Stretchable electronics, which can retain their functions under stretching, have attracted great interest in recent decades. Elastic substrates, which bear the applied strain and regulate the strain ...distribution in circuits, are indispensable components in stretchable electronics. Moreover, the self‐healing property of the substrate is a premise to endow stretchable electronics with the same characteristics, so the device may recover from failure resulting from large and frequent deformations. Therefore, the properties of the elastic substrate are crucial to the overall performance of stretchable devices. Poly(dimethylsiloxane) (PDMS) is widely used as the substrate material for stretchable electronics, not only because of its advantages, which include stable chemical properties, good thermal stability, transparency, and biological compatibility, but also because of its capability of attaining designer functionalities via surface modification and bulk property tailoring. Herein, the strategies for fabricating stretchable electronics on PDMS substrates are summarized, and the influence of the physical and chemical properties of PDMS, including surface chemical status, physical modulus, geometric structures, and self‐healing properties, on the performance of stretchable electronics is discussed. Finally, the challenges and future opportunities of stretchable electronics based on PDMS substrates are considered.
Elastic substrates, especially poly(dimethylsiloxane) (PDMS) substrates, are indispensable components for emerging stretchable electronics. Detailed design concepts and fabrication strategies for structured, patterned, and self‐healing PDMS substrates, and their contributions in enhancing the mechanical performance of stretchable electronics are discussed. Future perspectives and challenges in the development of stretchable and self‐healing PDMS substrates are highlighted.
The nanoporous metal–organic frameworks (MOFs) “armor” is in situ intergrown onto the surfaces of carbon fibers (CFs) by nitric acid oxidization to supply nucleation sites and serves as a novel ...interfacial linker between the fiber and polymer matrix and a smart cushion to release interior and exterior applied forces. Simultaneous enhancements of the interfacial and interlaminar shear strength as well as the tensile strength of CFs were achieved. With the aid of an ultrasonic “cleaning” process, the optimized surface energy and tensile strength of CFs with a MOF “armor” are 83.79 mN m–1 and 5.09 GPa, for an increase of 102% and 11.6%, respectively. Our work finds that the template-induced nucleation of 3D MOF onto 1D fibers is a general and promising approach toward advanced composite materials for diverse applications to meet scientific and technical demands.
In this work, calcium alginate (Ca-SA)/deacetylated konjac glucomannan (DKGM) blend films were prepared by Ca2+ crosslinking of sodium alginate (SA) and deacetylation of konjac glucomannan (KGM). The ...structure analysis by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetry (TGA) indicated that there was a strong interaction between Ca-SA and DKGM, which was resulted from the Ca2+ crosslinking of SA and intermolecular hydrogen bonds caused by the removal of acetyl groups on molecular chains of KGM, i.e. deacetylation of KGM. The obtained property findings revealed that the surface smoothness and transparency of the blended films were decreased with increasing the KGM/DKGM content. Moreover, the deacetylation of KGM decreased the swelling capacity of the blended films, while improved the thermal stability, surface hydrophobicity, and tensile strength of the blended films. In conclusion, this study provided an alternative improvement for the development of polysaccharide based packaging materials.
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•Calcium alginate/deacetylated konjac glucomannan (Ca-SA/DKGM) films were prepared.•Water sensitivity of the Ca-SA/DKGM films was reduced.•Surface hydrophobicity of the Ca-SA/DKGM films was improved.•Tensile properties of the Ca-SA/DKGM films were enhanced.
MXene, as a new 2-dimensional (2D) material, has excellently potential applications in the field of electrochemistry owing to its high conductivity and fast charge transporting speed. Especially, ...MXene/polymer composites have attracted widely attentions due to their extensive application in the area of multi-functional materials. Herein, the composites of Ti3C2Tx MXene/polyaniline (PANI) with different PANI contents have been successfully prepared. The microwave absorption mechanism of these materials was investigated. Attributing to the multiple layer structure, the dielectric property of Ti3C2Tx MXene and PANI, and the synergistic effect between the Ti3C2Tx and PANI, the as-prepared composites possessed a specific microwave absorbing behavior. With a proper content of PANI, the MXene/PANI composites in a paraffin matrix exhibited a maximum reflection loss of −56.30 dB at 13.80 GHz with the thickness of 1.8 mm. In addition, the effective absorption bandwidth (>90%) ranged from X-band (8–12.4 GHz) to Ku-band (12.4–18 GHz) with the tunable thickness ranging from 1.5 to 2.6 mm. The results indicate that MXene/PANI composites has great potential to be used in the field of microwave absorption.
Controlling interfacial microstructure and interactions between carbon fiber (CF) and matrix is of crucial importance for the fabrication of advanced polymer composites. In this paper, a hierarchical ...reinforcement (CF-g-SiO2) was prepared through directly grafting 3-aminopropyltriethoxysilane (APS) functionalized silica nanoparticles (SiO2-APS) onto CF surface by the covalent linkage for the first time. SiO2-APS nanoparticles distributed onto the fiber surface uniformly, which could increase surface polarity and roughness obviously. CF-g-SiO2 exhibited a low contact angle and high surface free energy, and thus enhanced the wettability between CF and matrix greatly. Simultaneous increases of interlaminar shear strength (ILSS) and interfacial shear strength (IFSS) of CF-g-SiO2 composites were achieved, increasing 53.27% in ILSS and 40.92% in IFSS compared with those of untreated composites. These enhancements can be attributed to the existent of SiO2-APS interface with providing sufficient chemical bonding and strong mechanical interlocking between the fiber and matrix. Moreover, impact resistance of CF-g-SiO2 composites was enhanced with increasing the amplitude of 34.95%. In addition, the introduction of Si-O-Si bonds at the interface by SiO2-APS grafting leads to the remarkable enhancement of the hydrothermal aging resistance.
