The hydrothermal and the co-precipitation methods were used for the formation of new multifunctional MWCNTs/NiFe
2
O
4
/ZnO (MNFZ) hybrid nanostructures. The MNFZ hybrid nanostructure formation was ...asserted by characterizing it via the X-ray diffraction (XRD) analysis and TEM. Then, the casting technique was used for preparing the MNFZ nanoparticle-doped Poly (vinyl alcohol) (PVA) and poly (ethylene oxide) (PEO) by various concentrations of MNFZ NPs as nanofiller. All polymer blend and nanocomposite films are shown by XRD studies to have a semicrystalline nature with a reduced degree of semi-crystallinity with the dopant. The infrared absorption band shift and the intensity change indicate the interaction or complexation between the blend and nanofiller is confirmed by FTIR studies. The volume percentage variation of the nanoparticles and the ferromagnetic response variation of the nanocomposite were in consistency. The dielectric characteristics and ac conductivity of the film polymer blend were higher upon adding the nanofiller because the charge carrier number was higher. Such features of MNFZ-doped PVA/PEO films prove their appropriateness as materials for electromagnetic applications.
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•The SWCNTs/TiO2 nanostructure fabricated by a simple mixing technique.•Nanocomposites samples of CMC/PEO-SWCNTs/TiO2 were successfully prepared by casting method.•How can these ...nanocomposites (CMC/PEO-SWCNTs/TiO2) be fine-tuned to have diverse thermal, optical and electrical properties?•The optical properties of the prepared films were determined.•The nanocomposite film of CMC/PEO containing 3.2 wt.% of SWCNTs/TiO2 has the maximum ionic conductivity properties.
The TiO2 NPs have been successfully synthesized by sol-gel method and the SWCNTs/TiO2 nanostructures have been fabricated by a simple mixing technique. By a solution casting process, pure CMC/PEO and SWCNTs/TiO2 nanohybrid doped CMC/PEO polymer blend films have been prepared. The influence of SWCNTs/TiO2 nanohybrid loading on the thermal, optical, and conductivity properties of the polymer blend has been discussed. The XRD pattern shows that the average crystallite size of the nanoparticles for TiO2 and SWCNTs/TiO2 is 20 nm and 15 nm, respectively, and a change in crystallinity was observed with an increase in doping. The interaction between CMC/PEO chains and SWCNTs/TiO2 nanohybrid is confirmed by FTIR spectra. The optical absorption spectrum shows that the energy gap reduces with the dopant increase. The miscibility between the CMC and PEO was confirmed by DSC thermograms. With an increase in dopant content, the TGA study demonstrates that the system's thermal stability improves. The maximum value of the blend's AC conductivity is 4.77 10−6 S/m, and by increasing the loading of SWCNTs/TiO2 to 3.2 (wt%) increased to 9.23 10−4 S/m. The conduction mechanism changed with SWCNTs/TiO2 loading from the correlated barrier hopping, in the prepared samples. Usage of these nanocomposite films in the semiconductor industry is encouraged by the observed improvements in optical, thermal, and AC conductivity.
Due to their unique structural, physical and chemical properties, cyclodextrins and their derivatives have been of great interest to scientists and researchers in both academia and industry for over ...a century. Many of the industrial applications of cyclodextrins have arisen from their ability to encapsulate, either partially or fully, other molecules, especially organic compounds. Cyclodextrins are non-toxic oligopolymers of glucose that help to increase the solubility of organic compounds with poor aqueous solubility, can mask odors from foul-smelling compounds, and have been widely studied in the area of drug delivery. In this review, we explore the structural and chemical properties of cyclodextrins that give rise to this encapsulation (i.e., the formation of inclusion complexes) ability. This review is unique from others written on this subject because it provides powerful insights into factors that affect cyclodextrin encapsulation. It also examines these insights in great detail. Later, we provide an overview of some industrial applications of cyclodextrins, while emphasizing the role of encapsulation in these applications. We strongly believe that cyclodextrins will continue to garner interest from scientists for many years to come, and that novel applications of cyclodextrins have yet to be discovered.
