Issue 7


Recent development of the triboelectric properties of the polymer: A review

Hanjun Ryu; Sang-Woo Kim

Advanced Materials Letters, 2018, Volume 9, Issue 7, Pages 462-470
DOI: 10.5185/amlett.2018.1869

Smart sensors and network systems are commonly referred to as Internet of Things (IoT) and are being used to realize a smart society. Although the development of low-power smart systems and large-capacity batteries is increasing the usage time of IoT devices, the time-limited capability of such systems reveals a need for self-powered sensors and systems for sustained IoT use. Mechanical energy is easily accessible from the environment to power sensors and systems. The triboelectric nanogenerator (TENG) converts mechanical energy into electric energy was first introduced in January 2012 by Wang et al., and we describe recent developments in the triboelectric properties of the polymers because the contact electrification between the two different materials is a key factor of TENG. This review article discusses the four operating modes of TENG, the working mechanism, the theoretical modelling of the vertical TENG, and the research aspects of the material.

Sensitivity enhanced photo-thermal borders detection in bio-phantoms enriched with gold nanoparticles

Yossef Danan; Ariel Schwarz; Moshe Sinvani; Zeev Zalevsky

Advanced Materials Letters, 2018, Volume 9, Issue 7, Pages 471-475
DOI: 10.5185/amlett.2018.1860

In the last decade diversity of applications in the fields of diagnostics and treatment for biomedical applications using gold nanoparticles (GNPs) as contrast agent sprang up. The strong optical absorption and scattering properties of the GNPs due to their localized surface plasmon resonance (LSPR) effect enables their use as contrast agents in these applications. The usage of the light-scattering properties of the GNPs in most imaging methods lead to background noise stems from light scattering from the tissue due to the same wavelengths of the illumination source and the GNPs’ scattering. In our previous works we presented a method to improve border detection of bio-phantoms enriched with GNPs leading for real-time complete tumor resection by using a modulated laser illumination, photo thermal imaging camera and the optical absorption of specially targeted GNPs. In this system the thermal camera detects the temperature field of the illuminated bio-phantoms. Although the surrounding area got heated the border location was detected at a precision of at least 0.5 mm through use of a simple post processing technique. In this paper, we present a continuation of our previous research with modified system of time sequence labelling (TSL) processing for improved border detection capable of operating and detecting borders at much lower signal to noise levels.

Percolation-induced low frequency plasmonic state in metal granular composite materials

Takanori Tsutaoka; Herieta Massango; Teruhiro Kasagi

Advanced Materials Letters, 2018, Volume 9, Issue 7, Pages 476-480
DOI: 10.5185/amlett.2018.2053

Low frequency plasmonic (LFP) state induced by the electrical percolation of metallic particles has been investigated for metal granular composite materials containing Cu, Ni47Fe53 and Co50Fe50 microparticles. In these composites, a conductivity jump due to electrical percolation takes place at different particle volume fraction j; a conductive state is established above the percolation threshold jC. The jC is 0.16 for Cu, 0.61 for Ni47Fe53, and 0.76 for Co50Fe50 composites, respectively. In the Cu composite, the LFP state takes place in the conductive state just above jC. However, in the Ni47Fe53 composite, the LFP state is established at j = 0.90; the LFP state couldn’t be observed in the Co50Fe50 one. Hence, a non-plasmonic conductive state can exist in the percolated state; the LFP state can be established in the conductive state with about 1.0 S/cm of the conductivity value. 

