Showing papers in "Journal of Inorganic and Organometallic Polymers and Materials in 2016"

Synthesis, Structural and Optical Characterization of MgO Nanocrystalline Embedded in PVA Matrix

Abstract: Nano-magnesium oxide (MgO) was prepared by wet chemical method using magnesium chloride and sodium hydroxide as precursors and soluble gelatin as stabilizing agent in this paper. The synthesized nano MgO was characterized by XRD, SEM, and FTIR. The results showed that the size of nano-MgO was about 20.62 nm. Polyvinyl alcohol (PVA) polymer based nanocomposites, with different concentrations of MgO (1, 2, 3, 4 wt%), have been prepared using solvent casting technique. The results of SEM revealed that the MgO nanoparticles are uniformly distributed in PVA polymer matrix. FTIR analysis evidently saw the interaction between MgO with hydroxyl group of PVA through hydrogen bonding. The influences of MgO nanoparticle on the optical characterisation of PVA have been considered using UV–Vis–NIR spectroscopy. Energy band gap and tail of localized state of PVA/MgO nanocomposites have been calculated by using Tauc and Urbach relations, respectively. The band gap of the nanocomposites samples decreases as MgO wt% increases. Wemple-DiDomenico single-oscillator model has been applied to analyze the dispersion of the refractive index of the films, and the dispersion parameters are calculated to obtain the information about disorder degree.

Carbon Nanotubes (CNTs) Nanocomposite Hydrogels Developed for Various Applications: A Critical Review

Abstract: Interest in the development of polymeric hydrogels impregnated with carbon-nanotubes (CNTs) is growing rapidly in recent times owing to their usefulness in many fields of human endeavor. This review paper serves as an archive of literature reports of several researchers who have worked on polymeric hydrogels embedded with CNTs for diverse applications. The review covers up to date research advancement on the synthesis and characterization properties of CNTs nanocomposite hydrogels. Besides, this review discusses extensively the various fields in which polymeric hydrogels infused with CNTs have been applied. This unprecedented compilation of CNTs nanocomposite hydrogels information into a single revision allows a straightforward comparison of studies performed for diverse applications.

Carbon Nanotube: Synthesis and Application in Solar Cell

Abstract: Carbon nanotubes and fullerenes have a cylindrical and hollow spherical molecular structure with outstanding mechanical and electronic properties. Their versatility is outstanding and envisioned by the wide application range from field emission displays to impregnated metal composites, battery storage media, and nano-electronic devices. The combination of simple materials, diverse behavior, and ease of fabrication make these materials a cornerstone topic in current research. They have very wide applications in electronic devices and identifying the potential applications which is due to low bias transport at several nanometers. Since valance and conduction bands are symmetric, so they have a direct band gap and due to this it can be used in optical emission. CNTs can be synthesized via three techniques such as arc discharge, laser ablation and chemical vapor deposition, but the CVD process is mainly used for the synthesis because the CNT yield in such case will be more than 98 % pure. 100 % pure MWCNTs having multiple chirality results the enhanced optical property and better employment as light harvesting material. The dye sensitized solar cells are fabricated using CNT composites and functionalized nanotubes. The synthesis of CNT and its application in solar cell are presented in this short review.

MWCNT Doped ZnO Nanocomposite Thin Film as LPG Sensing

Abstract: A compound material of multi-walled carbon nanotubes (MWCNTs) coated with ZnO was synthesized at ambient conditions. The X-ray diffraction, UV–visible spectroscopy, scanning electron microscope (SEM) and transmission electron microscopy results confirmed that the existence of ZnO nanoparticles inside the MWCNTs. The gas sensing properties of the material were studied. ZnO-based composites on MWCNTs treated at room temperature shows enhanced performance as sensors, making them suitable for practical applications. Sensor structure showed a better sensing response (S ~61.57) at operating room temperature towards 1500 ppm LPG with an average sensitivity 41.95. Furthermore, the gas sensor responses increased linearly with the increment of the gas concentrations of LPG.

