XPS Investigation of the Oxidation States of the As-Deposited Ta Films Prepared by Magnetron Sputtering Technology.

Due to their versatile and unique properties, tantalum-based thin films have been extensively studied. However, tantalum is susceptible to oxidation due to its higher chemical activity, which is crucial regardless of whether oxidations of Ta are beneficial or detrimental. Therefore, the oxidation of Ta during material processing, especially without conscious means, should be taken seriously. In this study, pure Ta films were fabricated by magnetron sputtering under set procedure parameters. The effects of base pressure and substrate temperature on the degree of oxidation of Ta films were investigated. The results revealed that the magnitude of the base pressure directly affects the oxidation state of the as-deposited Ta films. When preferably avoiding the oxidation of sputtered Ta films, the base pressure should be controlled below 4.4 × 10-4 Pa. The substrate temperature has little effect on the oxidation state of the as-deposited Ta films under a base pressure ranging from about 10-2 Pa to 10-4. We hope that this study can provide some references for controlling the oxidation states of Ta involved in relevant film preparation.

Ammonia Adsorption Performance of Zeolitic Imidazolate Frameworks for Cooling.

Promoting the cooling performance of adsorption chillers (ACs) greatly relies on the exploration of high-performance adsorbent/refrigerant working pairs. Ammonia is not only an environmentally friendly refrigerant but also favorable for heat and mass transfer in ACs owing to its large vapor pressure and enthalpy of evaporation. Zeolite imidazolate frameworks (ZIFs) with excellent ammonia stability are identified as a class of potential adsorbents for practical ammonia-based ACs. However, high-performing ZIF/ammonia working pairs with excellent AC performance are still to be developed. In this work, the cooling performance including the coefficient of performance for cooling (COPC) and the specific cooling effects (SCEs) of 26 ZIFs with the same composites but different topologies was evaluated by combining molecular simulation and mathematical modeling. Five high-performing ZIFs with COPC > 0.45 and SCE > 250 kJ/kg were identified, among which gis-ZIF with the highest COPC of 0.51 and lta-ZIF with the highest SCE of 354 kJ/kg both are promising to be synthesized and applied further. Besides, the quantitative structure-performance relationship (QSPR) was extracted that can help quickly identify and design high-performing ZIFs according to their ammonia adsorption isotherms and structural characteristics. Moreover, "S"-shaped adsorption isotherms with high saturation adsorption capacity (>0.2 g/g), suitable step position (0.2-0.4), and relatively low Henry's constant (<1 × 10-5 mol/(kg·Pa)) are more favorable for excellent COPC and SCE. From the perspective of structure characteristics, ZIFs possessing low crystal density (<0.9 g/cm3), high accessible surface area (>2000 m2/g), balanced largest cavity diameter (∼15 Å), and accessible pore volume (∼0.65 cm3/g) are beneficial for high-efficient cooling performance.

Metal-Organic Frameworks for Ammonia-Based Thermal Energy Storage.

Recently, the application of metal-organic frameworks (MOFs) in thermal energy storage has attracted increasing research interests. MOF-ammonia working pairs have been proposed for controlling/sensing the air quality, while no work has yet been reported on the immense potential of MOFs for thermal energy storage up till now. Herein, the feasibility of thermal energy storage using seven MOF-ammonia working pairs is experimentally assessed. From ammonia sorption stability and sorption thermodynamics results, it is found that MIL-101(Cr) exhibits both high ammonia sorption stability and the largest sorption capacity of ≈0.76 g g-1 . Compared with MIL-101(Cr)-water working pair, MIL-101(Cr)-ammonia working pair improves the sorption capacity by over three times with evaporation temperature lower than 8.4 °C. Due to stable ammonia sorption stability and negligible hysteresis, MIL-101(Cr) and ZIF-8(Zn) are tested at condensation/evaporation temperature of 30 °C/10 °C. The thermal energy storage density (reaching over 1200 kJ kg-1 ) and coefficient of performance of MIL-101(Cr)-based system are both higher than ZIF-8(Zn)-based one due to larger average isosteric enthalpy and cycle sorption capacity. This experimental work paves the way for developing the high efficient and stable thermal energy storage system with MOF-ammonia working pairs especially for critical conditions with low evaporation temperature and high condensation temperature.

