Nano

Nanotechnology offers fundamentally new capabilities to architect a broad array of novel materials, composites and structures on a molecular scale. It is potentially capable of redefining the methods used for developing lighter, stronger, high-performance structures and processes with unique and nontraditional properties. This review summarizes different classes of nanocarbon-based polymer composites and their applications. Also, it highlights different ways to create smaller, cheaper, lighter and faster devices using nanocarbon-based polymer composites. The potential applications of such materials are in the fields of membrane, aviation, electronics, polymer composites, as well as the marine and transport industries. A detailed description of nanocarbon-based composite materials manufactured from PE, PP, PS, PS, PVC, PPS, ABS, PMMA, nitrile rubber, etc. is also reviewed. Some of the major applications of carbon-based polymer nanocomposites are in the tyre industry, semiconductors, and many more, which has brought about the new, developing and exciting research field called nanoscience.

The precursory carbon source is one of the key parameters which govern the formation of carbon nanotubes (CNTs). In this work, by selecting four homologous series, namely n-pentane, n-hexane, n-heptane and n-octane, as investigated targets, we comparatively study the relationship between thermodynamic properties of the precursory carbon source and formation of aligned CNTs. We find that all of these alkanes are favored for the growth of aligned CNTs in a suitable growth environment. But only n-heptane can yield the aligned CNTs with relatively high quality, high yield and narrow diameter distribution. Furthermore, after considering the link between thermodynamic properties of the precursory carbon source and the morphology characteristic of the nanotube samples, we find that the Gibbs free energy and formation enthalpy of precursory carbon sources play critical roles in the nanotube formation. In additions some possible explanations are proposed to better understand these phenomena. These rules will be very helpful in making clearer the formation mechanism from the precursory carbon sources to the CNTs, and preparing large-scale aligned CNTs with diameter control at low cost.

Castor oil (combination of fatty acids) precursor containing hydrocarbon with less amount of oxygen is used first time for synthesis of different carbon nanostructures (i.e., agglomerated carbon nanoparticles, carbon nanobeads and carbon tubular structure). The agglomerated carbon nanoparticles, carbon nanobeads and carbon tubular structure were synthesized by applying CVD method at different temperature using castor oil as new carbon precursor without any catalyst. The synthesis of carbon nanostructure is free from additional catalyst as this hydrocarbon (castor oil) is cheap with abundant sources of carbon. The effect of pyrolysis temperatures on the size, quality and quantity of the synthesized carbon shape were investigated. Interestingly, the morphology of the carbon nanostructures can be controlled in shape from agglomerated carbon nanoparticle to nanobeads to carbon tubular structure just by increasing the temperature from 750°C to 800°C to 850°C, respectively. These nanobeads are chains of uniform size of graphitized carbon spheres. These chains comprised individual carbon particles size of ~ 450 nm. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR).

We present a theoretical model capable of identifying multiple adsorption sites in a gas storage material with different binding energies and different amounts of adsorbed molecules. By applying this model to experimental data on the hydrogen storage in MOFs, we extract hydrogen adsorption properties of MOFs with coexisting strong and weak adsorption sites.

Molecular dynamics simulation is used to observe the traveling behavior of a water cluster released from the interior of single-walled carbon nanotube (SWCNT) to a graphite sheet. The simulation results reveal that there is a need for the water cluster overcoming the energy barrier of the binding energy between the water cluster and the SWCNT to escape from the tube. The water cluster undergoes a three-dimensional motion when released from the SWCNT, due to the effect of the thermal velocity. When encountering the graphite sheet in the forward direction, the x axis impact velocity has much effect on the delivery of the water cluster. The fact that the water cluster is bounced back reduces the possibility of being captured by the graphite sheet, resulting in a decrease in the delivery efficiency of the water cluster. The presence of the electric charges can help the graphite sheet to effectively trap the water cluster. These results have implications for the design and fabrication of novel drug delivery devices.

Pseudopolyrotaxanes, Ps-PR, consisting of α-cyclodextrin rings, polyethylene glycol axes and end triazine groups were prepared and then were capped by amino-functionalized quantum dots, NH₂-QDs, to achieve polyrotaxanes. The amino-functionalized QDs stoppers of polyrotaxanes were used as core to synthesize polyamidoamine, PAMAM, dendrons divergently and hybrid nanomaterials were obtained. Synthesized hybrid nanomaterials were characterized by different spectroscopy, microscopy and thermal analysis methods. They were freely soluble in water and their aqueous solutions were stable at room temperature over several months. Due to their biocompatible backbone, high functionality and water solubility synthesized hybrid nanomaterials are promising carriers and probes in cancer diagnosis and therapy.

