Facile synthesis of ethylene–propylene fully alternating copolymer and comparison with random copolymer of similar composition

A precisely sequenced ethylene–propylene (EP) fully alternating copolymer was synthesized via trans‐1,4‐polymerization of isoprene catalyzed by Ziegler–Natta catalyst followed by hydrogenation. This EP copolymer was used as model polymer for studying structure–property relationship. An ethylene–propylene random copolymer (ethylene–propylene rubber [EPR]) with similar ethylene content was also prepared for comparison, and the effect of comonomer sequence distribution on properties was investigated. The copolymer chain structures were monitored by ¹H and ¹³C NMR and Fourier translation infrared. Differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis, and tensile tests were employed to determine the thermal and mechanical properties. The fully alternating copolymer EP gives a more precise glass transition comparing than EPR. Further understanding on thermal properties and aggregation behavior of ethylene–propylene copolymers is made possible by this comparative study. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45816.     

氧化甲壳素的合成

在TEMPO（2，2，6，6-四甲基哌啶氮氧自由基）和NaBr的催化作用下用NaClO溶液氧化甲壳素得到氧化甲壳素；产品纯化后，经^13C-NMR和红外分析鉴定出糖基C6位羧基的存在；同时对原料的选择和反应的工艺备件作了初步的探索，得到了合适的反应温度（0-5℃）和pH值（10-11），产率迭到45％左右。     

Facile synthesis of sulfo-functionalized mesoporous silica with strong acidity by temperature-controlled calcination

The facile synthesis of sulfo-functionalized mesoporous silica (MCM-41) by a one-step process of surfactant removal and thiol oxidation technique through a temperature-controlled calcination of a precursor is presented. Thiol containing mesoporous silica is synthesized as a precursor by hydrolysis and co-condensation of tetramethoxysilane (TMOS) and mercaptopropyl trimethoxysilane (MPTMS). The samples thus prepared are shown to preserve the ordered two-dimensional hexagonal structure and pore characteristics of MCM-41, while functionalizing the material with sulfo groups which was oxidized from thiol groups providing strong acidity. The acidity of the material is demonstrated by high ammonia uptakes and low differential adsorption energy of ammonia.     

N-取代苄胺的简便合成法

苯并三氮唑、胺与苯甲醛发生 Mannich 反应生成 N-取代-1-苯并三氮唑苄胺3。3在 NaBH_4 作用下还原生成N-取代苄胺4。反应条件温和、副反应少、产率高,苯并三氮唑可回收利用。     

Facile synthesis of CdS nanoparticles photocatalyst with high performance

A simple one-step solid-state reaction has been introduced to synthesize CdS nanoparticles. The as-prepared CdS product was characterized by X-ray powder diffraction (XRD), BET surface area measurement, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), particle size distribution (PSD) and UV–vis absorption spectrum. The experiment results reveal that the CdS product was composed of nanoparticles about 60 nm in diameter, of which specific surface area is 78.02 m²/g. The photocatalysis results indicate that the CdS nanoparticles exhibit excellent photocatalytic activity for the degradation of rhodamine B under UV irradiation. Nearly 95% of rhodamine B was degraded after 60 min of irradiation, higher than that of P25, which is due to the large specific surface area and mesoporous structure.     

Facile synthesis of a novel photocatalyst with integrated features for industrial effluents treatment