Investigation of Characterization and Mechanical Performances of Al2O3 and SiC Reinforced PA6 Hybrid Composites

Abstract: In this study, the influence of different weight percentages of alumina oxide (Al2O3) and silicon carbide (SiC) reinforcement on the mechanical properties of Polyamide (PA6) composite is investigated. Test specimens of pure PA6, 85 wt% PA6 + 10 wt% Al2O3 + 5 wt% SiC and 85 wt% PA6 +10 wt% SiC + 5 wt% Al2O3 are prepared using an injection molding machine. To investigate the mechanical behaviors tensile test, impact test, flexural test, and hardness test were conducted in accordance with ASTM standards. Experimental results indicated that the mechanical properties, such as tensile, impact, hardness, and flexural strength were considerably higher than the pure PA6. The tensile fracture morphology and the characterization of PA6 hybrid composites were observed by scanning electron microscope and Fourier transform infrared spectroscopic method. Further, thermogravimetric analysis confirms the thermal stability of PA6 hybrid composites. The reinforcing effects of Al2O3 and SiC on the mechanical properties of PA6 hybrid composites were compared and interpreted in this paper. Improved mechanical and thermal characteristics were observed by the addition of small amount of Al2O3 and SiC simultaneously reinforced with the pure PA6.

Fabrication of Polyaniline (PANI)—Tungsten oxide (WO 3 ) Composite for Humidity Sensing Application

Abstract: In this paper, PANI–WO3 composite was synthesized via chemical polymerization method. The results were well supported by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), UV–visible spectrophotometer and sensing measurements. The formation of PANI–WO3 was confirmed by XRD analysis. The average crystallite size was evaluated using Debye-Scherer’s formula. The functional group present in the PANI–WO3 was confirmed using FTIR spectrometer. UV–visible spectra showed the presence of different rings and energy band gaps of various samples were calculated. Further, the thin films of samples have been fabricated using spin coater. The sensing studies at 10, 20, 30 and 40 % of WO3 in PANI were carried out at room temperature. Sensing results demonstrate the fabricated porous PANI–WO3 composite thin films which is a challenging material for the development of the humidity sensors.

Preparation and Characterization of Novel Hybrid Nanocomposites by Free Radical Copolymerization of Vinyl pyrrolidone with Incompletely Condensed Polyhedral Oligomeric Silsesquioxane

Abstract: A new series of hybrid nanocomposites based on poly (vinyl pyrrolidone) (PVP) containing incompletely condensed polyhedral oligomeric silsesquioxane (IC-POSS) with different percentages of POSS were prepared via free radical copolymerization. Incompletely condensed, phenyl-POSS (Na3O12Si7(C6H5)7) with the highly reactive group of trisodium silanolate was used to prepare desire IC-POSS by nucleophilic substitution reaction. The products were characterized by Fourier transform infrared, X-ray diffraction, scanning electron microscopy, differential scanning calorimetry and thermogravimetric analysis techniques. The results of analysis confirmed that there are good interactions between IC-POSS and the PVP matrix. The thermal stability of the PVP was enhanced with the addition of small amounts of nano-filler. The solubility of the nanocomposites has been also tested and the results showed that with increasing the IC-POSS content the hydrophobicity of nanocomposites were increased.

Synthesis and Structural Characteristic of Platinum Nanoparticles Using Herbal Bidens Tripartitus Extract

Abstract: Application of biological organisms, such as microorganisms, plant extract or plant biomass, could be an alternative to chemical and physical methods of the synthesis of nanoparticles. Following this statement, the present work focused on conducting the synthesis of platinum nanoparticles using herbal Bidens tripartitus extract. The formed platinum nanoparticles were characterized by Ultraviolet–Visible, Fourier Transform-Infrared (FT-IR), scanning electron microscopy and EDS analyzer, transmission electron microscopy and atomic force microscopy (AFM) measurements. AFM analysis confirmed the presence of platinum nanoparticles with the size of 4 nm. In the FT-IR spectrum of B. tripartitus herbal extract, there were observed peaks characteristic of phenols. Also, herbal B. tripartitus extract is an effective medium for the synthesis of platinum nanoparticles.

