Xiaoxia Le

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.

Mussel-inspired multifunctional supramolecular hydrogels with self-healing, shape memory and adhesive properties

A novel multifunctional supramolecular hydrogel with self-healing, shape memory and adhesive properties is successfully developed on the basis of dynamic phenylboronic acid (PBA)–catechol interactions. The reversible nature of PBA–catechol bonds renders the hydrogel with outstanding self-healing and shape memory behavior, and the mussel-inspired catechol moieties generate fascinating adhesive properties.

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.

A Novel Anisotropic Hydrogel with Integrated Self-Deformation and Controllable Shape Memory Effect

Although shape memory polymers have been highlighted widely and developed rapidly, it is still a challenging task to realize complex temporary shapes automatically in practical applications. Herein, a novel shape memory hydrogel with the ability of self-deformation is presented. Through constructing an anisotropic poly(acrylic acid)-polyacrylamide (PAAc-PAAm) structure, the obtained hydrogel exhibits stable self-deformation behavior in response to pH stimulus, and the shapes that formed automatically can be fixed by the coordination between carboxylic groups and Fe3+ ; therefore, self-deformation and shape memory behaviors are integrated in one system. Moreover, the magnitude of auto-deformation and shape memory could be adjusted with the concentration of corresponding ions, leading to programmable shape memory and shape recovery processes.

Shape Memory Hydrogels with Simultaneously Switchable Fluorescence Behavior

Realization of shape memory process in polymeric hydrogels at ambient condition is a significant development to shape memory materials. The sound understanding of the dynamic shape memory process is fundamentally important but limited. Here, a novel shape memory hydrogel with simultaneously switchable fluorescence behavior is developed. The hydrogel is prepared by incorporating a pH-responsive fluorescent molecule, perylene tetracarboxylic acid, into chitosan-based hydrogel, and the assembly and disassembly of chitosan chains into microcrystals upon the trigger of pH are applied as reversible crosslinks to achieve shape memory effect. Therefore, the formation and disassociation of microcrystalline chitosan, and the switchable fluorescence performance happen concurrently, which bring convenience to monitoring the shape memory process by fluorescent imaging. Moreover, the erasable fluorescence behavior also gives the hydrogel potential applications in information storage.