Natural Lipid Inspired Hydrogel-Organogel Bilayer Actuator With A Tough Interface And Multiresponsive, Rapid, And Reversible Behaviors

The development of hydrogel-organogel bilayer films has greatly promoted the application of asymmetric structures in bionics, biointegrated electronics, and other basic industries. However, the ability to bond the hydrogel and organogel tightly remains a significant challenge. Herein, we propose a simple onepot method for the fabrication of multiresponsive hydrogel-organogel bilayer films, consisting of a hydrophobic poly(butyl acrylate) (polyBA) layer, a salt-/thermo-responsive poly(3-(1-(4-vinylbenzyl)-1H-imidazol-3-ium-3-yl) propane-1-sulfonat) (poly-VBIPS) layer, and interfacially distributed vinyl-functionalized nanoparticles. The presence of functionalized nanoparticles leads to strong adhesion between the hydroge and organogel via copolymerization between the hydrogel and organogel precursors. Since the hydrophobic organogels and hydrophilic hydrogels exhibit independent swelling-shrinking behaviors, the resultant bilayer films undergo rapid, large-amplitude, reversible, and repeatable bidirectional bending under various external stimuli, such as temperature, salt solutions, and organic solvents. The excellent multiresponsive bending behaviors were further demonstrated in biomimetic manipulators which show excellent "capture-transport-release" complex mechanical motions. Additionally, on the basis of the salt response of polyVBIPS, a conceptual hydrogel-organogel bilayer pipe has been designed for the removal of oil/seawater pollution. Overall, this work provides a new strategy for enhancing interfacial strength in immiscible binary systems. A new hydrogel-organogel bilayer film has been developed with great potential for use in the applications of soft robots and sewage treatment systems.