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Insights into the Intrinsic Factors Affecting the NIR Reflectance Based on Rylene Diimide Molecules
No full textA clear understanding of the relationships between molecular structure and NIR reflectance (700-2500 nm) behavior is important and highly desirable for developing appropriate NIR-reflective materials to combat NIR heat radiation from sunlight. In this research, three groups of imide-based compounds have been adopted to investigate the influence of the intrinsic molecular structures on the NIR-reflective properties. It is found out that for the compounds with alkyl groups, the NIR reflectance will increase as the degree of the conjugated backbone increases, especially for the reflectance from 1750 nm to 2500 nm. In addition, despite that the alkyl or amine groups deteriorate the NIR reflectance, the NIR reflectance varies within a certain interval and the isomers with branched alkyl groups show identical or smaller NIR reflectance than those of isomers with linear alkyl groups. For different compounds, crystallinity seems to almost have no relationship with their NIR reflectance
Study on 3D-Direct Ink Writing based on adding silica submicron-particles to improve the rheological properties of alumina ceramic ink
No full textIn this report, alumina-silica composite ceramic is manufactured by using the 3D-Direct Ink Writing (DIW) printing technology based on additive manufacturing. In order to improve the compactness and mechanical properties of the alumina ceramics, the silica submicron-particles are introduced as sintering aids and fillers. However, no research has focused on the effect of adding silica submicron-particles on the alumina ceramic manufactured by 3D-DIW. Due to the addition of silica submicron-particles, the upper limit of alumina solids in 3D-DIW ink is increased. Then the effect of silica submicron-particles on the rheological behavior of 3D-DIW ink was studied. In the linear viscoelastic region, the ink with high-solid (75 wt%) with elastic modulus of about 7.5 x 10(5) Pa is the best concentration for 3D-DIW. High-solid ink was used to manufacture 3D alumina-silica composite ceramic parts, and a series of testing methods were used to examine the related properties after sintering at 1600 degrees C, including volume shrinkage, microstructure and compressive strength
Aggregation-Induced Emissive Carbon Dots Gels for Octopus-Inspired Shape/Color Synergistically Adjustable Actuators
No full textSome living organisms such as the octopus have fantastic abilities to simultaneously swim away and alter body color/morphology for disguise and self-protection, especially when there is a threat perception. However, it is still quite challenging to construct artificial soft actuators with octopus-like synergistic shape/color change and directional locomotion behaviors, but such systems could enhance the functions of soft robotics dramatically. Herein, we proposed to utilize unique hydrophobic carbon dots (CDs) with rotatable surficial groups to construct the aggregation-induced emission (AIE) active glycol CDs polymer gel, which could be further employed to be interfacially bonded to an elastomer to produce anisotropic bilayer soft actuator. When putting the actuator on a water surface, glycol spontaneously diffused out from the gel layer to allow water intake, resulting in a color change from a blue dispersion fluorescence to red AIE and a shape deformation, as well as a large surface tension gradient that can promote its autonomous locomotion. Based on these findings, artificial soft swimming robots with octopus-like synergistic shape/color change and directional swimming motion were demonstrated. This study provides an elegant strategy to develop advanced multi-functional bio-inspired intelligent soft robotics
Facile synthesis of metal and alloy nanoparticles by ultrasound-assisted dealloying of metallic glasses
No full textMetal and alloy nanoparticles synthesized by chemical reduction have attracted increasing attention due to their superior physical, chemical, and biological properties. However, most chemical synthesis processes rely on the use of harsh reducing agents and complicated chemical ingredients. Herein, we report a novel reduction-agent-free and surfactant (stabilizer)-free strategy to synthesize Cu, Ag, Au, Cu-Pt, Cu-Au, Cu-Au-Pt-Pd, and Au-Pt-Pd-Cu nanoparticles by ultrasound-assisted dealloying of Mgbased metallic glasses. The formation mechanism of the metal and alloy nanoparticles is revealed by a detailed investigation of sequential intermediate products. We demonstrate that the glass-liquid phase transition of the initially dealloying metallic glasses, together with the synergistic effect of dealloying and ultrasound-driven ligament-breakage of small enough nanoporous intermediates, play key roles in preparing the uniformly dispersed metal and alloy nanoparticles. This approach greatly simplifies the up-scaling synthesis of monometallic and bimetallic nanoparticles, and also provides a general strategy for synthesizing unprecedented multimetallic nanoparticles. (C) 2021 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology
Fabrication of Porous Aluminum Coating by Cored Wire Arc Spray for Anchoring Antifouling Hydrogel Layer
No full textBiofouling has been persisting as a worldwide problem due to the difficulties in finding efficient environment-friendly antifouling coatings for long-term applications. Developing novel coatings with desired antifouling properties has been one of the research goals for surface coating community. Recently hydrogel coating was proposed to serve as antifouling layer, for it offers the advantages of the ease of incorporating green biocides, and resisting attachment of microorganisms by its soft surface. Yet poor adhesion of the hydrogel on steel surfaces is a big concern. In this study, porous matrix aluminum coatings were fabricated by cored wire arc spray, and the sizes of the pores in the aluminum (Al) coatings were controlled by altering the size of the cored powder of sodium chloride. Silicone hydrogel was further deposited on the porous coating. The hydrogel penetrated into the open pores of the porous Al coatings, and the porous Al structure significantly enhanced the adhesion of the hydrogel. In addition, hydrogel coating exhibited very encouraging antifouling properties
