.