scholarly journals Tailorable Synthesis of Highly Oxidized Graphene Oxides via an Environmentally-Friendly Electrochemical Process

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 239 ◽  
Author(s):  
Ana María Díez-Pascual ◽  
Carlos Sainz-Urruela ◽  
Cristina Vallés ◽  
Soledad Vera-López ◽  
María Paz San Andrés
Keyword(s):  
Electrical Resistance ◽  
Interlayer Spacing ◽  
Electrochemical Process ◽  
Attractive Alternative ◽  
Mechanical And Thermal Properties ◽  
Graphene Oxides ◽  
Synthesis Conditions ◽  
Oxidation Level ◽  
Wide Range ◽  
Ft Ir

Graphene oxide (GO) is an attractive alternative to graphene for many applications due to its captivating optical, chemical, and electrical characteristics. In this work, GO powders with a different amount of surface groups were synthesized from graphite via an electrochemical two-stage process. Many synthesis conditions were tried to maximize the oxidation level, and comprehensive characterization of the resulting samples was carried out via elemental analysis, microscopies (TEM, SEM, AFM), X-ray diffraction, FT-IR and Raman spectroscopies as well as electrical resistance measurements. SEM and TEM images corroborate that the electrochemical process used herein preserves the integrity of the graphene flakes, enabling to obtain large, uniform and well exfoliated GO sheets. The GOs display a wide range of C/O ratios, determined by the voltage and time of each stage as well as the electrolyte concentration, and an unprecedented minimum C/O value was obtained for the optimal conditions. FT-IR evidences strong intermolecular interactions between neighbouring oxygenated groups. The intensity ratio of D/G bands in the Raman spectra is high for samples prepared using concentrated H2SO4 as an electrolyte, indicative of many defects. Furthermore, these GOs exhibit smaller interlayer spacing than that expected according to their oxygen content, which suggests predominant oxidation on the flake edges. Results point out that the electrical resistance is conditioned mostly by the interlayer distance and not simply by the C/O ratio. The tuning of the oxidation level is useful for the design of GOs with tailorable structural, electrical, optical, mechanical, and thermal properties.

scholarly journals Synthesis and characterization of polystyrene sulfonic acid-polyaniline and montmorillonite nanocomposites

2016 ◽  
Vol 4 (2) ◽  
pp. 36
Author(s):  
Kugamoorthy Velauthamurty ◽  
Vamadevan Akileshan
Keyword(s):  
Thermal Stability ◽  
Sulfonic Acid ◽  
Oxidative Polymerization ◽  
Interlayer Spacing ◽  
Research Field ◽  
Mechanical And Thermal Properties ◽  
Gravimetric Analysis ◽  
Aniline Monomer ◽  
Wide Range ◽  
Polystyrene Sulfonic Acid

Numerous polymer ingredients merged montmorillonite (MMT) has received a great deal of attention in the research field of clay-polymer nanocomposites, due to the enhancements in physical properties such as mechanical and thermal properties compared to their parent materials. MMT-polyaniline-polystyrene sulfonic acid nanocomposites containing different amounts of PANI and PSSA were prepared by the interaction of aniline monomer into pristine MMT together with cation intercalated MMT. It is followed by the subsequent oxidative polymerization of the aniline and PSSA in the interlayer spacing to give MMT-PANI-PSSA nanocomposites. X-Ray diffraction and Fourier-transform infrared spectroscopy results confirmed that PANI and PSSA have been inserted within the MMT interlayer. Thermal Gravimetric Analysis (TGA) shows that the improved thermal stability for the intercalated nanocomposites in comparison with the PANI clay nanocomposites. The thermal behavior of MMT-PANI-PSSA nanocomposites is analyzed in a wide range of temperatures. TGA analysis suggests that the PSSA-PANI of ratio 3:2 is thermally stable. Cyclic votlammogams of the PSSA-PANI- Ce(III) -MMT shows characteristic redox behavior of that appear in the Ce(IV)/Ce(III) under identical conditions together with the typical electrochemical behavior of PSSA. These prepared nanocomposites have several advantages over the other PSSA-MMT nanocomposites such as lesser sheet resistance, advanced hardness and improved thermal stability.

