Chunxin Ma

A multi-responsive hydrogel with a triple shape memory effect based on reversible switches

A novel multi-responsive shape memory hydrogel is described. The hydrogel shows multi-responsive shape memory performance and a programmable triple shape memory effect based on dual multi-responsive reversible switches, which will inspire the design and fabrication of novel shape memory systems.

Fe3+-, pH-, Thermoresponsive Supramolecular Hydrogel with Multishape Memory Effect

Poor, nontunable mechanical properties as well as finite shape memory performance pose a barrier to shape memory hydrogels to realize practical applications. Here, a new shape memory hydrogel with tunable mechanical properties and multishape memory effect was presented. Three programmable reversible systems including PBA-diol ester bonds, AAc-Fe3+, and coil-helix transition of agar were applied to memorize temporary shapes and endow the hydrogel with outstanding multishape memory functionalities. Moreover, through changing the cross-linking densities, the mechanical properties of the as-prepared hydrogel can be adjusted.

Mimosa inspired bilayer hydrogel actuator functioning in multi-environments

Hydrogel-based actuators have attracted significant attention and shown promising applications in many fields. However, most hydrogel actuators can only act in aqueous media, which dramatically limits their applications. Hence, the realization of hydrogel actuators that function under non-aqueous conditions still remains a significant challenge. Inspired by the water self-circulation mechanism that contributes to the motion of Mimosa leaves, we herein present a general strategy towards designing hydrogel actuators that can generate motions in water, oil and even in open-air environments. A hydrogel with a reverse thermal responsive bilayer composite structure was prepared, composed of a hydrogel layer derived from a polymer featuring a lower critical solution temperature (LCST layer) and a hydrogel layer derived from a polymer featuring an upper critical solution temperature (UCST layer). Upon heating, water molecules were transferred from the LCST layer to the UCST layer within the bilayer hydrogel, while under cooling the reverse process took place, allowing for an actuation even in non-aqueous environments. This water self-circulation within the bilayer hydrogel enabled a bending of the hydrogel and hence offers a smart strategy yet with a new idea for actuators working in multi-environments. Such hydrogel actuators may provide new insights for the design and fabrication of intelligent soft materials for bio-inspired applications.

A Multiple Shape Memory Hydrogel Induced by Reversible Physical Interactions at Ambient Condition

A novel multiple shape memory hydrogel is fabricated based on two reversible physical interactions. The multiple shape memory property is endowed by a simple treatment of soaking in NaOH or NaCl solutions to form chitosan microcrystal or chain-entanglement crosslinks as temporary junctions.