Stevia rebaudiana
plant leaves were used for biosynthesis of gold nanoparticles (AuNPs). Transmission electron microscope images showed various shapes and sizes of AuNPs. Various amounts of AuNPs ...were added to polyvinyl alcohol/carboxymethylcellulose (PVA/CMC, 40/60) via the casting method. The X-ray diffraction (XRD) spectrum of pure blend shows the amorphous nature of the blend. FTIR spectra showed the interaction between PVA/CMC and AuNPs. The ultra-violet and visible spectra showed emerging new peak of surface plasmon resonance of AuNPs for the filled samples. The scanning electron microscope images showed bright spots on the sample’s surface, which was attributed to AuNPs. AC conductivity exhibited enhancement after the addition of gold nanoparticles. The
ε
′ and
ε
″ were reduced with increasing the frequency due to direction dipoles of applied electric field. Because of the mobile charges inside the polymeric backbone, higher values of
ε
′ and
ε
″ were observed at low frequencies. The tan
δ
showed increased with an increase in AuNPs concentration and decrease at high frequency, as expected.
Advanced wireless communication technology claims miniaturized, reconfigurable, highly efficient, and flexible meta-devices for various applications, including conformal implementation, flexible ...antennas, wearable sensors, etc. Therefore, bearing these challenges in mind, a dual-band flexible metamaterial absorber (MMA) with frequency-reconfigurable characteristics is developed in this research. The geometry of the proposed MMA comprises a square patch surrounded by a square ring, which is mounted over a copper-backed flexible dielectric substrate. The top surface of the MMA is made of silver nanoparticle ink and a middle polyethylene terephthalate (PET) substrate backed by a copper groundsheet. The proposed MMA shows an absorption rate of above 99% at 24 and 35 GHz. In addition, the absorption features are also studied for different oblique incident angles, and it is found that the proposed MMA remains stable for θ = 10–50°. The frequency tunability characteristics are achieved by stimulating the capacitance of the varactor diode, which connects the inner patch with the outer ring. To justify the robustness and conformability of the presented MMA, the absorption features are also studied by bending the MMA over different radii of an arbitrary cylinder. Moreover, a multiple-reflection interference model is developed to justify the simulated and calculated absorption of the proposed MMA. It is found that the simulated and calculated results are in close agreement with each other. This kind of MMA could be useful for dual-band sensing and filtering operations.
Summary
Solution casting and ultrasonic‐assisted solution‐cast methods were used to create polymer nanocomposites films based on polyvinyl alcohol (PVA)/polyvinyl pyrrolidone (PVP) filled with ...varying concentrations of BaTiO3 nanoparticles. The X‐ray diffraction (XRD), Fourier‐transform infrared (FT‐IR), transmission electron microscope, and differential scanning calorimetry (DSC) were used to study the properties of the produced polymer nanocomposite samples. The properties of PVA/PVP‐BaTiO3 nanocomposites, such as ac conductivity, dielectric constant, and dielectric loss, were investigated as a function of BaTiO3 concentration. XRD measurements demonstrate that the pure polymer blend is semi‐crystalline and that the crystallinity degree (Xc) of the doped PVA/PVP mix films is lower than that of the pure blend. Significant variations in the FT‐IR spectra demonstrate the interaction between the BaTiO3 ions and the PVA/PVP matrix. The DSC analysis demonstrates that the PVA/PVP has a single glass transition temperature (Tg), showing that the two polymers are miscible. In addition, when the amount of BaTiO3 NP's increased, the Tg of the nanocomposite films decreased. The AC conductivity spectra of all samples obey Jonscher's power law. For a better understanding of charge storage characteristics and conductivity relaxation, dielectric constant and loss investigations have been carried out. The PVA/PVP mixed with 1.5 wt% BaTiO3 nanofiller achieves a maximum ionic conductivity of ~8.57 × 10−5 S/cm. In this investigation, which introduced a novel approach, the complex permittivity revealed that the real part value of the dielectric constant (ε′) for all samples was much bigger than the imaginary part (ε″) value. These results are predicted to have a significant influence on a variety of applications, including polymer organic semiconductors, energy storage, polymer solar cells, and nanoelectronics.
Solution casting and ultrasonic‐assisted solution‐cast methods were used to create polymer nanocomposites films based on polyvinyl alcohol (PVA)/polyvinyl pyrrolidone (PVP) filled with varying concentrations of BaTiO3 nanoparticles. The X‐ray diffraction (XRD), Fourier‐transform infrared (FT‐IR), transmission electron microscope, and differential scanning calorimetry (DSC) were used to study the properties of the produced polymer nanocomposite samples.
