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This article reports a chromic polymer, which is responsive to its shape memory properties and has both the behavior of shape memory polymers and chromic materials. We employed a strategy to fabricate such a smart material, which represents a new principle for making chromic materials. This material is made of shape memory polyurethane with tetraphenylethylene units (0.1 wt %) covalently connected to the soft-segments (PCL, M w 5 4000). The material displays biocompatibility, shape fixity of 88-93%, and almost 100% shape recovery and has reversible mechanochromic, solvatochromic, and thermochromic shape memory effect. The memory chromism represented by the reversible change of emission intensity shows negative correlation with shape fixity, temperature, and existence of solvent. It may be explained that when the soft segments are molten or dissolved in solvent, the shape recovery switch is open, the AIE units are free from crystal binding and can migrate easily to larger areas, thus the AIE units/particles are far apart from each other and the barrier for rotation of phenyl groups is reduced, which lead to the reduction of emission intensity, appeared by no colors or pale colors, and vice versa. Since the switch is a fundamental structural character of SMPs, the shape memory properties have led to the chromism and we call this memory chromic. Shape memory polymers (SMPs) are one group of the most promising smart materials and have drawn increasing interests because of their great potential in different applications such as sensors, actuators, biomedical devices, and textiles. [1][2][3][4][5][6][7][8] Typical SMPs have networks realized by the formation of well separated hard and soft phases. The hard phase acts as netpoints, which determine the permanent shape while the soft phase as the switch and can immobilize the temporary shape with different transition stimuli. Take the thermal sensitive SMPs as an example: when they are deformed above the transition temperature (T trans ) of soft segments and then cool down, the network will be fixed and the internal stress will be stored (such process is called programming). Upon heating to T trans or above, the internal stress will be released which enables the recovery of the polymer to the origin shape. With the rapid development of SMPs, recent research interest moves to the integration of SMPs with additional functions such as biodegradability, drug release, and thermochromism.

Conductive hydrogels have attracted great attention due to their promising applications in wearable sensors. However, developing conductive hydrogels with excellent sensor properties and multiple stimuli responsiveness for smart wearable devices is still a challenge. This paper presents a facile synthetic method of a crosslinked chitosan quaternary ammonium salt and liquid metal (CHACC-LM) composite hydrogel with temperature-stress bimodal sensing for smart wearable sensor. LM as liquid fillers toughen the hydrogel matrix (stress: 1.11 MPa) and enhance the hydrogel extensibility (strain: 233%). The CHACC-LM hydrogel exhibits conductivity , excellent antibacterial properties (> 99%), an electrical self-healing property, and strain sensitivity (GF = 1.6). In addition, the CHACC-LM hydrogel can be used as wearable flexible sensors with the ability of monitoring human activities directly and the distinguished ability of discerning subtle motions (handwriting). It also shows sensitivity in the external environment such as low temperature, thermal response, and water solution. Importantly, the composite hydrogel simultaneous response to different stress and temperature stimuli. Furthermore, the CHACC-LM hydrogel can be used for gesture recognition and to control the manipulator in human-computer interaction. All these properties provide a great scope for researchers to achieve practical advances in smart wearable sensors.

Magnetic FeO nanospheres coated with Mg-MOF-74 have been facilely prepared via epitaxial growth. Owing to the intrinsic hydrophilic pore surface and size-exclusive properties of Mg-MOF-74, the FeO@Mg-MOF-74 core-shell nanoparticles show effective and selective enrichment of 441 N-glycosylation sites of 418 glycopeptides from 125 glycoproteins in 1 μL of human serum.

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