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Layered double hydroxides (LDHs) can serve as corrosion inhibitor reservoirs. In the present work, hydrotalcite-like LDHs were synthesized and employed as host matrixes for the release of phosphate. The morphological and structural properties of the as-prepared LDH-PO4 were characterised by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The PO43- adsorption uptake was successfully confirmed by the XRD results. The corrosion resistance of the coating with LDH-PO4 was investigated by electrochemical impedance spectroscopy (EIS), which was approximately 1 order of magnitude higher than that of the blank coating after immersion for 168 h. Results of the scanning Kelvin probe technique revealed that the potential of LDH-PO4 coating was higher and smoother than that of the blank coating after exposure to 0.5 M NaCl solution. This effect is attributed to the release of PO43− that forms a phosphate protective film in the scratched region. [ABSTRACT FROM AUTHOR]

Polyurethane (PU) and polyurea (PUA) materials have shown significant potential for application in tissue repair. Herein, we design a glycerol ethoxylate (PEG)-based poly(urethane-urea) for bone tissue repair. The polymer precursor was prepared from the reaction of PEG and isophorone diisocyanate (IPDI). The cystine dimethyl ester was used as a cross-linker for the preparation of poly(urethane-urea) elastomers. The material was further strengthened by physical blending of nano-hydroxyapatite (nHA). The physical and biological properties of final material were evaluated by mechanical testing, scanning electron microscopy characterization, degradation tests, cell proliferation and cell differentiation assays. The obtained scaffolds showed good mechanical strength, excellent biocompatibility and osteogenic capability. All the evidences demonstrated that this type of materials has good prospects for bone tissue repair application. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) film was prepared on silicon () substrate with a 3-aminopropyltriethoxysilane (APTES) film as the interlayer in a multistep self-assembly process. The formation and microstructure of the CNTs film were characterized by using scanning electron microscopy (SEM), water contact angles (WCAs) and X-ray photoelectron spectrometry (XPS). Tribological properties were evaluated with a UMT-2MT reciprocating friction tester. Results show that the CNTs were successfully assembled on substrates by chemical bonding between functional groups. CNTs film exhibited excellent friction reduction, high load-bearing capacity and antiwear ability. The friction coefficient was reduced drastically from 0.7 to 0.16, with markedly prolonged antiwear lifetime compared to bare substrates or APTES film. These superior tribological properties are attributable to the remarkable mechanical properties of CNTs and strong bond properties with the APTES film. CNTs film is thus expected to find wider application as high-performance lubricating film in micro/nanoelectromechanical systems (M/NEMS) in future. Carbon nanotubes (CNTs) were successfully assembled on Si substrates via self-assembly technique. Carbon nanotubes film exhibited excellent friction reduction and wear resistance abilities under certain applied load and sliding speed. The relatively long antiwear life of CNTs film may be attributed to the covalent bonding of CNTs to APTES film and the "rolling log" effect of the desorbed CNTs. Compared to SAM developed in M/NEMS, CNTs film are overall more favorable candidate for tribological applications in M/NEMS. [ABSTRACT FROM AUTHOR]

Abstract: A hierarchical Mg/Ni/Al layered double hydroxide (LDH) framework has been fabricated via the in situ crystallization process on aluminum foam (denoted as Mg/Ni/Al LDH/Al-foam). XRD and SEM confirm that the as-prepared Mg/Ni/Al LDH displays flowerlike microspheres (2–5μm) composed of numerous LDH nanoplatelets (1–2μm in width and ~50nm in thickness). The BET analysis shows that the specific surface area of the Mg/Ni/Al LDH is 96.8m²/g owing to its hierarchical structure, which is much higher than that of the traditional bi-metal Mg/Al LDH. Two steps of the synthesis strategy were carried out in order to eliminate the competitive difference between cations composed of LDH. The present work provided a new strategy for a scale-up synthesis of well-crystallized tri-metal LDH materials on metal substrate by the in situ crystallization technique. [Copyright &y& Elsevier]

A structured catalyst has been fabricated by immobilizing cobalt phthalocyanine tetrasulfonate (CoPcS) on a mixed metal oxide (denoted as MMO) film, which exhibits excellent activity, stability and recyclability for mercaptan sweetening. Scanning electron microscopy (SEM) images show that the structured catalyst is composed of MMO nanoflakes whose ab-plane is perpendicular to the Al substrate, with desired mechanical strength and high adhesion to the substrate. In addition, in situ IR spectra and carbon dioxide temperature programmed desorption (CO2-TPD) reveal that the moderate basic site is overwhelming in the CoPcS/MMO structured catalyst, while the strong basic site predominates in the corresponding CoPcS/MMO powder catalyst. It was found that the structured catalyst exhibits high conversion (85.7%) for the oxidation of mercaptan to disulphide, markedly higher than that of the corresponding powder catalyst (38.7%), as a result of the high exposure of active species as well as the synergistic effect between the oxidation center (CoPcS) and the moderate basic site. In addition, the structured catalyst shows superior catalysis-regeneration performance, which facilitates its repeatable and cyclic usage over a long period. Therefore, this work provides a facile and effective method for the fabrication of structured catalyst with high catalytic activity and stability, as well as recyclability, which can be used as an eco-friendly catalyst for the sweetening process in the petroleum refining industry. [ABSTRACT FROM AUTHOR]

Abstract: A novel optical chemosensor was fabricated based on 1-amino-8-naphthol-3,6-disulfonic acid sodium (H-acid) intercalated layered double hydroxide (LDH) film via the electrophoretic deposition (EPD) method. The film of H-acid/LDH with the thickness of 1μm possesses a well c-orientation of the LDH microcrystals confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The fluorescence detection for Hg(II) in aqueous solution was performed by using the H-acid/LDH film sensor at pH 7.0, with a linear response range in 1.0×10−7 to 1.0×10−5 molL−1 and a detection limit of 6.3×10−8 molL−1. Furthermore, it exhibits excellent selectivity for Hg(II) over a large number of competitive cations including alkali, alkaline earth, heavy metal and transitional metals. The specific fluorescence response of the optical sensor is attributed to the coordination between Hg(II) and sulfonic group in the H-acid immobilized in the LDH matrix, which was verified by NMR spectroscopy and UV–vis spectra. In addition, density functional theory (DFT) calculation further confirms that the coordination occurs between one Hg2+ and two O atoms in the sulfonic group, which is responsible for the significant fluorescence quenching of the H-acid/LDH film. The results indicate that the H-acid/LDH composite film can be potentially used as a chemosensor for the detection of Hg2+ in the environmental and biomedical field. [Copyright &y& Elsevier]