DFT Studies on Interaction of H 2 S Gas with α-Fe 2 O 3 Nanostructures

Abstract: The structural stability, electronic properties and adsorption characteristics of H2S on pristine, Ag and Pd substituted α-Fe2O3 nanostructures are studied using density functional theory along with B3LYP/LanL2DZ basis set. The structural stability of α-Fe2O3 nanostructures are studied in terms of formation energy. The electronic properties of pristine, Ag and Pd substituted α-Fe2O3 nanostructures are studied with ionization potential, electron affinity and HOMO–LUMO gap. The adsorption properties of H2S on Fe2O3 are analyzed and the favorable adsorption sites are reported. The key parameters such as Mulliken population analysis, energy gap, adsorbed energy and average energy gap variation are used to identify the favorable site of H2S adsorption on Fe2O3. α-Fe2O3 nanostructure can be tailored with suitable substitution impurities to enhance the adsorption characteristics of H2S on Fe2O3 nanostructures in the mixed gas environment.

Synthesis, Characterization of Nickel Ferrite and Its Uses as Humidity and LPG Sensors

Abstract: Nanostructured nickel ferrites (sample B1 and B2) were synthesized by chemical precipitation method using two different precipitating agents; sodium and ammonium hydroxides. The samples were characterized by using powder X-ray diffraction, scanning and transmission electron microscopy techniques. The X-ray diffraction revealed the formation of nickel ferrite with lattice parameter a = 8.3 A and the average crystallite sizes of the samples B1 and B2 were 50 and 15 nm respectively. Surface morphology of the sample B2 exhibited the higher number of adsorption sites in comparison to B1. Transmissions electron microscopy observations confirmed the formation of nanostructured nickel ferrite. Further the pellets, thick and thin films of materials B1 and B2 were prepared and investigated with the exposition of humidity and LPG. Maximum average sensitivity for humidity was formed as 53.74 MΩ/%RH. Also the maximum value of sensitivity was found 62.3 for 4 vol% of LPG. The results were found to be reproducible up to 96 % after 3 months. Response and recovery times for LPG sensing were found to be 220 and 250 s. Best sensitivity, less hysteresis, small activation energy and good reproducibility identify that fabricated humidity and LPG sensors (B2) are promising and challenging.

Preparation of a Novel Nano-scale Lead (II) Zig-Zag Metal–Organic Coordination Polymer with Ultrasonic Assistance: Synthesis, Crystal Structure, Thermal Properties, and NBO Analysis of [Pb(μ-2-pinh)N3 H2O]n

Abstract: A novel nano-cauliflower-shaped lead(II) metal–organic coordination polymer, [Pb(μ-2-pinh)N3 H2O]n (1), was synthesized using an ultrasonic method. The nanostructure was characterized by scanning electron microscopy (SEM), X-ray powder diffraction, IR spectroscopy, elemental analysis, and thermal analysis. The compound was structurally characterized by single-crystal X-ray diffraction. The coordination compound takes the form of a zig-zag one-dimensional polymer in solid state. The coordination number of the lead(II) ions is six (PbN4O2) with three nitrogen atoms and one oxygen atom from two linker organic ligands, as well as one oxygen from coordinated water and one nitrogen atom from terminal coordinated azide anion. It has a stereo-chemically active lone electron pair, and the coordination sphere is hemidirected. The zig-zag 1D chains interact with neighbouring chains through weak interactions, creating a 3D supramolecular metal–organic framework. Lead oxide nanoparticles were obtained by thermolysis of the new nano coordination compound at 180 °C with oleic acid as a surfactant. The morphology and size were further studied using SEM. Natural bond orbital analyses demonstrate the electronic properties of the lead centre and other atoms.

Metal Chelate Monomers as Precursors of Polymeric Materials

Abstract: The principal advances and problems of the preparation of polymeric materials based on metal chelate monomers containing metal chelate cycle and functionality are analysed. The data are systematized according to methods for preparing polymeric materials: homopolymerization, copolymerization, living and controlled polymerization, grafting polymerization, electropolymerization, polycondensation, as well as synthesis of dendrimers and hyperbranched polymers based on metal chelate monomers. Special attention is paid to the effect of a metal on both the synthesis mechanism and properties of the products formed. The principal applications of polymeric materials based on metal chelate monomers are considered.