Swift heavy ion induced modifications in the structural, optical and methane sensing properties of indium oxide thin films - A comparative study using Ag9+ and O7+ ion irradiation

Riti Sethi; Anver Aziz; G.B.V.S. Lakshmi; D.K. Avasthi; Azher M. Siddiqui

Advanced Materials Letters, 2018, Volume 9, Issue 7, Pages 481-487
DOI: 10.5185/amlett.2018.2033

Thin films of indium oxide grown on quartz substrates were subjected to 100 MeV Ag 9+ and O 7+ ions irradiation. The pristine and swift heavy ions irradiated films were characterized using X-ray Diffraction, Rutherford Backscattering Spectrometry, Scanning Electron Microscopy and UV-Vis Spectroscopy to examine the effect of irradiation with ions having large difference in the values of electronic energy loss (Se) on the structural, microstructural and optical properties of indium oxide thin films. XRD and SEM studies revealed deterioration in crystallinity along with decrease in both crystallite size and grain size upon irradiation with both Ag 9+ and O 7+ ions. However, the decrease in the crystallite size and grain size in comparison to the pristine film was more radical for irradiation with Ag 9+ ions. RBS spectra suggest that the electronic sputtering in the indium oxide films due to SHI irradiation is very less. AFM images illustrate the decrease in surface roughness from 29.8 nm for the pristine film to to 27.4 nm and 26.7 nm on irradiation with 100 MeV O 7+ and Ag 9+ ions at a fluence of 3.3×10 13 ions/cm 2 .  Also, UV-Vis study revealed an increment in the value of optical band gap from 3.41 eV for the pristine film to 3.53 and 3.67 eV for indium oxide films irradiated with of 3.3×10 13 ions/cm 2 fluence of O 7+ and Ag 9+ ions respectively. The irradiation induced structural and optical modifications have been explained using the Thermal spike model. Along with the structural and optical properties, sensing properties of the pristine and irradiated films for 100 ppm methane gas at an operating temperature of 300 o C have also been examined and the results have been correlated with the induced structural modifications.

Effect of the BMIM BF4 immobilization on oxidized activated carbon in fuel desulfurization

Misael D. Cogollo Valdes; Magda A. Salazar Vega; Melissa J. Cely Pinto; Ana M. Pinilla Torres; Jessica V. Ardila Antolínez; Marisol Fernández Rojas; Luz A. Carreño Diaz*

Advanced Materials Letters, 2018, Volume 9, Issue 7, Pages 488-493
DOI: 10.5185/amlett. 2018.2065

Environmental consequences of high consumption of fossil fuels containing sulfur compounds have promoted research in technologies for their removal. Catalytic hydrodesulphurization currently used requires high temperature and pressure. Alternative technologies based on ionic liquids pure and anchored to matrices have shown good desulfurization properties. Composites offer advantages of reuse, less time consuming and costs, using lower IL amount. In this work, we obtained a solid composite containing [BMIM][BF4] supported on oxidized active carbon and characterized by FTIR, BET, TGA-DSC, and SEM. We evaluated the extraction capacity of benzothiophene, thiophene, dibenzothiophene, and diphenyl sulphide from a model fuel with both pure [BMIM][BF4] as well as the same IL on oxidized activated carbon. In the extraction process using pure IL were achieved removal percentages of up to 69.8% whereas with the composite it was possible to reduce 80 % of the sulfur content. 

Synthesis and study of optical properties of microstructure flower-shaped ZnO 

Rajat K. Saha; Eeshankur Saikia;Mrinal K. Debanath

Advanced Materials Letters, 2018, Volume 9, Issue 7, Pages 494-498
DOI: 10.5185/amlett.2018.2066

In this study, we report the synthesis and optical properties of flower-shaped ZnO which is fabricated successfully using polyvinylpyrrolidone (PVP) as capping agent by wet chemical method at temperature 60 0 C. The structures and morphologies of flower-shaped ZnO is characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM) for nonlinear dynamical study of the system of particles. The studies of SEM and TEM have confirmed flower-shaped structure of the ZnO. The UV-vis absorption spectroscopy of the synthesized sample indicates the presence of blue shift. FTIR analysis shows the characteristic absorption of the Zn-O bond. It has been observed in room temperature photoluminescence (PL) spectroscopy of the sample exhibits emission peaks at near band edge (NBE) along with a weak blue emission peak. It is found from the present study that the phenomenon of flower-like microstructure is based on the size and shape of the particles as well as their aggregated forms. Moreover, their optical properties predict the factors responsible in inhibiting microorganisms for which it may lead to some biological applications. 