Asphalt binder is a very important building material in infrastructure construction; it is commonly mixed with mineral aggregate and used to produce asphalt concrete. Owing to the large differences ...in physical and chemical properties between asphalt and aggregate, adhesive bonds play an important role in determining the performance of asphalt concrete. Although many types of adhesive bonding mechanisms have been proposed to explain the interaction forces between asphalt binder and mineral aggregate, few have been confirmed and characterized. In comparison with chemical interactions, physical adsorption has been considered to play a more important role in adhesive bonding between asphalt and mineral aggregate. In this study, the silicon tip of an atomic force microscope was used to represent silicate minerals in aggregate, and a nanoscale analysis of the characteristics of adhesive bonding between asphalt binder and the silicon tip was conducted via an atomic force microscopy (AFM) test and molecular dynamics (MD) simulations. The results of the measurements and simulations could help in better understanding of the bonding and debonding procedures in asphalt–aggregate mixtures during hot mixing and under traffic loading. MD simulations on a single molecule of a component of asphalt and monocrystalline silicon demonstrate that molecules with a higher atomic density and planar structure, such as three types of asphaltene molecules, can provide greater adhesive strength. However, regarding the real components of asphalt binder, both the MD simulations and AFM test indicate that the colloidal structural behavior of asphalt also has a large influence on the adhesion behavior between asphalt and silicon. A schematic model of the interaction between asphalt and silicon is presented, which can explain the effect of aging on the adhesion behavior of asphalt.
A facile route to hierarchically organized multicompartmentalized proteinosomes based on a recursive Pickering emulsion procedure using amphiphilic protein–polymer nanoconjugate building blocks is ...described. The number of incarcerated guest proteinosomes within a single host proteinosome is controlled, and enzymes and genetic polymers encapsulated within targeted subcompartments to produce chemically organized multi‐tiered structures. Three types of spatiotemporal response—retarded concomitant release, synchronous release or hierarchical release of dextran and DNA—are demonstrated based on the sequential response of the host and guest membranes to attack by protease, or through variations in the positioning of disulfide‐containing cross‐links in either the host or guest proteinosomes integrated into the nested architectures. Overall, our studies provide a step towards the construction of hierarchically structured synthetic protocells with chemically and spatially integrated proto‐organelles.
A hierarchical proteinosome architecture comprising three nested layers and different types of encapsulated components was fabricated (see picture). Engineering the cross‐links in the host and guest proteinosome membranes gave rise to three different types of programmed release behavior.
An effective method for bonding carbon nanotubes (CNTs) onto carbon fibers (CFs) surface via layer-by-layer (LBL) grafting method is reported here. The CNTs have been chemically grafted as confirmed ...by X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy (SEM) indicates that this LBL method can increase the dispersion quality of the CNTs on CF surface. The polarity, wettability and roughness of the CFs have been significantly increased after the CNTs modifying. The interfacial shear strength (IFSS) and impact strength test suggest that the hierarchical structure can result in a remarkable improvement for the interfacial properties. The results also indicate that this LBL method is a promising technique to modify CFs with the high interfacial performance.
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•A new growth method of TiO2 NWs on different CF surfaces was proposed.•Supercritical water is an availably medium to improve reaction efficiency.•Introducing HMTA or PEI on CF could ...increase significantly the adhesion strength between CF and TiO2 NWs and their interfacial shear strength with epoxy.•The tensile strength of carbon fiber does not decrease distinctly.
A novel amine-based functionalization method was developed to improve the interfacial adhesion between TiO2 NWs and CFs in supercritical water. The microstructure, morphology and mechanical properties of CFs were investigated. It was found that introducing hexamethylenetetramine (HMTA) dendrimers and branched polyethyleneimine (PEI) on CF could increase significantly the adhesion strength between CF and TiO2 NWs and their interfacial shear strength with epoxy resin, and the order is CF-PEI-TiO2 NWs>CF-HMTA-TiO2 NWs>CF-COOH-TiO2 NWs>CF-TiO2 NW. Meanwhile, the reinforcing mechanisms and interfacial failure modes have also been discussed. We believe that these effective methods may provide theoretical foundation for the preparation of high performance composite materials.
The electrochemical performance of nanostructured nickel-cobalt sulfides is greatly limited by the sluggish reaction kinetics and limited electroactive sites. Herein, we design and synthesize ...free-standing Se doped nickel-cobalt sulfides with controllable-component directly on carbon cloth, which involves the hydrothermal process and sulfuration/selenylation reaction. Serving as free-standing electrode, as-synthesized Se doped nickel-cobalt sulfides not only favor the fast ion diffusion path and low contact resistance, but also provide rich electroactive sites with electrolyte. More importantly, proper Se doping in nickel-cobalt sulfides greatly increases the electrochemically active surface area and reduces the charge transfer resistance. Based on the X-ray photoelectron spectroscopy and transmission electron microscopy results, the reaction mechanism is convincingly revealed that Se dopants have been changed into SeOx. And electrochemical activated oxyhydroxides are mainly involved in electrochemical reactions. As a result, as-fabricated Se doped nickel-cobalt sulfides show a good electrochemical performance for supercapattery. Further, the supercapattery device is also assembled by using nickel-cobalt sulfide/selenide as positive electrode and activated carbon as negative electrode, which shows a high energy density of 39.6 Wh kg−1 at the power density of 1501 W kg−1.
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•Se doping can provide large the active sites and fast electron transport path.•The Se doped nickel-cobalt sulfides show good electrochemical performances.•The NiCo2S2.2Se1.8//AC device shows a high energy density of 39.6 Wh kg−1.
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