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Electro-induced two-way shape memory polymer is a kind of smart material which can realize bidirectional reversible actuation under current stimulation. However, due to the limitation of materials, there are few studies on the electro-induced two-way shape memory effect. Herein, the two-way shape memory effect of a new type of semi-crystalline thermoplastic polyamide elastomer (TPAE, T12) was systematically studied. The response strain (εact) of two-way shape memory effect for T12 under constant stress and stress-free condition could reach 16.4 % and 9.7 %, respectively. The introduction of multi-walled carbon nanotubes (CNTs) endowed the T12 material with good conductivity, and CNTs did not significantly influence the two-way shape memory performance of T12/CNTs composite. Moreover, when the content of CNTs was 5 wt%, the surface temperature of T12/CNTs composite could reach 36 °C–90 °C at a voltage of 90 V–150 V. Then, we realized the electro-induced two-way shape memory behavior of T12/CNTs composite through the construction of bilayer SEBS/T12/CNTs actuator. Therefore, T12 material, as a new two-way shape memory TPAE, has great application potential in aerospace, soft robotics, medical and other fields.

Thermoplastic polyamide elastomer (TPAE) films were prepared by selective laser sintering technology and their organic vapor sensing behaviors were investigated. The stable responsive electrical signal was attributed to the conductive pathways evolution formed by polyetheramine soft segments. And the response behaviors of the TPAE films were evaluated using organic vapors of different polarities. Unlike conventional materials that only respond to some specific organic vapors, TPAE showed a high negative vapor coefficient (NVC) effect for all tested vapors. Rapid response, high responsivity and good repeatability were observed in continuous immersion drying run (IDR) experiments at 20 °C. The sensing behaviors during the breathing tests showed a good discrimination for different ethanol vapor concentrations. This study not only provides a guidance for the preparation of organic vapor sensors with fast response, high responsivity and stable repeatability, but also provides a strategy to broaden the application of TPAE into 4D printing field.

Nowadays, there are many researches on flexible humidity sensors based on different composites, such as polymer with graphene oxide, carbon nanotubes as conductive fillers. Herein, a flexible wearable device used for humidity detection and breath monitoring was fabricated based on the molecular designable thermoplastic polyamide elastomer (TPAE). TPAE is block copolymers consisting of the polyamide hard segments and the polyether soft segments. Among them, the hard segments (PA1212 or PA6) form the crosslinking network providing resilience, and the soft segments composed of PPO and PEO endow TPAE with flexibility and solvent-responsiveness. The resistance of TPAE-based humidity sensor decreases with the increase of relative humidity (RH), exhibiting negative humidity sensitivity. Besides, it has a wide humidity monitoring range (11 %RH ∼ 91 %RH) and good fitting degree of R2 > 0.99 which is hardly influenced by bending deformation. When the humidity sensor was exposed to organic vapor (e.g. ethanol), it exhibited a faster response of astonishing 4 s. This novel block copolymer not only shows good humidity sensing performance in many aspects, but also provides a novel strategy and approach for the preparation of the humidity sensing materials afterwards.

Abstract Shape memory polyamide elastomers have attracted large attention owing to a variety of favorable properties (e.g., designable chemical structure, good thermal stability, flexibility, and elasticity, et al). However, the polyamide elastomer reported recently still lack good mechanical property. In the present work, a new type of shape memory thermoplastic polyamide elastomer (TPAE), composed of long carbon chain PA1212 and polytetramethylene ether glycol (PTMEG), is synthesized through two‐step melt polycondensation, which is named as poly(ether‐b‐amide) (PEBA). The chemical structure of PEBA is confirmed by FTIR results and it also shows excellent mechanical properties. PEBA, possessing two melting temperatures, stay in microphase separation among PTMEG soft domains and PA1212 hard domains that are amorphous and α crystal, respectively. Furthermore, PEBA can fix a temporary shape after the heated strip is twisted and cooled down and then recover to the original shape after secondary heating, which is attributed to the fixing force provided by PTMEG domains and entropy elasticity of physically cross‐linked PA1212 domains, respectively. Besides, PEBA elastomer can be reshaped between ≈190 and ≈380 °C and it also has shape memory behavior. This new kind of TPAE proposes a new smart material for sensors and soft robotics.

Anisotropic thermally conductive composites are very critical for precise thermal management of electronic devices. In this work, in order to prepare a composite with significant anisotropic thermal conductivity, polyamide 12/styrene–acrylic copolymer–boron nitride (PA12/SA–BN) composites with macro and micro double anisotropic structures were fabricated successfully using 3D printing and micro-shear methods. The morphologies and thermally conductive properties of composites were systematically characterized via SEM, XRD, and the laser flash method. Experimental results indicate that the through-plane thermal conductivity of the composite is 4.2 W/(m·K) with only 21.4 wt% BN, which is five times higher than that of the composite with randomly oriented BN. Simulation results show that the macro-anisotropic structure of the composite (caused by the selective distribution of BN) as well as the micro-anisotropic structure (caused by the orientation structure of BN) both play critical roles in spreading heat along the specified direction. Therefore, as-obtained composites with double anisotropic structures possess great potential for the application inefficient and controllable thermal management in various fields.