We aimed to augment the proton conductivity of poly(vinyl alcohol) (PVA) by crosslinking polyvinyl pyrrolidone (PVP) with PVA without any crosslinkers for the first time to form polyvinyl ketal ...(PVKL). Several characterization techniques were used, including Fourier transform infrared (FT‐IR), proton nuclear magnetic resonance (1H‐NMR), X‐ray diffraction (XRD), and thermogravimetric analysis (TGA). To investigate the wettability and proton conductivity performances of the PVKL film, the contact angle, water uptake, and proton conductivity were also evaluated. The PVKL film exhibited excellent water uptake ability (>400%); its proton conductivity was 100 mS cm−1 at 110°C. The proton conductivity of PVKL film increases because PVKL film has a larger charge carrier concentration owing to ketal ring formation. The results point to the longer lifespan for the PVKL film and reveal that the film exhibits excellent proton conductivity rather than PVA film. Thus, it can be potentially used in various optoelectronic applications.
The evidence of the formation of ketal rings between PVA and PVP via FTIR spectra recorded for PVA and its polyvinyl ketal counterpart.
The recent unusual weather changes occurring in different parts of the world are caused by global warming, a consequence of the release of extreme amounts of greenhouse gases into the atmosphere. ...Carbon dioxide (CO2) is one of these greenhouse gasses, which can be captured and reused to generate fuel through the methanation process. Nickel- and silica-based catalysts have been recognized as promising catalysts due to their efficiency, availability, and low prices. However, these catalysts suffer from metal sintering at high temperatures. Researchers have achieved remarkable improvements through altering conventional synthesis methods, supports, metal loading amounts, and promoters. The modified routes have enhanced stability and activity while the supports offer large surface areas, dispersion, and strong metal–support interactions. Nickel loading affects the formed structure and catalytic activity, whereas doping causes CO2 conversion at low temperatures and forms basic sites. This review aims to discuss the CO2 methanation process over Ni- and SiO2-based catalysts, in particular the silica-supported Ni metal in previously reported research works and point out directions for potential future work.
Abstract
The study used a one-step hydrothermal method to prepare Fe
3
O
4
–FeVO
4
and xRGO/Fe
3
O
4
–FeVO
4
nanocomposites. XRD, TEM, EDS, XPS, DRS, and PL techniques were used to examine the ...structurally and morphologically properties of the prepared samples. The XRD results appeared that the Fe
3
O
4
–FeVO
4
has a triclinic crystal structure. Under hydrothermal treatment, (GO) was effectively reduced to (RGO) as illustrated by XRD and XPS results. UV–Vis analysis revealed that the addition of RGO enhanced the absorption in the visible region and narrowed the band gap energy. The photoactivities of the prepared samples were evaluated by degrading methylene blue (MB), phenol and brilliant green under sunlight illumination. As indicated by all the nanocomposites, photocatalytic activity was higher than the pure Fe
3
O
4
–FeVO
4
photocatalyst, and the highest photodegradation efficiency of MB and phenol was shown by the 10%RGO/Fe
3
O
4
–FeVO
4
. In addition, the study examined the mineralization (TOC), photodegradation process, and photocatalytic reaction kinetics of MB and phenol.
The casting method was employed for the preparation of polymer blend films doped with TiO2 (0.5, 1, 1.5, and 2.3 wt%). The TiO2 phase formation is anatase, with an average crystal size of 20.25 nm, ...according to the XRD results. The samples of PANI/PMMA-TiO2 nanocomposite are amorphous nature. Furthermore, as the concentration of TiO2 NPs increases, the amorphousity degree increases. The FTIR technique is used to reveal the nanocomposites' vibrational bands as well as the intermolecular bonding between the blend and the TiO2 NPs. Absorption spectra, reflectance, transmission spectra, extinction coefficient, refractive index, real and imaginary parts of the dielectric constant, third-order susceptibility (χ3), and optical band gaps are among the optical constants studied. As preselected TiO2 NPs are put into thin films (doping ≤1.5 wt%), the optical band gap values (Eg) of the fabricated nanocomposite films decreased. These results are extremely similar to those obtained using the Tauc method. DSC and TGA techniques show that TiO2 NPs help to improve the thermal stability of the polymer blend. The DSC measurement reveals a single Tg of the polymer blend (PANI/PMMA), indicating that the two polymers are miscible. The optical constants revealed noticeable changes with increasing doping concentrations; according to the experimental data. The doped thin films that were developed have a great promise for manufacturing high-efficiency optoelectronic devices.
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•TiO2 nanoparticles were prepared by a sol-gel method.•PANI was synthesized by chemical oxidative polymerization technique.•FT-IR was used to confirm the presence interaction between PANI/PMMA and TiO2 NPs.•The TGA curves show that the thermal stability of the nanocomposite films.•The optical constants displayed noticeable changes upon raising the doping concentrations.
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