One‐pot synthesis of binderless zeolite A spheres via in situ hydrothermal conversion of silica gel precursors

One‐pot synthesis route was explored for preparing binderless zeolite A via an in situ hydrothermal transformation process involving the preformation of silica gel precursors. Synthesis process was optimized and resulting samples were characterized using XRD, Raman spectroscopy, EDS, ²⁹Si and ²⁷Al NMR spectroscopy, SEM, HRTEM, and pore structure analyses. Furthermore, the kinetics for the in situ synthesis was investigated and the underlying crystallization mechanism was interpreted. The transformation of silica precursors was accomplished via controlling the synthesis parameters which govern the crystallization through determining the dissolution rate of silica nanoparticles, diffusion of Al species into silica precursors and crystal nuclei growth. Subsequently, Al species could contact and react with released Si species from silica nanoparticles to build the structural units that finally construct the LTA framework through self‐organized arrangement. On pure zeolite A phase basis, the synthesized binderless sample exhibits higher specific surface area and n‐paraffins adsorption capacity than binder‐containing zeolite. © 2018 American Institute of Chemical Engineers AIChE J, 64: 4027–4038, 2018     

One‐pot synthesis of monodispersed phosphazene‐containing microspheres with active amino groups

An amine‐terminated nucleophile Hexakis (4‐aminophenoxy) cyclotriphosphazene (HACP) was synthesized. Its chemical structure was identified by ¹H NMR and ³¹P NMR. Novel monodispersed phosphazene‐containing microspheres with active amino groups on the surface have been successfully prepared through a one‐pot precipitation polymerization of hexachlorocyclotriphosphazene with HACP. Just by single step, the microspheres were synthesized without stirring, surfactant and ultrasonic irradiation. The diameter of the obtained microspheres ranged from 0.1 to 0.5 μm with the rough surface. And, the onset of the thermal‐degradation temperature was 460°C, which is attributed to the highly cross‐linked structure and the introduced of the cyclotriphosphazene rings. Moreover, the products at variable stages of polymerization were measured by TEM. The formation mechanism was proposed which is corresponding with an oligomeric species absorbing mechanism. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43336.     

Synthesis of hexagonal phases of WN and W2.25N3 by high‐pressure metathesis reaction

Hexagonal tungsten nitrides were synthesized by the metathesis reaction between WCl₆ and NaN₃ under high pressure and temperature. As well as tungsten mononitride (WN), which is isostructural with hexagonal tungsten carbide (WC), a nitrogen‐rich hexagonal compound was also confirmed in the product. The ratio of nitrogen to tungsten was determined to be 1.34 by the quantitative combustion method. The composition was estimated to be W_2.25N₃ by considering the crystal structure that is best explained by the X‐ray diffraction profile. Volume compression measurements under hydrostatic pressure revealed that the WC‐type WN has a higher bulk modulus (K₀ = 342 ± 1 GPa) than that of hexagonal W_2.25N₃ (K₀ = 291 ± 2 GPa).     

Polymer‐based catalysts for toluene hydrogenation

Crosslinked poly(4‐vinylpyridine‐co‐styrene) was synthesized by radical polymerization. Catalysts having 1 wt % Pd were obtained by impregnation of a copolymer, poly(4‐vinylpyridine‐co‐styrene) with a Pd colloidal dispersion. We modified metal particle sizes by changing the aging period of the colloidal dispersion, with the average size in the range of 2.5–4.3 nm. The most probable structure of the metal cluster attached to the polymers is described. X‐ray diffraction, transmission electron microscopy (TEM), and H₂? O₂ titrations were used as characterization techniques. The H₂ consumption during titration was extremely low, and the calculated metal dispersion was between 15 and 25 times lower than those estimated from TEM. This suggests that the Pd crystals were almost completely covered by the polymer. The vapor‐phase hydrogenation of toluene on resins supported Pd catalysts were studied. The catalysts in the hydrogenation of toluene exhibited low activity, and the obtention of significant selectivities to partial hydrogenation products (close to 60 mol %) was remarkable. The results are explained in terms of a significant decrease in the hydrogenation capacity due to the coverage of metal particles by the resin. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 381–385, 2002     

One‐pot synthesis of cobalt‐incorporated polyglycerol ester as an antimicrobial agent for polyurethane coatings

