Nanobalance Technique Research Articles

Adsorption of Organosilanes and Formation of Organo silicon Self-Assembled Nanolayerson the Aluminum Surface.Influence of Surface Nanolayerson Corrosion and Electrochemical Behavior of the Metal

Adsorption of vinyl triethoxysilane and γ-aminopropyltriethoxysilane on the surface of aluminiumfrom aqueous solutions was studied by quartz nanobalance technique. Adsorption isotherms were obtained. It was shown that during adsorption silanes displace adsorbed water from the surface. To interpret the adsorption data, we used the well-known approaches of adsorption data: Langmuir, BET, Flory-Higgins, Langmuir multicenter,Temkin,Frumkinand Freundlichadsorption isotherms. The surface orientation of adsorbed molecules was determined. The silanes adsorption heats were calculated by different ways. It was shown that silanes are chemisorbed on the aluminium surface. By means of quartz nanobalance, atomic force microscopy, scanning electron microscope, Fourier transform IR spectroscopy it has been shown that an uniform, selfassembled, anti-corrosionvinylsiloxanenanolayer is formed on the aluminium surface during adsorption of vinyl silane from aqueous solution. This layer covalently bonded to the hydroxylsurface groups of the metal. The thickness of the surface nanolayer can be controlled by changing the deposition conditions. The effect of the vinylsiloxanenanolayer on the dissolution of aluminium in chloride-containing solutions has been studied. It was established that an ordered vinylsiloxanenanolayer, up to five molecular layers thickness, effectively inhibits the uniform and localized aluminium corrosion. It was shown that after 10 days of corrosion tests vinylsiloxanenanolayer is preserved on the aluminium surface, indicating its resistance to water and corrosive components.vinylsiloxane Keywords: Aluminium; Adsorption; Alkoxysilane;Organosilicon Self-Assembled Nanolayers; Heterogeneous Processes; Corrosion; Electrode Reactions; Corrosion Test

Application of polydimethylsiloxane/ acrylic resins coated quartz crystal nano balance sensor for detection of glyphosate pesticide

ABSTRACTIn this study, a mixture of polydimethylsiloxane and polyacrylic resins was used as adsorbent for the detection of Glyphosate (GLY) pesticide. A simple and cost-effective analysis method based on Quartz Crystal Nano Balance technique (QCN) was developed to detect GLY. A thin layer of (Polydimethylsiloxane/acrylic resins) mixture was coated on the surface of gold-coated quartz crystal electrodes. The frequency shifts were found to be linear against the concentration of Analytes tested (0.2–8.6 mg/L), with correlation coefficient above 0.98 and sensitivity factor of 70.73 Hz/mg L−1. Among some possible interferences tested (NaCl, CaSO4, MgSO4 and NaHCO3), no major interference was observed in the performance of the sensor.

Application of Molecularly Imprinted Polymer for Determination of Glucose by Quartz Crystal Nanobalance Technique

Accurate determination of glucose is of great importance in various biotechnological processes, food industries, and diagnosing several metabolic disorders. To this point, many methods have been developed to meet this goal. Most of these methods are based on the enzymatic oxidation of glucose. However, the enzymes may be deactivated in different possible condition during storage and use. In this paper, a quartz crystal nanobalance (QCN) modified with a molecularly imprinted polymer (MIP) was developed for online monitoring of glucose in aqueous media without the use of enzymes. The MIP was synthesized by free radical polymerization using different functional monomers, including acrylamide, acrylic acid, allyl alcohol, and acrylonitrile. The findings indicate that acrylic acid has significantly better performance in terms of sensitivity and response time as compared with the other functional monomers. All measurements were performed in a flow cell. The frequency shifts due to the adsorption of glucose were found to be linear versus the concentration of glucose within the concentration range of 10-200 mg L -1 with a correlation coefficient of R 2 = 0.9996. The sensitivity and lower limit of detection of the sensor were found to be 1.20 Hz/mg L -1 and 4.4 mg L -1 , respectively. The results also indicate that organic compounds do not cause any significant interference with glucose determination by the MIPmodified QCN sensor, and using ion exchange resins can eliminate interference of ionic compounds.

Application of nanobalance technique and principal component analysis for detection of the soil fumigant Telone residues in the air

Quartz crystal nanobalance (QCN) technique is considered as a powerful mass sensitive sensor for monitoring of materials in the sub-nanogram level. In the current study, a method based on QCN technique developed to determine Telone in air. Various coating materials including methyl phenyl silicon, 75% phenyl (OV25) and molecularly imprinted polymer (MIP) were employed. The frequency shift of OV25-modified quartz crystal was found to be linear against organohalogen compounds [Telone (soil fumigant), Koril (Herbicide), Endosulfan (organochlorine insecticide) and Chloroform (solvent)] concentrations in the range of 2.4 to 48 mg L−1 for Telone vapor and 4.8–24 mg L−1 for three other vapors. The correlation coefficients for Telone, Koril, Endosulfan and Chloroform were 0.992, 0.996, 0.989 and 0.991, respectively. The principal component analysis was also utilized to process the frequency response data of the organic vapors. Using principal component analysis, it was found that more than 93.85% of the data variance could still be explained by use of two principal components (PC1 and PC2). Subsequently, the successful discrimination of Telone and other compounds was quite possible through the principal component analysis of the transient responses of the OV25-modified electrode. In the second method, a molecularly imprinted polymer-coated sensor for Telone was developed. Molecularly imprinted polymer coated quartz crystal (MIP-QCN) showed a selective response to Telone and gave a linear relationship between frequency shift and amount of Telone from 1 to 48 mg L−1. In this investigation, the proficiency of MIP-QCN and OV25-modified QCN sensors were compared.

