Superhydrophobic nanocomposite coatings with photoinitiated three-dimensional networks based on reactive graphene nanosheet-induced self-wrinkling patterned surfaces.

HYPOTHESIS: Bionic superhydrophobicity including high contact angle, low sliding angle and nonstick property, combined with both strong pH and ultraviolet (UV) resistance, is difficult to simultaneously achieve for large-scale preparation of superhydrophobic surfaces by blending polymer with a nonreactive inorganic nanofiller. EXPERIMENTS: A series of high pH and UV-irradiation-resistant superhydrophobic nanocomposite films were prepared through UV-light-assisted chemical cross-linking among ternary components under nitrogen protection. Ethoxylated bisphenol A diacrylate, 2-(perfluorooctyl) ethyl acrylate, reactive thiol-coupled graphene nanosheets and photoinitiator were evenly mixed, followed by UV-irradiation curing. FINDINGS: Abundant 3D networks could be formed. A robust self-wrinkling surface morphology was formed due to a UV-curing-induced inner tension in the composites, 2D morphology-induced flexibility for graphene nanosheets and fluorine-bearing component-induced phase separation at the wetted surfaces. High roughness and use of the fluorine element endows the surfaces with superhydrophobicity and oleophobicity. A favorable nonstick performance was obtained. Superhydrophobicity could be maintained despite changing the film-forming substrate, pH of soaking solutions from 1 to 12, or use of a prolonged UV-irradiation time reaching 120 h. Therefore, both superhydrophobicity/oleophobicity and strong pH/UV resistance are finely balanced. This work might open up the way for large-scale fabrication of promising superhydrophobic surfaces.

Design and synthesis of hierarchical NiO/Ni3V2O8 nanoplatelet arrays with enhanced lithium storage properties.

Hierarchical NiO/Ni3V2O8 nanoplatelet arrays (NPAs) grown on Ti foil were prepared as free-standing anodes for Li-ion batteries (LIBs) via a simple one-step hydrothermal approach followed by thermal treatment to enhance Li storage performance. Compared to the bare NiO, the fabricated NiO/Ni3V2O8 NPAs exhibited significantly enhanced electrochemical performances with superior discharge capacity (1169.3 mA h g-1 at 200 mA g-1), excellent cycling stability (570.1 mA h g-1 after 600 cycles at current density of 1000 mA g-1) and remarkable rate capability (427.5 mA h g-1 even at rate of 8000 mA g-1). The excellent electrochemical performances of the NiO/Ni3V2O8 NPAs were mainly attributed to their unique composition and hierarchical structural features, which not only could offer fast Li+ diffusion, high surface area and good electrolyte penetration, but also could withstand the volume change. The ex situ XRD analysis revealed that the charge/discharge mechanism of the NiO/Ni3V2O8 NPAs included conversion and intercalation reaction. Such NiO/Ni3V2O8 NPAs manifest great potential as anode materials for LIBs with the advantages of a facile, low-cost approach and outstanding electrochemical performances.

Annealing and Stretching Induced High Energy Storage Properties in All-Organic Composite Dielectric Films.

High discharged energy density and charge⁻discharge efficiency, in combination with high electric breakdown strength, maximum electric displacement and low residual displacement, are very difficult to simultaneously achieve in single-component polymer dielectrics. Plenty of researches have reported polymer based composite dielectrics filled with inorganic fillers, through complex surface modification of inorganic fillers to improve interface compatibility. In this work, a novel strategy of introducing environmentally-friendly biological polyester into fluoropolymer matrix has been presented to prepare all-organic polymer composites with desirable high energy storage properties by solution cast process (followed by annealing or stretching post-treatment), in order to simplify the preparation steps and lower the cost. Fluoropolymer with substantial ferroelectric domains (contributing to high dielectric response) as matrix and poly (3-hydroxybutyrate-co-3-hydroxyvalerate) with excellent linear polarization property (resulting in high breakdown strength) as filler were employed. By high-temperature annealing, the size of ferroelectric domains could be improved and interfacial air defects could be removed, leading to elevated high energy storage density and efficiency in composite. By mono-directional stretching, the ferroelectric domains and polyester could be regularly oriented along stretching direction, resulting in desired high energy storage performances as well. Besides, linear dielectric components could contribute to high efficiency from their strong rigidity restrain effect on ferroelectric component. This work might open up the way for a facile fabrication of promising all-organic composite dielectric films with high energy storage properties.