Embedded polyzwitterionic brush-modified nanofibrous membrane through subsurface-initiated polymerization for highly efficient and durable oil/water separation.

HYPOTHESIS: Developing separation membranes functionalized by polymer brushes with high separation efficiency and good cycling stability is of great importance for oil/water separation, yet is still challenged. EXPERIMENTS: In this work, the covalently embedded polyzwitterionic brush-functionalized nanofibrous membrane was developed for efficient and durable oil/water separation. The nanofibrous membrane was prepared by the electrospinning method using initiator-embedded polyacrylonitrile (PAN) resin, followed by novel subsurface-initiated atom transfer radical polymerization (SSI-ATRP) to graft embedded poly(sulfobetaine methacrylate) brushes (PSBMA). The hydration ability, underwater oil adhesion, oil/water separation performance as well as self-cleaning properties of the as prepared membrane (PAN-sg-PSBMA) were systematically studied. FINDINGS: The PAN-sg-PSBMA membrane exhibited extraordinary hydration ability and underwater superoleophobicity with extremely low oil adhesion, which outperformed conventional polymer brush-modified membrane (PAN-g-PSBMA). The PAN-sg-PSBMA membrane was able to separate both oil/water mixture and surfactant-stabilized emulsions with ultrahigh permeation flux and separation efficiency. Moreover, compared with PAN-g-PSBMA, PAN-sg-PSBMA membrane exhibited unprecedented recycling stability in both permeation flux and separation efficiency, which is attributed to mechanical robustness of embedded polymer brushes and outstanding antifouling ability. The current findings revealed that embedded polymer brushes from SSI-ATRP could offer a promising design of functionalized nanofibrous membrane for highly efficient and durable oil/water separation.

3D Printing of an Oil/Water Mixture Separator with In Situ Demulsification and Separation.

Currently, many meshes, membranes, and fabrics with extreme wettability of superhydrophobicity/superoleophilicity, or superhydrophilicity and underwater superoleophobicity are promising candidates for oil/water mixture separation. Nevertheless, a facile yet effective way to design and fabricate porous mesh still remains challenging. In this work, fused deposition modeling (FDM) 3D printing of Fe/polylactic acid (PLA) composites was employed to fabricate superhydrophilic and underwater superoleophobic mesh (S-USM) with hydrogel coatings via the surface polymerization of Fe(II)-mediated redox reaction. In addition, salt of aluminum chloride was incorporated within the hydrogel coating, which was attributed to strengthening the demulsification of oil-in-water emulsions, resulting in efficient separation of oil-in-water mixtures. The S-USM was efficient for a wide range of oil-in-water mixtures, such as dodecane, diesel, vegetable oil, and even crude oil, with a separation efficiency of up to 85%. In this study, the flexible design and fabrication of 3D printing were used for the facile creation of spherical oil skimmers with hydrogel coatings that were capable of removing the floating oil. Most importantly, this work is expected to promote post-treatment processes using 3D printing as a new manufacturing technology and, in this way, a series of devices of specific shape and function will be expanded to satisfy desired requirements and bring great convenience to personal life.

Post-treatment Method for the Synthesis of Monodisperse Binary FePt-Fe3O4 Nanoparticles.

To obtain the optimal 1:1 composition of FePt alloy nanomaterials by polyol synthesis, the iron precursor (iron pentacarbonyl, Fe(CO)5) must be used in excess, because the Fe(CO)5 exists in the vapor phase at the typical temperatures used for FePt synthesis and cannot be consumed completely. Fabrication of Fe3O4 nanoparticles by consuming the excess iron precursor was an effective strategy to make full use of the iron precursor. In this paper, a facile post-treatment method was applied to consume the excess iron, which was oxidized to Fe3O4 after post-treatment at 150 and 200 °C, and a monodisperse binary FePt-Fe3O4 nanoparticle system was generated. The post-treatment method did not affect the crystal structure, grain size, or composition of the FePt nanoparticles. However, the content and grain size of the fcc-Fe3O4 nanoparticles can be increased simply by increasing the post-treatment temperature from 150 to 200 °C.

Surface engineering for an enhanced photoelectrochemical response of TiO2 nanotube arrays by simple surface air plasma treatment.

A simple method to improve the photoelectrochemical performance of TiO2 nanotube arrays (NTs) by simple air plasma post-treatment is reported. The air plasma treated sample shows higher photocurrent density and incident photo current efficiency with high stability, about 3-4 times that of the pristine TiO2 NTs even after six months.

