Safer Production of Water Dispersible Carbon Nanotubes and Nanotube/Cotton Composite Materials

Water-dispersible carbon nanotubes (WD-CNTs) have great importance in the fields of biotechnology, microelectronics, and composite materials. Sidewall functionalization is a popular method of enhancing their dispersibility in a solvent, which is usually achieved by strong acidic treatment. But, treatment under such harsh conditions deviates from green chemistry and degrades the structure and valuable properties of CNTs. Alternative safer and easier plasma method is discussed to produce functionalized CNTs (f-CNTs). The f-CNTs remain dispersed in water for more than 1 month owing to the attachment of a large number of carboxyl groups onto their surfaces. The WD-CNTs are applied to produce conductive cotton textile for the next generation textile technologies. Nonconducting cotton textile becomes electroconductive by repeatedly dipping into the f-CNT-ink and drying in air. The f-CNTs uniformly and strongly cover the individual cotton fibers. After several cycle of dipping into the f-CNT-ink, the textile becomes conductive enough to be used as wire in lighting up an LED. As a demonstration of practical use, the textile is shown as a conductive textile heater, where the textile can produce uniformly up to ca. 80°C within ca. 5 min by applying an electric power of ca. 0.1 W/cm2

Water-Dispersible Multiwalled Carbon Nanotubes Obtained from Citric-Acid-Assisted Oxygen Plasma Functionalization

A new and safe method has been developed to functionalize multiwalled carbon nanotubes (MWCNTs) with fewer surface defects, which significantly increases their dispersibility in water. MWCNTs are pretreated in pure ethanol by a supersonic homogenizer. Then, the mixture is dried and soaked in weak citric acid solution. Finally, the MWCNTs in the citric acid solution are treated with radio frequency (13.56 MHz) oxygen plasma. As a result, many carboxyl functional groups are attached onto the MWCNT surfaces and stable dispersion of the MWCNTs in water is obtained. The treatment conditions are optimized in this study

DFT Based LDA Study on Tailoring the Optical and Electrical Properties of SnO and In-Doped SnO

In this paper, the structural, electronic and optical properties of tin-monoxide and the impact of Indium (In) doping into tin-monoxide are computed by Local Density Approximation (LDA) under density function theory (DFT) framework. The calculated bond length of Sn-O in tin-monoxide is 2.285 angstrom and that deviates greater than 3 percent from the experimental value. The Sn-O and In-O bond lengths in In-doped tin-monoxide are calculated to be 2.3094 and 2.266 angstrom, respectively. Interestingly, the band gap of pure tin-monoxide is calculated to be 2.61 eV whereas it is significantly dropped down to 2.00 eV in the case of In doped tin-monoxide. The Total Density of State (DOS), Partial DOS and electron density are depicted for tin-monoxide and In-doped tin-monoxide films. As a consequence of In-doping static value of the refractive index and real part of the dielectric function for tin-monoxide decrease from 1.9 to 1.4 and 3.6 to 1.97, respectively. Therefore, In-doping enhances the properties of the tin-monoxide film, which may lead the material to be applied in future to develop electronic and opto-electronic devices

炭素ナノチューブの合成、機能化および応用に関する研究

博士(学術)doctoral創造科学技術大学院静岡大学甲第820号ET

Conductive Cotton Textile from Safely Functionalized Carbon Nanotubes

publishe

Development of Compact Load Cell Using Multiwall Carbon Nanotube/Cotton Composites and Its Application to Human Health and Activity Monitoring

publishe

Structural and optical behaviours of methyl acrylate-vinyl acetate composite thin films synthesized under dynamic low-pressure plasma

Low-pressure (33.33 Pa) plasma polymerized methyl acrylate and vinyl acetate composite thin films with various monomer compositions were deposited onto glass substrates. Under the same plasma conditions, the homopolymer thin films were also prepared. The thickness of the composite films was observed to vary between 117 and 213 nm depending on the monomer ratio. The composite films exhibit a smooth, pinhole-free, and immaculate surface morphology, surpassing that of the homopolymers. The energy dispersive x-ray study shows that the films contain mainly carbon and oxygen with 26.09–37.20 at% and 35.03 − 40.10 at%, respectively. The composite films contain more carbon contents which enhance the film stability. The appearance of some broad absorption bands in the Fourier transform infrared spectroscopy indicates structural changes in the PP films caused by the restructuring or dilapidation of monomer molecules while forming the polymer. The UV–visible spectra analysis reveal that the composite films exhibited a tunable optical band gap by adjusting the monomer ratio. The decrease of methyl acrylate monomer reduces the direct and indirect optical band-gap values of composite films from 3.15 to 3.00 eV and 2.35 to 1.74 eV, respectively. While Urbach energy values increases from 0.33 eV to 0.90 eV. All the films showed good transmittance properties (86 − 96%) in the visible range wavelength (550 − 800 nm). Other optical parameters are also found better in composite films which indicates the aptness of the composite films in various optoelectronic or electronic applications