The development of semi-aromatic polyamides with excellent mechanical properties has always been a popular research avenue. In this work, the semi-aromatic polyamide 12T (PA12T) with the maximum tensile strength of 465.5 MPa was prepared after stretching at 210 °C 4.6 times. Wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) were used to characterize the structural evolution of semi-aromatic polyamide 12T (PA12T) after stretching at different stretching temperatures and stretching ratios. The formation mechanism of this change in mechanical properties was investigated from different aspects of the aggregated structure such as crystal morphology, crystal orientation and crystallinity. The relevant characterization results show that the crystal structure, crystal orientation and crystallinity of PA12T were the highest when the sample was pre-stretched at 210 °C, which is crucial for improving the mechanical properties of PA12T. These findings will provide important guidance for the preparation of polymer materials with excellent mechanical properties.

Abstract With the increasing demand for detection accuracy and sensitivity, dual‐band polarimetric image sensor has attracted considerable attention due to better object recognition by processing signals from diverse wavebands. However, the widespread use of polarimetric sensors is still limited by high noise, narrow photoresponse range, and low linearly dichroic ratio. Recently, the low‐dimensional materials with intrinsic in‐plane anisotropy structure exhibit the great potential to realize direct polarized photodetection. Here, strong anisotropy of 1D layered bismuth sulfide (Bi2S3) is demonstrated experimentally and theoretically. The Bi2S3 photodetector exhibits excellent device performance, which enables high photoresponsivity (32 A W−1), Ion/Ioff ratio (1.08 × 104), robust linearly dichroic ratio (1.9), and Hooge parameter (2.0 × 10−5 at 1 Hz) which refer to lower noise than most reported low‐dimensional materials‐based devices. Impressively, such Bi2S3 nanowire exhibits a good broadband photoresponse, ranging from ultraviolet (360 nm) to short‐wave infrared (1064 nm). Direct polarimetric imaging is implemented at the wavelengths of 532 and 808 nm. With these remarkable features, the 1D Bi2S3 nanowires show great potential for direct dual‐band polarimetric image sensors without using any external optical polarizer.

The rapid development of the polymeric materials market has created an urgent demand for the thermoplastic polyamide elastomer (TPAE) owing to its greater functionality, and ability to be synthesized via a facile and industrial route. In this work, a series of novel silicone-containing polyamides (PA1212/Si12) were successfully synthesized from 1,12-dodecarboxylic acid (LA), 1,12-dodecarbondiamine (DMDA), and 1,3-bis (amino-propyl) tetramethyldisiloxane (BATS), via a one-pot melt polycondensation method in the absence of a catalyst. FTIR, 1H-NMR, GPC and inherent viscosity results cohesively prove that the polymerization of monomers was well conducted, and the chemical structure was in high accordance with the design. As expected, the Si12 unit-content of the copolymers regulate the properties of the series. As the feeding ratio of BATS in the diamines increases from 5 mol% to 40 mol%, the thermal transition temperatures, Tg and Tm, decline steadily before finally stabilizing at ~6 °C and 160 °C, respectively, indicating that the co-polyamides possess improved chain flexibility but restricted crystallization ability. The conspicuous evolution in crystalline morphology of the series was observed by XRD and AFM. The increased PA Si12 phase induces the crystallized PA 1212 phase to transit from a thermally-favorable large and rigid crystal structure (α phase) to a kinetically-favorable small and ductile crystal structure (γ phase). Reflected in their stress–strain behavior, PA1212/Si12 copolymers are successfully tailored from rigid plastic to ductile elastomer. The tensile strength mildly drops from above 40 MPa to ~30 MPa while the reversible elongation increases from ~50% to approximately 350%. Accordingly, the moderate surface tension differences in the monomers facilitate the efficient conduction of the co-polymerization process, and the distributed short siloxane unit in the backbone fulfills the copolymer with desirable elasticity. Interestingly, the novel silicone-containing polyamides also display Si12 unit-content dependent flame retardancy, humidity stability, and unconventional solid-state fluorescence properties. The elastomers exhibit a low bibulous rate and anti-fouling characteristics to dye droplets and mud contamination, pass the V–1 rating (UL 94) with a constantly declining PHRR value, and emit blue luminescence under a 365 nm light source. Herein, we propose a new facile strategy for developing a high-performance and multifunctional silicone-modified polyamide, which bears promising industrialization potential. In addition, this first reported silicone-containing thermoplastic polyamide elastomer, which is self-extinguishing, anti-fouling and blue-luminescent, will further broaden the application potential of thermoplastic polyamide elastomers.