Cobalt‐incorporated poly(glycerol ester) (Co–PGE) was synthesized by the polycondensation of glycerol and adipic acid followed by the reaction with cobalt(II) hydroxide under solvent‐free and noncatalyzed one‐pot synthesis conditions. The reaction was monitored through the acid value and hydroxyl value determination. The chemical structure and molecular weight of the poly(glycerol ester) (PGE) and Co–PGE were characterized by Fourier transform infrared spectroscopy, ¹³C‐NMR, gel permeation chromatography, and inductively coupled plasma mass spectrometry. Co–PGE with a 59.3% degree of branching was incorporated with up to 5.0% w/w cobalt, and it exhibited antimicrobial inhibition against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans in a broth microdilution study. Polyurethane (PU) coatings were prepared by the blending of 0.5–35% w/w Co‐PGE containing with 5% w/w of cobalt with blank PGE, poly(ethylene glycol) with a molecular weight of 6000, poly(caprolactone diol) with a molecular weight of 2000, and additives to react with isophorone diisocyanate. The prepared PUs demonstrated mild to high antimicrobial activities against E. coli, S. aureus, Bacillus subtilis, and C. albicans strains in a disc diffusion test. PU prepared with 0.5% w/w Co–PGE showed a mild inhibition activity against S. aureus, and PU prepared with 10% w/w Co–PGE demonstrated a high inhibition activity against C. albicans. This study demonstrated that value‐added Co–PGE synthesized from glycerol has the potential as an antimicrobial agent for polymer coatings in biomedical devices. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46045.     

Microwave assisted synthesis and characterization of single‐phase tabular hexagonal newberyite,an important bioceramic

Magnesium phosphate compounds such as newberyite (MgHPO₄·3H₂O) and struvite (MgNH₄PO₄·6H₂O) are becoming important alternatives to calcium phosphates in hard tissue replacements. So far, newberyite has received lesser attention with respect to struvite. Therefore, the broad aim of this paper is to report an easy synthesis technique and characterization of single‐phase newberyite, which may have diverse uses as a bioceramic material. Specifically, we describe a simple and robust microwave‐assisted process for the synthesis of single‐phase newberyite in tabular hexagonal form. Second, we soak the newberyite powders in simulated body fluid, a solution which mimics the pH and ion concentration of human blood plasma, for 7 days and analyze the apatite formation on the crystals. Third, we report that single‐phase newberyite, by itself, does not possess antibacterial property.     

Additive manufacturing of periodic ceramic substrates for automotive catalyst supports

Additive manufacturing (AM) has the potential to revolutionize engineering because of its advantages in the product development phase. The revolution consists in the new approach of components’ design by function and no longer by manufacturability. This is the motivation driving authors to design and realize by additive manufacturing a new catalyst support for automotive exhausts which is no longer constrained by the industrial manufacturing methods and thus allows an optimized flow of the exhaust gasses. This work presents a new class of periodic cellular ceramic substrates. To authors’ knowledge this is the first time such kind of structures are employed in the automotive field. After a review the different ceramic AM techniques which are currently utilized in the production of highly complex ceramic architectures, the most suited one was selected and several samples were produced by AM. They were finally characterized via microscopic analysis (SEM, CT) compression tests revealing the best printing configuration for their mechanical behavior.     

Polyaniline salts as polymer‐based solid acid catalyst for low molecular weight poly(lactic acid)

Polymer‐based solid acid catalyst, polyaniline (PANI) salt, is used for the first time to synthesize polymer. In continuation of our work to synthesize organic chemicals using PANI‐based solid acid catalyst, in this work, polylactic acid is synthesized by the condensation polymerization of lactic acid using PANI salts. PANI salts are characterized by FTIR, FE‐SEM, and TGA analyses. Polymerization of lactic acid in xylene solvent at 140°C for 24 h with the use of very low amount of PANI catalysts gave polylactic acid (PLLA) in the order: PANI‐MSA (46%) > PANI‐TFA (33%) > PANI‐Bi(OTf)₃ (27%) > PANI‐Cu(OTf)₂ (20%) > PANI‐Yb(OTf)₃ (15%). Molecular weights of PLLA synthesized using PANI‐MSA and PANI‐TFA are found to be 4385 and 4830, respectively. This methodology gives highly crystalline polymer with mushroom cap‐like morphology. Advantage of this methodology is the use of easily synthesizable, recyclable, easily handlable, cheaper, and eco‐friendly nature of the catalyst. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41147.     