Proximity-Induced Novel Ferromagnetism Accompanied with Resolute Metallicity in NdNiO3 Heterostructure
No full textEmploying X-ray magnetic circular dichroism (XMCD), angle-resolved photoemission spectroscopy (ARPES), and momentum-resolved density fluctuation (MRDF) theory, the magnetic and electronic properties of ultrathin NdNiO3 (NNO) film in proximity to ferromagnetic (FM) La0.67Sr0.33MnO3 (LSMO) layer are investigated. The experimental data shows the direct magnetic coupling between the nickelate film and the manganite layer which causes an unusual ferromagnetic (FM) phase in NNO. Moreover, it is shown the metal-insulator transition in the NNO layer, identified by an abrupt suppression of ARPES spectral weight near the Fermi level (E-F), is absent. This observation suggests that the insulating AFM ground state is quenched in proximity to the FM layer. Combining the experimental data (XMCD and AREPS) with the momentum-resolved density fluctuation calculation (MRDF) reveals a direct link between the MIT and the magnetic orders in NNO systems. This work demonstrates that the proximity layer order can be broadly used to modify physical properties and enrich the phase diagram of RENiO3 (RE = rare-earth element)
Double-Layer Nitrogen-Rich Two-Dimensional Anionic Uranyl-Organic Framework for Cation Dye Capture and Catalytic Fixation of Carbon Dioxide
No full textA novel two-dimensional double-layer anionic uranyl-organic framework, U-TBPCA {[NH2(CH3)(2)][(UO2)(TBPCA)], where H(3)TBPCA = 4,4',4-s-triazine-1,3,5-triyltripamino-methylene-cyclohexane-carboxylate}, with abundant active sites and stability was obtained by assembling UO2(NO3)(2). 6H(2)O and a triazine tricarboxylate linker, TBPCA(3-). Due to the flexibility of the ligand and diverse coordination modes between carboxyl groups and uranyl ions, U-TBPCA exhibits an intriguing topological structure and steric configuration. This double-layer anionic uranyl-organic framework is highly porous and can be used for selective adsorption of cationic dyes. Due to the presence of high-density metal ions and basic -NH- groups, U-TBPCA acts as an effective heterogeneous catalyst for the cycloaddition reaction of carbon dioxide with epoxy compounds. Moreover, the various modes of coordination between the tricarboxylic ligand and uranyl ion were studied by density functional theory calculations, and several simplified models were established to probe the influence of hydrogen bonding between carbon dioxide and U-TBPCA on the ability of U-TBPCA to bind carbon dioxide. This work should aid in improving our understanding of the coordination behavior of uranyl ion as well as the development and utilization of new actinide materials
A fully hydrophobic ionogel enables highly efficient wearable underwater sensors and communicators
No full textUnderwater sensing has extraordinary significance in ocean exploration (e.g., marine resources development, marine biology research, and marine environment reconnaissance), but the great difference between the marine environment and the land environment seriously prevents current traditional sensors from being applied in underwater sensing. Herein, we reported a fully hydrophobic ionogel with long-term underwater adhesion and stability as a highly efficient wearable underwater sensor that displays an excellent sensing performance, including high sensitivity, rapid responsiveness and superior durability. Of greater significance, the ionogel sensor showed tremendous potential in underwater sensing applications for communication, posture monitoring and marine biological research
Super-anticorrosive inverse nacre-like graphene-epoxy composite coating
No full textGraphene-based coatings (GCs) have emerged as attractive candidates for engineering applications. Despite recent progresses, efforts to achieve high-performance and durable GCs through conventional blending have been frustrated due to the uncontrolled distribution and orientation of graphene nanosheets, which degrades anticorrosion properties. By mimicking the nacre's microstructure, here we successfully fabricated a bioinspired GC, in which graphene nanosheets self-assembly in smectic can order in the epoxy matrix. As the bioinspired coating (similar to 98 wt% of epoxy polymer) shows an inverse composition to nacre (similar to 96 wt% of aragonite nanoplatelets), thus which is called an ``inverse nacre-like'' coating. The resultant bioinspired coating has high compactness and alignment degree, resulting in greatly enhanced physical barrier property and anticorrosion performance. Electrochemical tests reveal that the impedance modulus is 3 orders of magnitude much higher than that of blank coating. More importantly, the bioinspired coating shows a highly anisotropic conductivity due to the anisotropic graphene layers, preventing local galvanic corrosion through eliminating the current leakage in the outof-plane direction. (C) 2021 Elsevier Ltd. All rights reserved
Nano dual-phase CuNiTiNbCr high entropy alloy films produced by high-power pulsed magnetron sputtering
No full textDual-phase high entropy alloys have been proved to have the ability to overcome the strength-ductility trade-off. However, high-entropy alloy films are difficult to obtain a dual-phase structure due to the extremely high cooling rate during the preparation process and the high-entropy effect of the film itself. In this paper, the dual-phase CuNiTiNbCr high-entropy alloy films were prepared by high-power pulsed magnetron sputtering at different working pressures. The composition, microstructures, mechanical properties and electrochemical corrosion performance were tested by energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), nano-indentation, Vickers indentation and electrochemical polarization. The CuNiTiNbCr films exhibited a dual-phase structure composed of FCC matrix phase and Cu-rich BCC precipitated phase. The film presented a two-layer structure, the single FCC phase structure near the substrate and the FCC + BCC structure above. Comparing with FCC phase, the dual-phase structure exhibited higher hardness. With the increase of deposition pressure, the structure of the film became looser, and the hardness, toughness and corrosion resistance were all decreased due to the influence of the structure. It is proved that high-power pulsed magnetron sputtering is a feasible way for the phase structure regulation and performance improvement of high-entropy alloy films