A nanogravimmetric investigation of the charging processes on ruthenium oxide thin films and their effect on methanol oxidation

The charging processes and methanol oxidation that occur during the oxidation–reduction cycles in a ruthenium oxide thin film electrode (deposited by the sol–gel method on Pt covered quartz crystals) were investigated by using cyclic voltammetry, chronoamperometry and electrochemical quartz crystal nanobalance techniques. The ruthenium oxide rutile phase structure was determined by X-ray diffraction analysis. The results obtained during the charging of rutile ruthenium oxide films indicate that in the anodic sweep the transition from Ru(II) to Ru(VI) occurs followed by proton de-intercalation. In the cathodic sweep, electron injection occurs followed by proton intercalation, leading to Ru(II). The proton intercalation/de-intercalation processes can be inferred from the mass/charge relationship which gives a slope close to 1gmol−1 (multiplied by the Faraday constant) corresponding to the molar mass of hydrogen. From the chronoamperometric measurements, charge and mass saturation of the RuO2 thin films was observed (440ngcm−2) during the charging processes, which is related to the total number of active sites in these films. Using the electrochemical quartz crystal nanobalance technique to study the methanol oxidation reaction at these films was possible to demonstrate that bulk oxidation occurs without the formation of strongly adsorbed intermediates such as COads, demonstrating that Pt electrodes modified by ruthenium oxide particles can be promising catalysts for the methanol oxidation as already shown in the literature.

Nanomeasurements in Transmission Electron Microscopy

Nanomaterials have attracted a great deal of research interest recently. The small size of nanostructures constrains the applications of well-established testing and measurement techniques, thus new methods and approaches must be developed for quantitative measurement of the properties of individual nanostructures. This article reports our progress in using in situ transmission electron microscopy to measure the electrical, mechanical, and field-emission properties of individual carbon nanotubes whose microstructure is well-characterized. The bending modulus of a single carbon nanotube has been measured by an electric field-induced resonance effect. A nanobalance technique is demonstrated that can be applied to measure the mass of a tiny particle as light as 22 fg (1 fg = 10(-15) g), the smallest balance in the world. Quantum conductance was observed in defect-free nanotubes, which led to the transport of a superhigh current density at room temperature without heat dissipation. Finally, the field-emission properties of a single carbon nanotube are observed, and the field-induced structural damage is reported.

Measuring physical and mechanical properties of individual carbon nanotubes by in situ TEM

Nanomaterials are a fundamental component of nanoscience and nanotechnology. The small size of nanostructures constrains the applications of well-established testing and measurement techniques, thus new methods and approaches must be developed for synthesis, property characterization and device fabrication. This has been the focus of our research, aiming at exploring state-of-the-art techniques for materials processing and characterization. This paper reviews our progress in using in situ transmission electron microscopy to measure the electric, mechanical and field emission properties of individual carbon nanotubes with well-defined structures. Quantum conductance was observed in defect-free nanotubes, which led to the transport of a superhigh current density at room temperature without heat dissipation. A nanobalance technique is demonstrated that can be applied to measure the mass of a tiny particle as light as 22fg (1f=10−15).

Nanomeasurements of individual carbon nanotubes by in situ TEM

Abstract Property characterization of nanomaterials is challenged by the small size of the structure because of the difficulties in manipulation. Here we demonstrate a novel approach that allows a direct measurement of the mechanical and electrical properties of individual nanotube-like structures by in situ transmission electron microscopy (TEM). The technique is powerful in a way that it can be directly correlated to the atomic-scale microstructure of the carbon nanotube with its physical properties, thus providing a complete characterization of the nanotube. Applications of the technique will be demonstrated in measurements of the mechanical properties, the electron field emission, and the ballistic quantum conductance of individual carbon nanotubes. A nanobalance technique is demonstrated that can be applied to measure the mass of a single tiny particle as light as 22 fg (1 f = 10-15 ).

A New Approach Towards Property Nanomeasurements Using In Situ TEM

AbstractProperty characterization of nanomaterials is challenged by the small size of the structure because of the difficulties in manipulation. Here we demonstrate a novel approach that allows a direct measurement of the mechancial and electrical properties of individual nanotube-like structures by in-situ transmission electron microscopy (TEM). The technique is powerful in a way that it can directly correlate the atomic-scale microstructure of the carbon nanotube with its physical properties, providing an one-to-one correspondence in structure-property characterization. Applications of the technique will be demonstrated on mechanical properties, the electron field emission and the ballistic quantum conductance in individual nanotubes. A nanobalance technique is demonstrated that can be applied to measure the mass of a single tiny particle as light as 22 fg (1 f= 10−15).