Nucleation Energy Barriers for Volume-Conserving Shape Changes of Crystals with Nonequilibrium Morphologies

This paper quantifies the nucleation energy barrier that must be overcome if a faceted, defect-free particle with a nonequilibrium morphology is to change shape by intraparticle transport. Two types of crystals are considered: those whose equilibrium form is a truncated sphere and those whose equilibrium form is a cube. Numerical estimates show that, for a particle near equilibrium, the barrier becomes insurmountable for a facet larger than a few tens of nanometers. For nonequilibrium shapes where material must be transferred from faceted surfaces to uniformly curved surfaces to reach the equilibrium shape, the facets enlarge without a nucleation barrier (at a rate limited by diffusion or surface attachment kinetics) until they reach a fraction of their equilibrium size that is typically between 0.5 and 0.75. At this point, a significant barrier is encountered that, in the absence of step producing defects, prevents the particle from continuing toward equilibrium. For nonequilibrium shapes where material must be transferred to faceted surfaces from other parts of the crystal for it to reach the equilibrium shape, significant energy barriers for the nucleation of new layers persist even when the shape is far from equilibrium. Predictions from our model are compared to experimental observations reported by other researchers.     

New manganese catalyzed regiocontrolled synthesis of poly(2,5‐dialkyl‐1,4‐phenylene oxide)s

A new catalyst system is developed for regiocontrolled synthesis of poly(2,5‐dialkyl‐1,4‐phenylene oxide)s by oxidative coupling polymerization of 2,5‐dialkylphenol. The treatment of the α‐benzoin oxime with manganese chloride in methanol under basic condition led to the formation of manganese benziloxime complex in which α‐benzoin oxime was converted to benziloxime and coordinated to manganese as bidentate ligands. The polymerizations were conducted in toluene using manganese benziloxime complex and dibutylamine in a continuous flow of oxygen, and the structures, properties of the catalyst, and polymers were studied by nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and gel permeation chromatography (GPC). The catalyst showed high regioselectivity and reasonably good yields to afford the poly(2,5‐dimethyl‐1,4‐phenylene oxide)s with 1,4‐C‐O linkage structure which possessed melting point higher than the poly(p‐phenylene sulfide) or type II liquid crystalline polymer. The regioselectivity was enhanced when employing molecular sieves‐supported manganese catalyst system at 90°C and the crystallinity of poly(2,5‐dimethyl‐1,4‐phenylene oxide)s was estimated by wide‐angle X‐ray scattering (WAXS) and DSC. The crystallinity was calculated about 23.7% and a heat‐reversible melting and crystallization behavior occurred at 327.8 and 306.8°C, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Rapid synthesis of nanocrystalline YAG via microwave‐assisted solvothermal process

A rapid synthesis procedure for the preparation of nanocrystalline yttrium aluminium garnet (nYAG) particles has been developed, for the first time, using the combination of subcritical conditions and microwave irradiation. It is believed that the use of butanediol delayed the onset of pressure rise due to its low partial pressure, while the microwaves facilitated a selective crystallization of nanocrystalline YAG particles in the solvent medium. This methodology was found to encourage rapid bulk nucleation with minimal particle growth or agglomeration of nYAG particles. The resultant powder characteristics, examined using XRD and TEM analyses, revealed that a narrow window of pressure and temperature conditions needed to be maintained to achieve spherical particles in the size range 60‐80 nm without any intermediate phases being formed. The STEM/EDX and FTIR results obtained suggested that the nucleated YAG particles were masked by carbon clouds until they were completely crystallized into single phase YAG particles; this allowed them to be dispersed in water with little agglomeration.     

Hybrid organic-inorganic Cu(II) iminoisonicotine@TiO2@Fe3O4 heterostructure as efficient catalyst for cross-couplings

Two novel mononuclear copper (II) complex catalysts were synthesized from a new tridentate iminoisonicotine ligand (HL) by coordination with Cu(II) ion, with (CuL@TiO₂@Fe₃O₄) and without (CuL) immobilization on TiO₂-coated nanoparticles of Fe₃O₄. The ester moiety on the back of the ligand was utilized for immobilization on nanoparticles of Fe₃O₄. Both ligand and CuL complex were fully characterized by using alternative spectral techniques (nuclear magnetic resonance, infrared, ultraviolet-visible and mass spectroscopy, and elemental analyses). Different analytical techniques were used to identify the structural feature and morphology of the immobilized copper catalyst (CuL@TiO₂@Fe₃O₄) shell-shell-core system. The structural analysis revealed that the catalyst system is composed of both agglomerated nanospheres and deformed nanorods. Both copper catalysts, immobilized CuL@TiO₂@Fe₃O₄ and un-immobilized CuL were studied in heterogeneous and homogeneous catalysis, respectively, for Suzuki-Miyaura (C–C) and Buchwald-Hartwig (C–N) cross-coupling reactions of various heteroaryl halides. Both catalysts showed good catalytic potential under the controlled optimal reaction conditions. In contrast to the homogeneous catalyst (CuL), the heterogeneous catalyst (CuL@TiO₂@Fe₃O₄) showed slightly better catalytic performance. The characteristic obtains supported the catalytic potential of the current samples. Reusability/recycling of both catalysts was also investigated in C–C cross-coupling reactions. It was found that the homogeneous catalyst (CuL) could be only recycled up to three times, whereas the heterogeneous one (CuL@TiO₂@Fe₃O₄) could be reused up to seven times with good efficiency.     