Photoluminescent Ti3 C2 MXene Quantum Dots for Multicolor Cellular Imaging.

The fabrication of photoluminescent Ti3 C2 MXene quantum dots (MQDs) by a facile hydrothermal method is reported, which may greatly extend the applications of MXene-based materials. Interestingly, the as-prepared MQDs show excitation-dependent photoluminescence spectra with quantum yields of up to ≈10% due to strong quantum confinement. The applications of MQDs as biocompatible multicolor cellular imaging probes and zinc ion sensors are demonstrated.

Cytocompatibility of Ti3AlC2, Ti3SiC2, and Ti2AlN: In Vitro Tests and First-Principles Calculations.

Herein, the cytocompatibility of selected MAX phases, Ti3AlC2, Ti3SiC2, and Ti2AlN, were systematically evaluated using in vitro tests for the first time. These phases were anoxic to preosteoblasts and fibroblasts. Compared with the strong viable fibroblasts, the different cellular responses of these materials were clearly distinguishable for the preosteoblasts. Under an osteoblastic environment, Ti2AlN exhibited better cell proliferation and differentiation performance than Ti3AlC2 and Ti3SiC2. Moreover, the performance was superior to that of a commercial Ti-6Al-4V alloy and comparable to that of pure Ti. A possible mechanism was suggested based on the different surface oxidation products, which were determined from the binding energy of adsorbed Ca2+ ions using first-principles calculations. Compared with the partially oxidized TiCxOy layer on Ti3AlC2 and Ti3SiC2, the partially oxidized TiNxOy layer on the Ti2AlN had a stronger affinity to the Ca2+ ions, which indicated the good cytocompatibility of Ti2AlN.

Loading Actinides in Multilayered Structures for Nuclear Waste Treatment: The First Case Study of Uranium Capture with Vanadium Carbide MXene.

Efficient nuclear waste treatment and environmental management are important hurdles that need to be overcome if nuclear energy is to become more widely used. Herein, we demonstrate the first case of using two-dimensional (2D) multilayered V2CTx nanosheets prepared by HF etching of V2AlC to remove actinides from aqueous solutions. The V2CTx material is found to be a highly efficient uranium (U(VI)) sorbent, evidenced by a high uptake capacity of 174 mg g(-1), fast sorption kinetics, and desirable selectivity. Fitting of the sorption isotherm indicated that the sorption followed a heterogeneous adsorption model, most probably due to the presence of heterogeneous adsorption sites. Density functional theory calculations, in combination with X-ray absorption fine structure characterizations, suggest that the uranyl ions prefer to coordinate with hydroxyl groups bonded to the V-sites of the nanosheets via forming bidentate inner-sphere complexes.

[Strength of bi-layer dental ceramic evaluated by MSP testing].

OBJECTIVE: To evaluate strength of bi-layer alumina/Y-TZP specimens, compared with 3-point bending test and to estimate the reliability of MSP testing used in dental ceramics. METHODS: The single-layer/bi-layer alumina/Y-TZP specimens were produced by the clinical methods. Strength of these specimens was determined by MSP testing and 3-point bending test respectively. Fractured pieces of each bi-layer specimen were collected and studied with optical microscope and SEM. RESULTS: The MSP fracture strength was lower than bending strength in all the specimens. The strength of single-layer Y-TZP was the highest and the strength of bi-layer samples was lower than that of the single-layer samples respectively. Delamination and interface destruction were found in bi-layer alumina specimens, and not in bi-layer Y-TZP specimens. CONCLUSION: MSP testing is a convenient and feasible method to evaluate mechanical properties of dental ceramics.