One-step modification of fabrics with bioinspired polydopamine@octadecylamine nanocapsules for robust and healable self-cleaning performance.

An in-situ polymerization to coat fabrics with polydopamine-encapsulated octadecylamine endows the fabrics with self-cleaning and self-healing abilities. The treated fabric exhibits self-healing after losing its hydrophobicity. It is durable against washing and mechanical abrasion without changing the hydrophobicity. Thanks to the versatile adhesive property of polydopamine, the approach is compatibile with a variety of substrates, such as fabrics, glass, sponge, paper, and polymeric materials.

Hairy polyelectrolyte brushes-grafted thermosensitive microgels as artificial synovial fluid for simultaneous biomimetic lubrication and arthritis treatment.

We report the fabrication of poly(3-sulfopropyl methacrylate potassium salt) (PSPMK) brushes grafted poly(N-isopropylacrylamide) (PNIPAAm) microgels and their potential as artificial synovial fluid for biomimetic aqueous lubrication and arthritis treatment. The negatively charged PSPMK brushes and thermosensitive PNIPAAm microgels play water-based hydration lubrication and temperature-triggered drug release, respectively. Under soft friction pairs, an ultralow coefficient of friction was achieved, while the hairy thermosensitive microgels showed a desirable temperature-triggered drugs release performance. Such a soft charged hairy microgel offers great possibility for designing intelligent synovial fluid. What is more, the combination of lubrication and drug loading capabilities enables the large clinical potential of novel soft hairy nanoparticles as synthetic joint lubricant fluid in arthritis treatment.

Photoresponsive superhydrophobic coating for regulating boundary slippage.

A photoresponsive copolymer containing catechol and azobenzene derivatives was synthesized. The copolymer easily attached onto various substrates and showed a photoresponsive characteristic because of its catechol and azobenzene functional groups. The copolymer was successfully assembled on nanoparticles, plate mica, and rough anodized aluminum surface. The rough anodized aluminum sheet retained the Cassie-Baxter state after being modified with the copolymer. Moreover, surface adhesion can be interchanged by changing the UV exposure time. The sliding and adhesive states of water droplets were achieved by UV exposure and dark storage. Boundary slip on the rough sheet was measured using a commercial rheometer, and interchangeable slip length was also obtained after irradiation or storage. The versatile, substrate-independent approach may be significant in the development of new materials for smart fluid devices.

Switching fluid slippage on pH-responsive superhydrophobic surfaces.

Two stimuli-responsive polymer brushes, poly(dimethylaminoethyl methacrylate) and poly(methacrylic acid), were grafted from initiator-modified anodized alumina substrates to prepare two pH-responsive surfaces. By regulating the swelling states of the two polymers, water droplets can roll off or adhere onto the textured surface because of different adhesion forces. These forces also strongly affect boundary slippage. To determine the different slippage effects of fluid on our pH-responsive surfaces, a series of rheological experiments are carried out on two kinds of surfaces. A large slip length is obtained and reversibly regulated by changing the fluid pH. These responsive superhydrophobic surfaces with considerable slip length and pH-responsive properties have extensive potential applications in intelligent micro- and nanofluidic devices or biodevices, which can solve fluid flow problems.

Three-dimensional compressible and stretchable conductive composites.

Three-dimensional (3D) conductive composites with remarkable flexibility, compressibility, and stretchability are fabricated by solution deposition of thin metal coatings on chemically modified, macroscopically continuous, 3D polyurethane sponges, followed by infiltration of the metallic sponges with polydimethylsiloxane (PDMS). These low-cost conductive composites are used as high-performance interconnects for flexible and stretchable light-emitting diode (LED) arrays, even with severe surface abrasion or cutting.

Matrix-assisted catalytic printing for the fabrication of multiscale, flexible, foldable, and stretchable metal conductors.

Matrix-assisted catalytic printing (MACP) is developed as a low-cost and versatile printing method for the fabrication of multiscale metal conductors on a wide variety of plastic, elastomeric, and textile substrates. Highly conductive Cu interconnects (2.0 × 108 S/m) fabricated by MACP at room temperature display excellent flexibility, foldability, and stretchability.

High-resolution, large-area, serial fabrication of 3D polymer brush structures by parallel dip-pen nanodisplacement lithography.