Optical constants of cadmium sulfide (CdS) thin films were determined in the spectral range of 400–1200 nm from optical absorption and transmittance measurements for different bath temperatures. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) were the techniques used to determine the crystallite structure and morphology of the films. EDX images showed that a sample had a stoichiometric composition. The crystallite size and microstrain were calculated using the Williamson–Hall method. The optical band gap values of the films varied from 2.35 eV to 2.5 eV, depending on the bath temperature. Optical study was performed to calculate the refractive index (n), extinction coefficient (k), optical conductivity (σ), dielectric constant (real and imaginary), and optical band gap using transmission spectra. It has been observed that the conductivity of the synthesized films has a close relationship with the size of the crystallites. The optical conductivity and the crystallite size increase at a temperature of up to 70°C and then start decreasing when the temperature is still increased due to the change in phase from hexagonal to cubic in nature. Moreover, we observed that beyond this temperature the XRD peak shifts toward the nanoregion. The values of microstructure parameters change drastically, whereas the trend of optical constants remains the same.

We report the effects of 70 keV proton (H⁺) irradiation on the structure of zinc oxide nanowires (ZnO NWs) for a wide range of irradiation doses at room temperature. It was found that at low dose 5 × 10¹⁵ ions/cm² of protons, few defects were created in ZnO NWs and the defects' density was increased with an increasing proton irradiation dose. After the irradiation dose was increased to 2 × 10¹⁷ ions/cm², the crystal structure of the ZnO NWs was almost completely damaged and the crystalline wurtzite structure of the ZnO NWs could be transformed into a disordered amorphous structure. Structural changes in the ZnO NWs upon bombardment with 70 keV protons were characterized by high resolution transmission electron microscopy (HRTEM).

ZnO films with well-aligned hierarchical structures have been successfully synthesized at moderate temperatures using a simple catalyst-free hydrothermal process. The synthesized ZnO films are found to be single-phase, with a hexagonal wurtzite-type structure. Scanning electron microscopy images show that the well-aligned hierarchical structures are assembled with interlaced parallel sheets grown on the (400) silica surface. The water contact angle measurement indicates that the water on the films has a contact angle of about 156.3°. This clearly demonstrates that the ZnO films synthesized by this simple method have superhydrophobic properties and may be important for applications in self-cleaning surfaces, biology, and so on.

PET/SiO₂ layers were chemically modified to maintain immobilization of functional single molecules. GFP molecules provide an ideal system due to their stability and intrinsic fluorescence. GFP in vivo biotinylated within its NH₂-terminal region and attached on the substrate via the biotin–streptavidin bond was further investigated with confocal microscopy, atomic force microscopy (AFM) and spectroscopic ellipsometry (SE). AFM revealed monolayered donut-like structures representing assemblies of biotin–streptavidin–biotin–GFP immobilized onto PET/SiO₂ surfaces via mPEG. In particular, regions with an approximate height of 12 nm, which approaches the molecular dimensions of the above complex given by molecular modeling, could be detected. The dimensions of the donut-like structures suggest a close-to-each-other positioning of the GFP molecules — which, however, retain their functionality, as evidenced by confocal microscopy.

The complex perovskite Ba₂YbZrO_5.5 has been successfully synthesized as nanoparticles through a single step combustion process for the first time. The X-ray diffraction analysis revealed that the combustion product is phase-pure and has an ordered cubic perovskite structure. Transmission electron microscopy results indicated that the particle sizes are 10–20 nm. The selected area electron diffraction pattern has shown that as-prepared powder is polycrystalline in nature. The UV–visible spectrum analysis confirmed that the optical absorption edge of Ba₂YbZrO_5.5 is around 340 nm, corresponding to a band gap of ~ 3.65 eV. Photocatalytic activity of Ba₂YbZrO_5.5 nanoparticles is investigated for the degradation of methyl orange under solar irradiation.

A new nanocomposite based on SBA-15 mesoporous materials combined with Fe₂O₃ and CoFe₂O₄ nanoparticles was prepared via sol–gel growth. The nanostructures and magnetic properties of the SBA-15 nanocomposite were investigated by X-ray diffraction topography, high resolution transmission electron microscopy, and vibrating sample magnetometer. Results indicate that α-Fe₂O₃ nanoparticles are present in the frame or micropores of SBA-15 (denoted as Fe–SBA-15 below) and that CoFe₂O₄ nanoparticles are confined in the mesoporous channels of Fe–SBA-15. Our results also reveal that the addition of CoFe₂O₄ and α-Fe₂O₃ magnetic nanoparticles critically affects their magnetic properties. The saturation magnetization of the SBA-15 nanocomposite is attributed to ferrimagnetic CoFe₂O₄ nanoparticles and antiferromagnetic α-Fe₂O₃ nanoparticles, whereas the coercivity increases with the content of CoFe₂O₄. Moreover, the presence of the couple exchange interaction between the magnetic nanoparticles is confirmed, which can enhance the magnetic properties of the SBA-15 nanocomposite.