Solid State Synthesis of Hematite Nanoparticles from Doped Poly o -aminophenol (POAP)

Abstract: Poly o-aminophenol (POAP) was prepared by the oxidative polymerization of o-aminophenol with potassium dichromate as an oxidant. The results showed that o-amniophenol polymerizes in linear mode. The effect of doping CoCl2, NiCl2, MnCl2, FeCl3, and CuCl2 on the spectral, thermal and optical properties of POAP has been studied. The thermal stability of doped POAP differs from the pure POAP according to the doped ion. The optical band gaps of the doped POAP are smaller than the pure POAP. Fe doped POAP has been used as a precursor for hematite (α-Fe2O3) nanoparticles by thermal decomposition route. The obtained (α-Fe2O3) nanoparticles have been characterized by XRD and HRTEM. The average size of the prepared nanoparticles was estimated as 53 nm. The optical band gap of the obtained α-Fe2O3 is larger than the bulk.

Sonochemical Synthesis, Characterization and Sonocatalytic Performance of Terbium-Doped CdS Nanoparticles

Abstract: Terbium-doped cadmium sulfide nanoparticles with different terbium contents were successfully synthesized via sonochemical route. The prepared samples were characterized by X-ray diffraction, scanning electron microscopy, photoelectron X-ray spectroscopy, and UV–Vis diffuse reflectance spectroscopy techniques. The as-prepared nanocatalyst were used for sonocatalytic degradation of Methylene Blue. Among the different amounts of dopant, 8 % Tb-doped CdS showed the highest sonocatalytic activity. The order of inhibitory effect of radical scavengers was 1, 4 Benzoquinone > SO3 2− > CO2 3−> I−. The effects of various parameters such as initial dye concentration, catalyst loading, ultrasonic power, and the presence of radical scavengers were investigated.

One-Step Fabrication of Magnetic Carbon Nanocomposite as Adsorbent for Removal of Methylene Blue

Abstract: Magnetic Fe3O4@C nanocomposites with well-defined core@shell structure were synthesized via a facile one-step solvothermal process using ferrocene as both iron and carbon resource in the presence of hydrogen peroxide (H2O2). The as-prepared Fe3O4@C nanocomposites were employed as adsorbent materials for removal of methylene blue (MB) from aqueous solution. Several experimental parameters, including contact time, acidity of the solution, and initial MB concentration were investigated. The result showed that the equilibrium uptake of MB was related to the MB initial concentration as well as acidity of the solution. The adsorption kinetics of MB was dominated by the pseudo-second order reaction model. Significantly, the synthesized Fe3O4@C nanocomposites could be easily isolated from the adsorption system after adsorbing MB and showed prominent reusability. All results indicated that the prepared Fe3O4@C composites had the potential to be used as adsorbents for the removal of dye pollutant from wastewater.

Various Methods for Synthesis of Bulk and Nano Thallium(III) Oxide

Abstract: Thallium(III) oxide, a degenerate n-type semiconductor, is a highly insoluble thermally stable thallium source suitable for glass, optic and ceramic applications. Although thallium oxide is an important metal oxide, its synthesis has only been sporadically studied. This review gives an overview of all reported synthetic routes for the preparation of both bulk and nanostructured thallium(III) oxide. These methods include electrochemical methods, thermal method, chemical vapor deposition (CVD), microwave irradiation, sol–gel method and one recently chemical route using potassium superoxide. In electrochemical methods, both bulk and nanostructures of thallium(III) oxide can be prepared and the amount of the deposited material, thickness of the layer or wires length depends on the deposition time matrix structure. Thermal methods are simple and effective techniques which include thermal decomposition and calcination of various precursors. By CVD and microwave irradiation we be able to synthesis bulk and nanostructures of thallium(III) oxide, respectively. A one-step, room temperature, solution synthesis of thallium(III) oxide nanoparticles with a size of about 10 nm is reported by using potassium superoxide.

Polymer Protected and Gel Immobilized Gold and Silver Nanoparticles in Catalysis

Abstract: This mini-review is focused on preparation of polymer protected gold (AuNPs) and silver (AgNPs) nanoparticles that are immobilized on the surface of inorganic supporters and within hydrogel and/or cryogel matrices. A series of water soluble polymers such as poly(N-vinylpyrrolidone), poly(acrylic acid), branched polyethyleneimine, and amphoteric cryogel based on the copolymer of N,N-dimethylaminoethylmethacrylate and methacrylic acid poly(DMAEM-MAA) were used for reduction and stabilization of metal nanoparticles. The catalytic properties of polymer protected AuNPs and AgNPs were evaluated with respect to hydrogen peroxide decomposition, hydrogenation of 4-nitrophenol and oxidation of cyclohexane.