Parallel dip-pen nanodisplacement lithography (p-DNL) is used for high resolution, serial fabrication of 3D structures of polymer brushes over millimeter length scales. With p-DNL, 2D initiator templates consisting of arrays of nanolines and nanodots with rationally designed lateral spacings are fabricated in parallel via a locally tip-induced nanodisplacement process, from which highly defined 3D polymer structures are grown via surface-initiated atom transfer radical polymerization.

2-Amino-9-[(1S,3R,4S)-4-hydr-oxy-3-hydroxy-methyl-2-methyl-enecyclo-pent-yl]-1,9-dihydro-6H-purin-6-one monohydrate.

In the crystal of the title compound, C(12)H(15)N(5)O(3)·H(2)O, the component species are linked by N-H⋯N, N-H⋯O, O-H⋯N and O-H⋯O hydrogen bonds, forming a three-dimesnional network.

Poly[[aqua-(µ-4,4'-bipyridyl-κN:N')bis-(µ-formato-κO:O')iron(II)] tetra-hydrate].

In the title compound, {[Fe(CHO(2))(2)(C(10)H(8)N(2))(H(2)O)]·4H(2)O}(n), the Fe(II) ion is coordinated by two 4,4'-bipyridyl (4,4'-bpy) ligands, three formate ligands and one water molecule. The slightly distorted octahedral FeN(2)O(4) coordination results from the N atoms of two bridging 4,4'-bpy ligands, the O atoms of two bridging HCOO(-) anions of anti-anti mode, all in trans positions around the metal centre, and the O atoms of one terminal HCOO(-) anion and of one water molecule. The bridging formate ligands link the metal ions into chains that are further connected via 4,4'-bpy ligands into a framework structure. The three-dimensional structure is stabilized by extensive O-H⋯O hydrogen bonding. The crystals were twinned containing a 0.84:0.16 racemate.

catena-Poly[[[[3-(2-pyrid-yl)-1H-pyra-zole]nickel(II)]-µ-oxalato] sesquihydrate].

In the title compound, {[Ni(C(2)O(4))(C(8)H(7)N(3))]·1.5H(2)O}(n), both unique Ni(II) ions are chelated by an O,O'-bidentate oxalate ion and an N,N'-bidentate 3-(2-pyrid-yl)pyrazole mol-ecule. A second, symmetry-generated, oxalate ion completes a distorted cis-NiN(2)O(4) octa-hedral geometry for both metal centres. The bridging oxalate ions result in two distinct wave-like polymeric chains propagating in [100]. The packing is consolidated by N-H⋯O and O-H⋯O hydrogen bonds. The crystal studied was found to be an inversion twin.

Reversible hydration and dehydration of polyanionic brushes bearing carboxylate, phosphate and sulfonate side groups: a comparative AFM study.

The present work reports on a systematic study of the swelling/collapse transition of three anionic polymer brushes bearing carboxylate, phosphate and sulfonate side groups via AFM measurement. Time scale of conformation change process can be approximately evaluated directly. All the three brushes in their sodium salt forms stretch away from the surface in pure water, as a result of charge repulsion and uptake of water. The collapse of weak brushes has two ways: normal charge screening and precipitation (strong ion pairing), depending on the types of cations that have different coordination capabilities with anionic groups. Alkali metal ions can make brushes shrink only at relatively high concentrations following a gradually increased charge screening mechanism. The brushes collapsed in this way can be restored by simply flushing with water. However, multivalent cations can irreversibly collapse brushes more easily even under very low concentrations (<10(-3) mol L(-1)). The brushes cannot be restored with simple water rinsing even for strong sulfonate containing brushes. In this case, recovery can be achieved by ion exchange in concentrated salt solution, which facilitates transit from strong ion pairing to less strong charge screening and then flushing with water. Alternatively, the multivalent ion can be extracted with chelating reagent of low concentration (10 mM EDTA). As the chelating agent doesn't affect the conformation of brushes, the brushes are one-step recovered directly, much more efficient than with high concentration electrolyte which usually requires extra water rinsing to remove excess salt inside brushes. The interaction between anions in the brushes and metal ions represents a model system to profoundly understand the mechanism of bio-mimic motions and how muscle works. In this regard, the present study provides useful information for the development of polyelectrolyte brushes based ion sensor and ion powered nanoactuators.