Underwater superoleophobic and magnetic hydrogel for cascade chemical reactions

Abstract

Magnetic hydrogels often suffer from low saturation magnetization and poor chemical and mechanical tolerance. Herein, we report magnetic nanoparticles (i.e. Fe₃O₄) grown in situ in an interpenetrating network containing both physical and covalent crosslinkages, which allowed the development of a high-water-content (∼95 wt%) and chemically (e.g. stable at extreme pH values of 1 and 12) and mechanically (Young's modulus of 550 kPa) stable magnetic hydrogel with high saturation magnetization (85 emu g⁻¹). Moreover, the inherent high water content endowed the magnetic hydrogel with underwater superoleophobicity (OCA 160°), which enabled no-loss transport and mixing of liquid droplets as well as a cascade droplet (microliters) chemical reaction underwater through on-demand application of external magnetic field.