Nanoparticles of Magnetite in Polymer Matrices: Synthesis and Properties

Abstract: This review covers publications on magnetite nanoparticles in polymer matrix, especially in humic acids, which are very interesting, widespread natural polymers. Of special attention was the influence of synthetic conditions on the structure and physicochemical properties of magnetic nanomaterials as well as their potential in environmental applications as sorbents. Nanoparticles of Fe3O4 in polymer matrix as promising materials for environmental applications have been in the focus of a great number of studies due to their properties. The modification of magnetic nanoparticles by humic acids leads to increase the sorption properties of such composites and stabilization of magnetite nanoparticles, inhibiting their agglomeration. Thus, humic acids on the one hand, can be used as effective stabilizers for magnetoactive nanoparticles, and on the other hand, keep their protective properties towards ecotoxicants.

Preparation and Properties of Nanostructured PANI Thin Film and Its Application as Low Temperature NO2 Sensor

Abstract: Present work reports the preparation, properties of polyaniline (PANI) thin film and its application as NO2 gas sensor opertable at room temperature. PANI was successfully synthesized via chemical oxidative polymerization technique using aniline as a monomer and ammonium persulphate (APS) as oxidant. PANI thin film sensor was fabricated on corning glass substrate using spin coating technique. The film was characterized by XRD, TEM, SEM, FTIR and UV–Visible. The PANI film was found to give maximum sensing response of ~12.10 towards 100 ppm NO2 gas having with fast response and recovery times as ~11 s and 7 min.

Preparation of Bi2MoO6 Nanomaterials and Theirs Gas-Sensing Properties

Abstract: Bi2MoO6 nanomaterials are synthesized by a facile solvothermal method. Morphology and structure of the Bi2MoO6 nanomaterials are analyzed by SEM, XRD, N2 adsorption techniques and XPS. Gas-sensing properties of the as-prepared Bi2MoO6 sensors are also systematically investigated. The results show the Bi2MoO6 nanomaterials consist of nanosheets and demonstrate good crystallinity. The optimal operating temperature of the Bi2MoO6 sensors is 240 °C. At this operating temperature, The Bi2MoO6 sensor exhibits a fast response-recovery to ethanol, suggesting its excellent potential application as a gas sensor for ethanol gas-sensing applications.

Photocatalytic Decolorization of Dye Effluent Using Radiation Developed Polymeric Nanocomposites

Abstract: In this study [acrylic acid/p(N-vinyl-2-pyrrolidone)] (AAc/PVP) hydrogel was prepared using gamma irradiation technique. The prepared hydrogel was used as a template for in situ preparation of ZnO photocatalyst up to three deposition cycles. The structure, the thermal property, and the surface morphology of (AAc/PVP/ZnO) nanocomposite were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), transmission electron microscope (TEM) and scanning electron microscope (SEM) techniques. The photocatalytic activity of the obtained nanocomposite was tested for the degradation of methyl blue dye (MB) in the aqueous medium using UV-light. The effect of operational parameters on the degradation of MB such as UV irradiation time, pH, and initial dye concentration were examined. It was found that complete decolorization of MB dye was achieved after 45 min at pH 4. The degradation rate fitted the pseudo-first-order model and the rate of the photocatalytic reaction of the first preparation cycle of ZnO was higher than that of the third preparation cycle.

Designs of 3-Dimensional Networks and MOFs Using Mono- and Polymetallic Copper(I) Secondary Building Units and Mono- and Polythioethers: Materials Based on the Cu–S Coordination Bond

Abstract: This mini-review surveys 23 structures of 3D coordination polymers built upon mono-, di- as well as cyclic and acylic polythioethers. An emphasis is put on the Secondary Building Units (SBU) and the physical properties. Importantly, the key feature is that the dominant SBU is not the rhomboid (Cu2X2S4), but an inorganic polymer containing at least the chain of the type (CuX) n . In the latter type of SBU, these chain formations are observed for X = I, but predominantly for X = CN. In addition, a large portion of the surveyed materials exhibit rich photophysical properties, but on several occasions, these materials exhibit properties often attributed to MOFs, mainly solvent exchange.