Effect of graphite nanosheets on electrical, electromagnetic, mechanical and morphological characteristics of PHBV/GNS nanocomposites  

Larissa S. Montagna; Thaís L. do A. Montanheiro; Maurício R. Baldan; Ana Paula S. Oliveira; Marcelo A. de Farias; Marcele A. Hocevar; Luiza C. Folgueras; Fábio R. Passador; Ana Paula Lemes; Mirabel C. Rezende

Advanced Materials Letters, 2018, Volume 9, Issue 7, Pages 499-504
DOI: 10.5185/amlett.2018.2044

Bionanocomposites with properties similar to those of conventional polymers derived from petroleum have shown scientific and industrial interest. The current research discuss the effect of graphite nanosheets (GNS) addition on electrical, electromagnetic, and mechanical properties and also on morphological aspects of the natural polymer poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV)/GNS nanocomposites and neat PHBV prepared by casting method. Nanocomposite of PHBV/1.00 wt% GNS showed good electrical conductivity values, extending the scope of application of these materials, such as in reflectors. One of the objectives of this study was to investigate the effect of different contents of GNS in neat PHBV using dynamic mechanical analysis (DMA), which showed that the addition of GNS in PHBV matrix improved the DMA properties. Transmission electron microscopy (TEM) shows good dispersion of GNS in the PHBV matrix with stacked and intercalated graphite layers and XPS confirmed the presence of carbon and oxygen in the graphite nanosheets surface.

Thermal properties of hydrogel-clay nano-composites

Romina P. Ollier*; Jimena S. Gonzalez;Vera A. Alvarez; Laura M. Sanchez

Advanced Materials Letters, 2018, Volume 9, Issue 7, Pages 505-509
DOI: 10.5185/amlett.2018.2047

Hydrogels are one of the most widely employed materials in biological, medical and technological areas. However, the use of hydrogels sometimes is restricted due to their specific properties. It is well-known that polymeric nanocomposites reinforced with clays show valuable improvements in their properties. In this work, eco-friendly composite hydrogels were prepared employing polyvinylalcohol (PVA) and bentonite (abundant and low cost smectite-type clay in Argentina) as raw materials through the previously optimized freezing-thawing (F-T) crosslinking method. Different nanocomposite hydrogels were obtained by varying the corresponding reactor feed. These materials have been recently chemically, morphologically and mechanically analysed in a recent work. Specifically, in the present work, thermal degradation behaviour of PVA-bentonite hydrogels was studied. Kinetic analytical models were applied to non-isothermal thermogravimetric (TGA) measurements trying to identify the possible mechanism for PVA degradation in the presence of bentonite.

Experimental investigation of oxidation resistance of SiC powder for the protection of re-entry space vehicle using material shock tube 

Jayaram Vishakantaiah; Gowtham Balasubramaniam

Advanced Materials Letters, 2018, Volume 9, Issue 7, Pages 510-515
DOI: 10.5185/amlett.2018.2061

A novel method of studying oxidation resistance and phase transformation of SiC fine powder was performed using multiple shock treatments in millisecond timescale using indigenously developed material shock tube (MST1). MST1 was used to produce shock waves which heat the ultra high pure oxygen test gas to a reflected shock temperature and pressure of about 5300 K (estimated) and 25 bar, respectively for 1-2 milliseconds. Different characterization techniques like X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) show the formation of oxides and sub-oxide species after shock treatment. XRD studies shows the phase transformation of hexagonal SiC to amorphous SiO2. SEM and TEM micrographs show change in surface morphology of SiC from irregular shape to micro/nano spheres due to superheating and cooling at the rate of about 106 K/s. This novel method is used  for the first time to demonstrate the behavior of material in presence of extreme aero-thermodynamic conditions for a short duration. These conditions generated using shock tubes are not achievable by conventional furnaces for oxidation studies of SiC in a short duration.