Study of the Influence of Different Synthesis Conditions of PANI-HF in its Property as Ammonia Gas Sensor

2012 ◽  
Vol 727-728 ◽  
pp. 1666-1670
Author(s):  
Glaucea Warmeling Duarte ◽  
C.G. Tachinski ◽  
A.M. Naspolini ◽  
E.C. Consenso ◽  
F.Z. Silveira ◽  
...  
Keyword(s):  
Air Pollution ◽  
Chemical Synthesis ◽  
Electrical Resistance ◽  
Room Temperature ◽  
Electronic Devices ◽  
Ammonia Gas ◽  
Gas Concentration ◽  
Synthesis Conditions ◽  
Wide Range ◽  
Protonic Acids

ntrinsically Conducting Polymers (ICPs) are of increasing interest, especially in areas such as electronic devices. PANI is one of the most intensively investigated of the ICPs due to its easy chemical synthesis, easy doping process by protonic acids and also because it is chemically stable at room temperature conditions. PANI is used as sensor for many gases that are responsive for air pollution The applicability of these materials as sensors is based on their selectivity over a wide range of analyte molecules and low level of gas concentration, the potential to operate at or near room temperature and also its response time. The present work studies the influence of different synthesis conditions of PANI-HF in its electrical resistance when subjected to the presence of ammonia gas. The PANI-HF was chemically synthesized and it was submitted to electrical and physical characterization. The preview results showed that the synthesis conditions change significantly the response of PANI-HF to ammonia gas.

scholarly journals Opoka—Sediment Rock as New Type of Hybrid Mineral Filler for Polymer Composites

AppliedChem ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 90-110
Author(s):  
Robert E. Przekop ◽  
Paulina Jakubowska ◽  
Bogna Sztorch ◽  
Rafał Kozera ◽  
Kamil Dydek ◽  
...  
Keyword(s):  
Nitrogen Adsorption ◽  
Physicochemical Characteristics ◽  
Attractive Alternative ◽  
Melt Blending ◽  
Hybrid Filler ◽  
Widespread Occurrence ◽  
Polypropylene Composites ◽  
Wide Range ◽  
New Type ◽  
Ft Ir

The work presents a comprehensive profile of the physicochemical characteristics of opoka sedimentary rock in the context of its use as a hybrid filler for thermoplastics. Determining the functional parameters of the studied filler was the main aim of this research. Thermal treatment leads to changes in its morphology and phase composition. A wide range of physicochemical techniques was used, such as low-temperature nitrogen adsorption, FT-IR, TGA, XRD, optical, and electron microscopy. The susceptibility of the material to micronisation was also tested (ball milling). Due to its widespread occurrence, opoka can be an attractive alternative to fillers such as silica or chalk. In order to verify this statement, polypropylene composites thereof were prepared by melt blending and injection molding, and studied by mechanical testing and microscopic imaging.

scholarly journals Graphene Oxides Derivatives Prepared by an Electrochemical Approach: Correlation between Structure and Properties

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2532
Author(s):  
Carlos Sainz-Urruela ◽  
Soledad Vera-López ◽  
María San Andrés ◽  
Ana Díez-Pascual
Keyword(s):  
Mechanical Properties ◽  
Interlayer Spacing ◽  
Complete Characterization ◽  
Raw Material ◽  
Structure Property ◽  
Graphene Oxides ◽  
Structure Property Relationships ◽  
Electrochemical Approach ◽  
Wide Range ◽  
Defect Content

Graphene oxide (GO) can be defined as a single monolayer of graphite with oxygen-containing functionalities such as epoxides, alcohols, and carboxylic acids. It is an interesting alternative to graphene for many applications due to its exceptional properties and feasibility of functionalization. In this study, electrochemically exfoliated graphene oxides (EGOs) with different amounts of surface groups, hence level of oxidation, were prepared by an electrochemical two-stage approach using graphite as raw material. A complete characterization of the EGOs was carried out in order to correlate their surface topography, interlayer spacing, defect content, and specific surface area (SSA) with their electrical, thermal, and mechanical properties. It has been found that the SSA has a direct relationship with the d-spacing. The EGOs electrical resistance decreases with increasing SSA while rises with increasing the D/G band intensity ratio in the Raman spectra, hence the defect content. Their thermal stability under both nitrogen and dry air atmospheres depends on both their oxidation level and defect content. Their macroscopic mechanical properties, namely the Young’s modulus and tensile strength, are influenced by the defect content, while no correlation was found with their SSA or interlayer spacing. Young moduli values as high as 54 GPa have been measured, which corroborates that the developed method preserves the integrity of the graphene flakes. Understanding the structure-property relationships in these materials is useful for the design of modified GOs with controllable morphologies and properties for a wide range of applications in electrical/electronic devices.