Microstructural investigation of butt‐fusion joint in high‐density polyethylene pipes using wide‐ and small‐angle X‐ray scattering

The melt fusion zone (MFZ) of polyethylene pipe was investigated employing synchrotron wide‐ and small‐angle X‐ray scattering at various locations in MFZ by changing X‐ray incidence angles to probe three‐dimensional structural features. It was determined that the crystals were oriented in two different modes. One is that the polymer chains are oriented parallel to the joint interface line consistently throughout the MFZ. The other is that the crystals are oriented in particular directions depending on the positions in MFZ. The combination of pressure and melt flow during joining process resulted in such a complex structure. It was notable that the boundary of MFZ against the base material was found to be very different depending on the structures involved such as crystallographic unit orientation, lamellae orientation, crystallinity, and spherulitic morphology. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45668.     

Decorated‐magnetic‐nanoparticle‐supported bromine as a recyclable catalyst for the oxidation of sulfides

Herein, we present a strategy for supporting bromine as a catalyst for the oxidation of sulfides. In this strategy, branched poly(ethylene imine) was first decorated by magnetic oxide and then used to support liquid bromine to obtain solid polymeric bromine (M@PEI@Br) nanoparticles. Compared with free bromine, the stability of the M@PEI@Br nanoparticles improved obviously. The oxidation of thioanisole to methyl phenyl sulfoxide was chosen as a reaction model to evaluate the catalytic activity of the M@PEI@Br nanoparticles. All of the obtained results verify that the M@PEI@Br nanoparticles exhibited excellent catalytic efficiency and could accelerate the oxidation process under solvent‐free conditions at room temperature; this highlighted the potential of decorated polymers to support active and unstable small‐molecule organic catalysts. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46036.     

Self‐limited crystallization‐mediated removal of hydroxyl in glass

The effective removal of hydroxyl groups (OH) is receiving the attention of scientists interested in developing high‐performance photonic glass. Previous approaches rely on stringent control of the various drying techniques which meet with limited success in silicate glass obtained by the sol‐gel method. Here, we present a novel in situ strategy to remove structural OH groups, based on the self‐limited nanocrystallization‐triggered local chemical reaction between OH and F^? in the glassy phase. The experimental data revealed that a more than 100‐fold increase in the emission intensity can be realized. Moreover, the mechanism was discussed and it can be attributed to the effective removal of structural OH with especially strong binding energy. The results suggest an innovative avenue for the development of photonic glasses with efficient luminescence, excellent optical transmission, and improved reliability.     

One‐pot synthesis of silver‐modified sulfur‐tolerant anode for SOFCs with an expanded operation temperature window

To develop solid oxide fuel cells (SOFCs) capable of operating on sulfur‐containing practical fuels at intermediate temperatures, further improvement of the sulfur tolerance of a Ni + BaZr_0.4Ce_0.4Y_0.2O_3‐δ (BZCY) anode is attempted through the addition of some metal modifiers (Fe, Co, and Ag) by a one‐pot synthesis approach. The effects of these modifiers on the electrical conductivity, morphology, sulfur tolerance, and electrochemical activity of the anode are systematically studied. As a result, the cell with Ag‐modified Ni + BZCY anode demonstrates highest power output when operated on 1000 ppm H₂S‐H₂ fuel. Furthermore, the Ag‐modified anode displays much better stability than Ni + BZCY with 1000 ppm H₂S‐H₂ fuel at 600°C. These results suggest that the addition of Ag modifier into Ni + BZCY is a promising and efficient method for improving the sulfur tolerance of SOFCs. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4287–4295, 2017     

MgO/NaX zeolite as basic catalyst for oxidative methylation of toluene with methane

Oxidative methylation of toluene with methane was studied over a series of MgO/NaX zeolite catalysts. The effect of MgO on the zeolite was examined by X-ray diffraction (XRD) and temperature-programmed desorption (TPD) of CO₂. The results indicated that the conversion, selectivity and yield of C₈ hydrocarbons (ethylbenzene and styrene) are significantly improved by impregnation of maximum 13 wt.% MgO into the zeolite. The latter catalyst also displays a good stability. It is found that the amount of active sites but not their strength depends on the content of MgO in the zeolite. The catalysts possess well preserved crystal structure and low amount of MgO crystal phase.