Functionalized graphene oxide as an electrochemical sensing platform for detection of Bisphenol A

Upama Baruah;Devasish Chowdhury

Advanced Materials Letters, 2018, Volume 9, Issue 7, Pages 516-525
DOI: 10.5185/amlett.2018.2067

The present work demonstrates the electrochemical detection of the endocrine disruptor Bisphenol A in solution by three different types of functionalized graphene samples viz. graphene oxide (GO), ester functionalized graphene oxide (GO-ES) and amine functionalized graphene oxide (GO-en) modified glassy carbon electrode (GCE) using a very simple drop casting method without the use of any toxic organic compounds or polymeric binders via cyclic voltammetry. The system developed showed detection of BPA via formation of a π-stacked layered functionalized graphene oxide-BPA (π-s-GO-BPA) nanocomposite accompanied by a reduction in the oxidation peak current value associated with a significant shift in the peak potential value. The electrochemical sensing materials developed showed good sensitivity compared to already reported systems and furthermore high selectivity in presence of other structurally similar kinds of molecules in solution without the use of any toxic organic chemicals thereby demonstrating the practical applicability of the material and the technique developed. The practical viability of the material developed is also demonstrated via testing with a real low quality plastic sample that contains Bisphenol A. A plausible mechanism to justify the detection process is also being discussed. 

Polyacrylamide-scaffold adhesive bearing multiple benzene rings forming CH/π  interactions with polyolefin

Taiki Yamate; Hiroshi Suzuki; Takayuki Fujiwara; Toru Yamaguchi; Motohiro Akazome

Advanced Materials Letters, 2018, Volume 9, Issue 7, Pages 526-530
DOI: 10.5185/amlett.2018.2055

Adhesion to chemically inert materials (CIM) through non-covalent interactions without surface modifications represents a formidable challenge in adhesion science. We report herein a rigid poly(acrylamide) bearing multiple benzene rings in its side chains that can strongly adhere to the chemically inert surface of the polyolefin without the need for surface modifications. This adhesive is rationally designed based on our previous findings. The adhesion to polyolefin is triggered by the formation of multiple CH/p < /span> interactions at the macroscopic interface. The adhesion strength is far greater than that of adhesions using surface modifications or commercially available polyolefin adhesives. In this study, the adhesion mechanism is carefully analyzed by experimental and theoretical studies. We anticipate that this study could address the long-standing issue of achieving strong adhesion to CIMs without requiring surface modifications and pave the way for future research into the development of new adhesives for CIMs. 

Uptake and toxicity of different nanoparticles towards a tough bacterium: Deinococcus radiodurans

Ragini Singh;Sanjay Singh

Advanced Materials Letters, 2018, Volume 9, Issue 7, Pages 531-537
DOI: 10.5185/amlett.2018.2064

Nanomaterials (NMs) have found extensive commercial use in industries, healthcare and household applications however, their ecotoxicological effects remain elusive. Since, microbial communities play beneficial role in ecosystem like element cycling, bioremediation, nitrogen fixation, etc., effect of NMs over beneficial microbe’s physiology and viability remains to be studied in detail. Some beneficial microbe communities are severely affected by the release of NMs in the environment. Deinococcus radiodurans is known for its tolerance to oxidative stress caused due to irradiation. In this study, we have used metal, metal oxides, quantum dots (QDs) and carbon based NMs to assess their effect on the cell viability, uptake and ROS generation in D. radiodurans cells. The present study demonstrates in real-time by flow cytometry the internalization of different metal, metal oxide, QDs and carbon based NMs in D. radiodurans. Results show that all the tested NMs are significantly internalized in to the bacterial cells however, carbon based NMs exhibited highest internalization. Toxicity studies revealed that AgNPs exhibited maximum toxicity and reactive oxygen species (ROS) generation followed by QDs, CuO NPs and GO but, AuNPs and TiO2 NPs shows no toxic response in bacterial cells. The oxidative stress and uptake studies will provide insight about the mechanism of oxidative stress tolerance of D. radiodurans.