Enhanced Photocatalytic Activity of BiOCl Hybridized with g-C3N4

Abstract: A g-C3N4/bismuth oxychloride (BiOCl) heterojunction was prepared by ultrasonic method. The microstructure, morphology, properties, and photocatalytic activity of the heterojunction were characterized using X-ray diffraction, UV–Vis diffuse reflection spectroscopy, field emission scanning electron microscopy, Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy and electro-chemical experiments. After hybridized with g-C3N4, the absorption edge of g-C3N4/BiOCl showed a red shift that reached 440 nm, with a band gap (E g) calculated to be 2.82 eV. Under visible-light irradiation, the hybrid photocatalyst also showed activity for methylene-blue photodegradation that was approximately 6.3 times higher than the activity of pure BiOCl. The mechanism of photocatalytic activity enhancement involved increased separation of electrons and holes between g-C3N4 and BiOCl. This work significantly contributed to the improvement in photocatalytic activity of BiOCl.

Cheap Synthesis, Characterization and Antibacterial Efficacy of New Copoly(o-Nitroaniline-co-o-Phenylenediamine) Emeraldine Base/Bentonite Composites

Abstract: Copolymers of o-nitroaniline and o-phenylenediamine/Hydrophilic bentonite composites were synthesized by 1:1 molar ratios of the respective monomers with different percentages of nanoclay via modified in situ chemical co-polymerization. The results were justified by measuring the FT-IR for the pristine copolymer and copolymer bentonite composites. The thermal stability was studied by TGA thermograms indicating that the copolymer emeraldine base/bentonite composites were thermally more stable than the pristine copolymer. Also, both a hypsochromic and a blue shift were observed and recorded by UV–Vis absorption spectra. The X-ray powder diffraction patterns were utilized to examine the nature of the copolymer emeraldine base and the bentonite composites. The antibacterial efficacy of the copolymer emeraldine base/bentonite composites was investigated towards both Gram-positive and Gram-negative bacteria.

Synthesis and Characterization of Nanostructured Magnesium Oxide: Insight from Solid-State Density Functional Theory Calculations

Abstract: Nano-sized MgO was synthesized by sol–gel method using magnesium acetate tetra hydrate [Mg(C2H3O2)2·4H2O] as a precursor and characterized using various techniques including X-ray diffraction (XRD), atomic force microscopy (AFM), Fourier transform infrared and ultraviolet–visible absorption. Using the XRD pattern, average crystallite size and lattice parameters of MgO nanoparticles were calculated. The average crystallite size of MgO was found to be 17.4 nm. The crystallite size of MgO from WH-plot analysis was calculated 18.09 nm. AFM shows the acicular (needle like) morphology having average particle size 23 nm. The band gap of MgO was calculated as 4.520 eV with the help of Tauc plot. The optical properties including the dielectric, absorption, reflectivity and energy-loss spectra was calculated by the density functional theory and analyzed on the basis of electronic structures. The electronic band structure and density of states indicates that MgO has a direct energy band gap of 4.514 eV which is comparable with the experimental band gap of MgO.

A Facile Novel Sonochemical-Assistance Synthesis of NiSe2 Quantum Dots to Improve the Efficiency of Dye-Sensitized Solar Cells

Abstract: In this work, NiSe2 quantum dot (QD) has been successfully synthesized from the reaction of SeCl4 with pomegranate marc peels (PMP) dyes-Ni as a novel nickel precursor in the presence of potassium borohydride (KBH4) through a simple and novel sonochemical-assistance route. In this work for preparing of nickel precursor and dye solar cells, the PMP was used because the PMP has several dyes such as proanthocyanidins and flavonoids that can easily be extracted by using ions. Besides, a possible reaction mechanism of the NiSe2-QDs has been discussed. Furthermore, for investigation the effect of different dyes and QDs on the solar cell yield, several experiments have been performed.