The effect of carbon nanotubes-grafted lactide on the mechanical and thermal properties of poly (lactic acid) biocomposites

2017 ◽  
Vol 36 (9) ◽  
pp. 655-666 ◽  
Author(s):  
Gaihong Wu ◽  
Shuqiang Liu ◽  
Xiongying Wu ◽  
Xuemei Ding
Keyword(s):  
Carbon Nanotubes ◽  
Lactic Acid ◽  
Thermal Properties ◽  
Composite Films ◽  
Poly Lactic Acid ◽  
Mechanical And Thermal Properties ◽  
Wide Range ◽  
Ft Ir ◽  
The Fourier Transform ◽  
Flexible Fabrication

Poly(lactic acid) (PLA) derived from renewable crops is a promising substitute for petroleum-based products. Although PLA exhibits positive features, it also possesses drawbacks, such as brittleness, which hinder its extension in specific applications. In this study, lactide (LA) was used to graft carbon nanotubes (CNTs) to reinforce PLA. Under catalysis, LA was polymerized into PLA through ring-opening polymerization and simultaneously was grafted onto CNTs to obtain CNTs modified by LA (LA/CNTs). And the modified CNTs were used to prepare PLA composite films (LA/CNTs/PLA). Analysis of the Fourier transform infrared spectra (FT-IR) of the modified CNTs indicated that LA was grafted with the nanotubes. The scanning electron microscopy images showed that the modified CNTs were compatible and homogeneously dispersed in the PLA matrix. The excellent dispersibility and compatibility of the CNTs led to good interfacial adhesion, which directly enhanced the mechanical properties of PLA. The addition of CNTs also improved the thermal properties of PLA. This research aims to ameliorate the mechanical and thermal properties of PLA and provides basis for flexible fabrication of bio-based PLA materials for a wide range of applications.

scholarly journals Multidimensional Ln-Aminophthalate Photoluminescent Coordination Polymers

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1786
Author(s):  
Carla Queirós ◽  
Chen Sun ◽  
Ana M. G. Silva ◽  
Baltazar de Castro ◽  
Juan Cabanillas-Gonzalez ◽  
...  
Keyword(s):  
Water Content ◽  
Coordination Polymers ◽  
Metal Ion ◽  
Low Cost ◽  
Microwave Assisted Synthesis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wide Range ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

The development of straightforward reproducible methods for the preparation of new photoluminescent coordination polymers (CPs) is an important goal in luminescence and chemical sensing fields. Isophthalic acid derivatives have been reported for a wide range of applications, and in addition to their relatively low cost, have encouraged its use in the preparation of novel lanthanide-based coordination polymers (LnCPs). Considering that the photoluminescent properties of these CPs are highly dependent on the existence of water molecules in the crystal structure, our research efforts are now focused on the preparation of CP with the lowest water content possible, while considering a green chemistry approach. One- and two-dimensional (1D and 2D) LnCPs were prepared from 5-aminoisophthalic acid and Sm3+/Tb3+ using hydrothermal and/or microwave-assisted synthesis. The unprecedented LnCPs were characterized by single-crystal X-ray diffraction (SCRXD), powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM), and their photoluminescence (PL) properties were studied in the solid state, at room temperature, using the CPs as powders and encapsulated in poly(methyl methacrylate (PMMA) films, envisaging the potential preparation of devices for sensing. The materials revealed interesting PL properties that depend on the dimensionality, metal ion, co-ligand used and water content.

Accelerating the optimization of enzyme-catalyzed synthesis conditions via machine learning and reactivity descriptors

2021 ◽  
Author(s):  
Zhongyu Wan ◽  
Quan-De Wang ◽  
Dongchang Liu ◽  
Jinhu Liang
Keyword(s):  
Machine Learning ◽  
Optimal Synthesis ◽  
Human Knowledge ◽  
Crucial Importance ◽  
Reactivity Descriptors ◽  
Synthesis Conditions ◽  
Wide Range ◽  
Synthesis Reactions ◽  
Selection Of

Enzyme-catalyzed synthesis reactions are of crucial importance for a wide range of applications. An accurate and rapid selection of optimal synthesis conditions is crucial and challenging for both human knowledge...

