Fabrication of shape-tunable micromotors based on mass transfer and phase separation

Abstract

Bubble-propelled micromotors with controlled size and morphologies are developed by a simple and flexible strategy for efficient wastewater treatment. Controllably and spontaneously evolved complex emulsions from microfluidics are used as templates for continuous fabrication of the micromotors in one step. As the flow rate ratio of disperse phase II (dextran aqueous solution) to disperse phase I (ethoxylated trimethylolpropane triacrylate and poly(ethylene glycol) diacrylate mixture) increases, the micromotor can evolve from a double spherical shape to a snowman shape. By fine tuning the fabrication parameters, we can fabricate micromotors loading with MnO2 nanoparticles on the concave surface, Fe3O4 nanoparticles on the convex surface and Fe3O4 nanoparticles inside the micromotors simultaneously. The obtained micromotors are propelled by O2 bubbles generated from MnO2-triggered catalytic decomposition of H2O2, with the highest speed at about 86.4 μm/s. Fe3O4-induced Fenton reaction can account for the methylene blue degradation. Our study provides an easy and effective strategy for the one-step synthesis of spherical and non-spherical micromotors, which can be potentially used for highly efficient wastewater treatments. Graphical Abstract: [Figure not available: see fulltext.].