Thermo-responsive Ruthenium Dendrimer-based Catalysts for Hydrogenation of the Aromatic Compounds and Phenols

Abstract: In this work thermo-responsive ruthenium catalysts, based on the poly(propylene imine) dendrimers cross-linked with the poly(ethylene glycol) diglycidyl ether, have been prepared for the first time. The materials obtained were characterized by X-ray photoelectron spectroscopy and transmission electron microscopy, and tested in the phenol and benzene hydrogenation. Conditions for the metal impregnation into the polymeric matrix were demonstrated to have a great influence both on physical chemical properties of the synthesized catalysts (metal loading, mean particles size, surface structure etc.), and, as a consequence, on their hydrogenation activity and thermo-responsive properties.

Synthesis, Ceramic Conversion and Microstructure Analysis of Zirconium Modified Polycarbosilane

Abstract: Polymer derived ceramics have been widely being explored as high temperature structural components in aerospace as rocket nozzles, nose tip and leading edges of reusable launch vehicles. Polycarbosilane (PCS) was modified by a condensation reaction with zirconium acetylacetonate [Zr(acac)4] to form polyzirconocarbosilane (PZrCS). A series of PZrCS were synthesized, which could be transformed into Si–Zr–C ceramic phases on pyrolysis. The ceramic yield of PCS was significantly improved by the introduction of zirconium into the system. The XRD patterns of the PZrCs show the characteristic peaks of −SiC at 1300 °C and at 1500 °C the characteristic peaks of ZrC and ZrO2 were observed. The carbothermal reaction in PZrCS was completed at 1650 °C and the resulting ceramic was non-oxide SiC/ZrC phase. The SEM images proved that the increase in concentration of zirconium in the final ceramic decreases the surface uniformity. HRTEM analysis of PZrCS heat treated at 1650 °C shows the evolution of oxide free ZrC/SiC phase with compatible grain boundaries without stacking fault. It could be concluded that the technique of introducing ultra-high temperature ceramic phases into the SiC matrix is an effective approach to improve the high-temperature performance of silicon based ceramics.

Syntheses, Structures and Catalytic Properties of Cobalt(II) and Silver(I) Coordination Polymers Based on Flexible Bis(2-methyl benzimidazole) and Dicarboxylic Acids

Abstract: Two coordination polymers formulated as [Co2(2,6-ndc)2(L)]n (1) and [Ag(L)(1,4-Hndc)]n (2) (L = 1,1′-(1,4-butanediyl)bis(2-methylbenzimidazole), 2,6-H2ndc = 2,6-naphthalenedicarboxylic acid, 1,4-H2ndc = 1,4-naphthalenedicarboxylic acid) were synthesized under hydrothermal conditions and characterized by IR, elemental analysis, and single-crystal X-ray diffraction. The structural analysis reveals that complex 1 exhibits an unprecedented 3D framework with threefold interpenetrating xah topology. Complex 2 shows a 1D “Ω”-like chains bridged by L ligands, which is further extended via O–H···O hydrogen bonding interactions into a 2D (4,4) supramolecular layer. The thermal stability and catalytic properties of two complexes for the degradation of Congo red dye in a Fenton-like process was also investigated.

Synthesis, Characterization, and Application of Hybrid Inorganic–Organic Composites (K/Na)ZrSi(R)Ox

Abstract: Hybrid inorganic–organic composites, (K/Na)ZrSi(R)Ox, were synthesized from the hydrolysis of the mixture of zirconium n-propoxide (Zr(OPrn)4) and 3-glycidyloxypropyltrimethoxy silane (GPTS) in 1:1 mol ratio. The hydrolysis reaction was carried out with 0.1 molar HCl in 150 ml of butanol. Then, the synthesized Zr(OPrn)4-GPTS-hydrolyzate reacted with KOBut and NaOSiMe3 in 1:1 mol ratio at 40 and 50 °C for 24 h, respectively. After these stages, composites were washed and dried under vacuum. Composites and their oxide prepared at 1250 °C by calcinations were characterized by a combination of powder X-ray diffraction, scanning electron microscope, energy dispersive X-ray, Brunauer–Emmett–Teller analysis, Barrett–Joyner–Halenda analysis, and Fourier transform infrared spectroscopies. These hybrid inorganic–organic composites except oxides were used as catalysts in order to see their activities in the polymerization of e-caprolactone (e-CL). This study showed that new composite materials except their oxides were effective catalyst in e-CL polymerization.