Flexible strain sensors have shown great application value in wearable devices. In the past decades, researchers have spent numerous efforts on developing high-stretchability, excellent dynamic durability, and large linear working range flexible strain sensors and shaped a series of important research results. However, the viscoelasticity of the elastic polymer is always a big challenge to develop a flexible sensor. Here, to overcome this challenge, we developed a novel self-repairing carbon nanotubes/ethylene vinyl acetate (CNTs/EVA) fiber strain sensor prepared by embedding the CNTs on the surface of the swollen shape memory EVA fiber via the ultrasonic method. The CNTs/EVA fiber strain sensors responded with significant results, with high stretchability (190% strain), large linear working range (up to 88% strain), excellent dynamic durability (5000 cycles), and fast response speed (312 ms). In addition, the permanently damaged conductive network of the strain sensors, caused by the viscoelasticity of elastic polymer, can restore above the transforming temperature of the shape memory CNTs/EVA fiber. Moreover, the performance of the restored strain sensors was almost as same as that of the original strain sensors. Furthermore, human health monitoring tests show that the CNTs/EVA fiber has a broad application prospect for human health monitoring in wearable electronic devices.

Developing an electromagnetic interference (EMI) shielding material with lightweight, ultrathin, and high‐performance complex electromagnetic wave pollution has become a research trend. Here, a novel ultrathin ordered reduced graphene oxide fiber (oRGOF) membranes are reported with wrinkles, grooves, and hierarchical structure by a simple assembly process based on wet spinning. The results show that the oRGOF membranes have obvious anisotropic conductivity and directional electromagnetic shielding properties. The measured electrical conductivity along the fiber axial direction (0°) is higher than that along the fiber radial direction (90°). Furthermore, the EMI shielding performance difference under different rotation angles is more than 25 dB (31.0 dB at 0°, 4.9 dB at 90°). The thickness of the resultant oRGOF membrane is 0.03 mm and area density of 0.9 mg cm−2, and the specific EMI SE (SSE/t) is 33333 dB cm2 g−1 along the fiber axis. The oRGOF membranes show flexible and durable performance under repeated bending and straightening cycles tests over 160 times, without significant reduction of the shielding performance. Thus, the ultrathin, ultralight, and anisotropic oRGOF electromagnetic interference shielding membrane have broad prospects for both civilian and military applications.

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Shape memory epoxy with self‐healing ability has received much more academia and industry attention. In this work, 4‐aminophenyl disulfide containing disulfide bonds was used to replace the traditional epoxy resin‐curing agent, and the waterborne epoxy resin (sWEP) was composited with the polydopamine (PDA) nanoparticles with photothermal conversion effect through the melt mixing and hot‐press molding. As revealed, the addition of 1 wt% PDA increases the tensile strength of sWEP from 36.1 to 50.3 MPa. Specifically, the shape memory properties of the PDA/sWEP composite as manifested by a ca. 97.4% shape memory fixing ratio and ca. 67.8% shape memory recovery ratio. Moreover, the PDA/sWEP composite had the temperature‐dependent thermosetting and thermoplastic conversion capabilities, which can be programmed to a new permanent shape via a photothermal‐induced plasticity process.

One-dimensional shape memory polymer fibers (SMPFs) have obvious advantages in mechanical properties, dispersion properties, and weavability. In this work, a method for fabricating semi-crystallization ethylene-vinyl acetate copolymer (EVA) fiber with two-way shape memory effect by melt spinning and ultraviolet (UV) curing was developed. Here, the effect of crosslink density on its performance was systematically analyzed by gel fraction measurement, tensile tests, DSC, and TMA analysis. The results showed that the crosslink density and shape memory properties of EVA fiber could be facilely adjusted by controlling UV curing time. The resulting EVA fiber with cylindrical structure had a diameter of 261.86 ± 13.07 μm, and its mechanical strength and elongation at break were 64.46 MPa and 114.33%, respectively. The critical impact of the crosslink density and applied constant stress on the two-way shape memory effect were analyzed. Moreover, the single EVA fiber could lift more than 143 times its own weight and achieve 9% reversible actuation strain. The reversible actuation capability was significantly enhanced by a simple winding design of the single EVA fiber, which provided great potential applications in smart textiles, flexible actuators, and artificial muscles.

Electrothermally‐driven shape‐memory composites (EDSMCs) are promising candidates in the field of actuators; however, they are still unable to deliver both substantial stretching strain and precise strain control, which limits their potential applications. A carbon nanotube (CNT) EDSMC composite made from ethylene‐vinyl acetate (EVA) is fabricated in this study using a novel hot‐pressing and xylene‐aided ultrasonic adsorption two‐step procedure to overcome this problem. Because of the outstanding electrical response of the CNT/EVA EDSMC, even at 50% tensile strain, it can accomplish electrothermally‐driven melting‐induced contraction (an extraordinary working limit for shape memory polymers‐based actuators). A large reversible strain and precise strain control can be integrated simultaneously with crystallization‐induced elongation at different cooling time. In addition, programmable actuation behaviors are made possible by the CNT/EVA EDSMC, which can generate predictable and diverse strain changes. Furthermore, the lightweight CNT/EVA EDSMC demonstrates good load capacity and can lift an object to 1000 times its weight. The CNT/EVA EDSMC shows durable performance under repeated elongation and contraction cycles tests over 100 times, without significant reduction of the strain precision, and had broad prospects for both engineering devices and robotics.

One-dimensional shape memory polymer fibers (SMPFs) have obvious advantages in mechanical properties, dispersion properties and weavability. In this work, a method for fabricating semi-crystallization ethylene-vinyl acetate copolymer (EVA) fiber with two-way shape memory effect by melt spinning and ultraviolet (UV) curing was developed. Here, the effect of crosslink density on its performance was systematically analyzed by gel fraction measurement, tensile tests, DSC and TMA analysis. The results showed that the crosslink density and shape memory properties of EVA fiber could be facilely adjusted by controlling UV curing time. The resulting EVA fiber with cylindrical structure had a diameter of 247.13 ± 10.07 μm, and its mechanical strength and elongation at break were 64.46 MPa and 114.33%, respectively. The critical impact of the crosslink density and applied constant stress on the two-way shape memory effect were analyzed. Moreover, the single EVA fiber could lift more than 143 times its own weight and achieve 9% reversible actuation strain. The reversible actuation capability was significantly enhanced by a simple winding design of the single EVA fiber, which provided great potential applications in smart textiles, flexible actuators and artificial muscles.