NOHSO4/HF – A Novel Etching System for Crystalline Silicon

2007 ◽  
Vol 62 (11) ◽  
pp. 1411-1421 ◽  
Author(s):  
Sebastian Patzig ◽  
Gerhard Roewer ◽  
Edwin Kroke ◽  
Ingo över
Keyword(s):  
Gas Phase ◽  
Chemical Etching ◽  
Silicon Surface ◽  
Crystalline Silicon ◽  
Etching Solution ◽  
Wide Range ◽  
Ft Ir ◽  
Wet Chemical ◽  
Wet Chemical Etching ◽  
Etching System

Solutions consisting of HF - NOHSO4 - H2SO4 exhibit a strong reactivity towards crystalline silicon which is controlled by the concentrations of the reactive species HF and NO+. Selective isotropic and anisotropic wet chemical etching with these solutions allows to generate a wide range of silicon surface morphology patterns. Traces of Ag+ ions stimulate the reactivity and lead to the formation of planarized (polished) silicon surfaces. Analyses of the silicon surface, the etching solution and the gas phase were performed with scanning electron microscopy (SEM), DR/FT-IR (diffusive reflection Fourier transform infra-red), FT-IR, Raman and NMR spectroscopy, respectively. It was found that the resulting silicon surface is hydrogen-terminated. The gas phase contains predominantly SiF4, NO and N2O. Furthermore, NH4+ is produced in solution. The study has confirmed the crucial role of nitrosyl ions for isotropic wet chemical etching processes. The novel etching system is proposed as an effective new way for selective surface texturing of multi- and monocrystalline silicon. A high etching bath service lifetime, besides a low contamination of the etching solution with reaction products, provides ecological and economical advantages for the semiconductor and solar industry.

Effects of ultra-high pressures (>3.6 GPa) on the electrical resistance of polyaniline by in situ FT-IR studies

1997 ◽  
Vol 280 (5-6) ◽  
pp. 469-474 ◽  
Author(s):  
Xing-Rong Zeng ◽  
Ke-Cheng Gong ◽  
Ke-Nan Weng ◽  
Wan-Sheng Xiao ◽  
Wen-Hong Gan ◽  
...  
Keyword(s):  
Electrical Resistance ◽  
High Pressures ◽  
Ir Studies ◽  
Ft Ir

scholarly journals Characterization of the Physical, Chemical, and Adsorption Properties of Coal-Fly-Ash–Hydroxyapatite Composites

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 774
Author(s):  
Eleonora Sočo ◽  
Dorota Papciak ◽  
Magdalena M. Michel ◽  
Dariusz Pająk ◽  
Andżelika Domoń ◽  
...  
Keyword(s):  
Fly Ash ◽  
Coal Fly Ash ◽  
Thermal Power ◽  
Synthesis Conditions ◽  
High Calcium ◽  
Ft Ir ◽  
Ir Analysis ◽  
Wet Synthesis

(1) Hydroxyapatite (Hap), which can be obtained by several methods, is known to be a good adsorbent. Coal fly ash (CFA) is a commonly reused byproduct also used in environmental applications as an adsorbent. We sought to answer the following question: Can CFA be included in the method of Hap wet synthesis to produce a composite capable of adsorbing both heavy metals and dyes? (2) High calcium lignite CFA from the thermal power plant in Bełchatów (Poland) was used as the base to prepare CFA–Hap composites. Four types designated CFA–Hap1–4 were synthesized via the wet method of in situ precipitation. The synthesis conditions differed in terms of the calcium reactants used, pH, and temperature. We also investigated the equilibrium adsorption of Cu(II) and rhodamine B (RB) on CFA–Hap1–4. The data were fitted using the Langmuir, Freundlich, and Redlich–Peterson models and validated using R2 and χ2/DoF. Surface changes in CFA–Hap2 following Cu(II) and RB adsorption were assessed using SEM, SE, and FT-IR analysis. (3) The obtained composites contained hydroxyapatite (Ca/P 1.67) and aluminosilicates. The mode of Cu(II) and RB adsorption could be explained by the Redlich–Peterson model. The CFA–Hap2 obtained using CFA, Ca(NO3)2, and (NH4)2HPO4 at RT and pH 11 exhibited the highest maximal adsorption capacity: 73.6 mg Cu/g and 87.0 mg RB/g. (4) The clear advantage of chemisorption over physisorption was indicated by the Cu(II)–CFA–Hap system. The RB molecules present in the form of uncharged lactone were favorably adsorbed even on strongly deprotonated CFA–Hap surfaces.

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