Iranian Journal of Materials Science and Engineering

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Graphene oxide thin layers, graphene oxide:silver nano-composite, graphene oxide:zinc oxide nano-composite and graphene oxide:zinc oxide/graphene oxide:silver bilayer were deposited by spray pyrolysis method. The synthesized thin layers were characterized using X-ray diffraction spectroscopy, field emission scanning electron microscope, energy dispersive x-ray spectroscopy and Raman spectroscopy. The optical properties and the band gap of the thin layers were also studied and calculated using the Tauc equation. Gram-negative bacterium of Escherichia coli was used to study the antibacterial properties of thin layers. The results showed that among the thin layers investigated, GO:ZnO/GO:Ag bilayer had the greatest effect on the inhibition of E. coli growth and was able to control the growth of bacterium after 2 hours.

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Background: Superhydrophobic materials which have contact angle higher than 150°, considering their widespread applications, are very important for researchers.
Method: In this research, silica nanopowder was synthesized successfully using inexpensive sodium silicate source and very simple and facile method. Synthesis of hydrophobic solution was carried out by sol-gel method. The surface modification of silica nanopowder was performed using different silane/siloxane polymers and was deposited on glass slides. For characterization of the samples XRD, FESEM, EDX, TEM, FTIR, and Raman analysis were used.
Results: The XRD result shows a very wide peak at 2q = 24.7° which indicates the amorphous nature of the silica particles. The results of the performed characteristics confirm the synthesis of silica nanopowder with the size of less than 25 nm. The EDX spectrum shows that only Si and O elements are present in the structure and no impurities are visible. The contact angle between water droplet and thin films was measured and the effect of different synthesis parameters on the contact angle was studied. Among the studied polymers and solvents, the most hydrophobicity was obtained using TMCS polymer and xylene solvent. The optimized sample has a maximum contact angle of 150.8°.
Conclusion: The synthesized thin films have superhydrophobic properties and the method used in this research can be developed for use in industrial applications.

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This research is focused on the synthesis of zinc oxide nanoparticles by means of the sol-gel conventional method, followed by the formulation of a zinc oxide-polypropylene (ZnO: PP) masterbatch using a twin-screw extruder. The next step involved the fabrication of antibacterial fibers through electrospinning. The resulting Nano powders, masterbatch, and fibers were subjected to a series of characterization techniques. X-ray diffraction (XRD) was used to examine the crystalline structure, field emission scanning electron microscopy (FESEM) was employed to scrutinize the morphology of the samples, energy-dispersive X-ray spectroscopy (EDX) was adopted for elemental analysis, and Fourier-transform infrared spectroscopy (FTIR) was hired to identify the chemical bonds.
Thermogravimetric analysis (TGA) indicated a three-stage weight loss process, and differential scanning calorimetry (DSC) showed a primary endothermic peak centered at about 317 °C and a pronounced exothermic peak at approximately 455 °C. XRD confirmed the hexagonal wurtzite structure of the zinc oxide nanoparticles and the presence of the alpha (α) crystal form in polypropylene. FESEM imaging revealed that the zinc oxide and masterbatch samples had a uniform size and shape, predominantly in the nanometer range with an elongated spherical morphology. The antibacterial properties of polypropylene fibers containing varying concentrations of zinc oxide, including 1.2, 2.4, and 5 wt.%, were tested against Escherichia coli and Staphylococcus aureus.