Faster charge transport, excellent charge separation, narrow bandgap energy, lower electron-hole pair recombination rate, and high visible light absorption are the key features of an ideal photocatalyst material. Undoubtedly, semiconductor-based photocatalysts having remarkable charge separation efficiency have attracted considerable attention for degrading hazardous organic pollutants from contaminated water. So herein, a novel composite of reduced graphene oxide (rGO) supported by gadolinium doped bismuth yttrium oxide (Gd-BiYO₃/rGO) was prepared by simple precipitation and ultrasonication method. The photocatalytic efficiency of the Gd-BiYO₃/rGO composite was examined comparatively with pure BiYO₃ and Gd-BiYO₃ samples to degrade Methylene Blue (MB) dye under visible light irradiation. The Gd doping and rGO incorporation into BiYO₃ increased the conductivity, improved the charge transfer efficiency, and impeded the charge recombination, resulting in superior photocatalytic activity of Gd-BiYO₃/rGO. The kinetic studies exhibited the 96.2%, 61.5%, and 48.3% degradation of MB after 80 min irradiation of 1 SUN visible light under Gd-BiYO₃/rGO, Gd-BiYO₃, and BiYO₃, respectively. The Gd-BiYO₃/rGO composite degraded the MB dye at a rate (k = 0.0328 min^-1) that is 5.05 and 2.68-fold higher than pure BiYO₃ and Gd-BiYO₃, correspondingly. The transient photocurrent response of Gd-BiYO₃/rGO was comparatively 4.7 and 2.8 times greater than that of BiYO₃ and Gd-BiYO₃ photocatalysts, respectively. The dominant photocatalytic performance of Gd-BiYO₃/rGO is primarily ascribed to the formation of heterojunctions between rGO nanosheets and Gd-BiYO_3, which facilitate higher visible light absorbance, effective charge separation, and transfer through interfacial layers, more dye adsorption, lower charge transfer resistance, and hamper electron-hole pair recombination. Overall, the electrochemical results suggest that the current study provides an effective way to synthesize a heterostructure photocatalyst for removing organic pollutants from industrial effluents.     

Facile synthesis of well-defined CeO2 hollow spheres with a tunable pore structure

Herein, SiO₂@CeO₂ composite microspheres were successfully prepared via a hydrothermal assisted layer-by-layer self-assembly method employing colloid SiO₂ as the template, which was fabricated by a typical Stöber method. Monodispersed CeO₂ hollow spheres with a narrow size distribution were achieved after etching colloid SiO₂ templates through NaOH. The resultant samples were characterized by X-ray diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscopy (TEM), Fourier translation infrared spectroscopy (FT-IR), X-ray photoelectron spectrum (XPS), and Nitrogen adsorption–desorption isothermal. Specifically, the shell thickness and the mesoporous structure of the hollow sphere can be easily controlled by changing the concentration of cerium source.     

Facile synthesis of functional copolymers with pendant vinyl groups by using asymmetrical divinyl monomers

Polymers bearing pendant vinyl groups have attracted significant attraction because they can be further modified for required applications, but their syntheses are still a big challenge. Herein, allyl methacrylate was catalyzed using a phosphazene base to homopolymerize or copolymerize with 2‐(N, N‐dimethylamino) ethyl methacrylate, affording vinyl functional polymers, which were further successfully tailored by the thiol–ene coupling reaction. The result showed that both the homopolymerizations and copolymerizations could proceed at room temperature with very high monomer conversions. The contents of pendant double bonds in the copolymers were approximately equal to the monomer feeds, but the LCST of the statistical copolymers linearly decreased with increasing AMA content. This strategy offered a new scalable and facile strategy for vinyl functional polymers, would have a wide practical application in many fields. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42758.     

Facile synthesis of mesoporous titanium dioxide nanocomposites with controllable phase compositions by microwave-assisted esterification

Mesoporous titanium dioxide nanocomposites with controllable phase compositions and high surface areas were synthesized through convenient, fast, and one-step microwave-assisted esterification method. The introduction of microwave in the synthetic reactions not only accelerates the esterification reaction but also promotes the fast crystallization. By changing reaction temperature, microwave irradiation time, the amount of staring materials and the composition of solvents, pure anatase, pure rutile or mixed phase titanium dioxide nanocomposites were obtained in minutes. Meanwhile, the size of crystallite can be controlled by the reaction temperature. The as-synthesized materials display significative photocatalytic activities without any further disposal, among which the material with 3.6% rutile shows the best effect in degradation of methylene blue under UV-light irradiation. Moreover, the nitrogen adsorption–desorption results illustrate the obtained samples are mesophases. It is also interesting that the pure rutile has specific surface area as high as 210 m² g^?1 calculated by BET equation. The method can control the hydrolysis of TiCl₄ well and dramatically shorten the preparation time of titanium dioxide.     

Novel synthesis of highly branched comb-like polymers by coupling reaction of polystyryllithium with 1,1-diphenylethenyl-functionalized polystyrene

Well-defined highly branched comb-like polystyrenes (PS) having one branch in each repeating unit have been successfully synthesized by the coupling reaction of living PS anions with 1,1-diphenylethenyl (DPE) groups along PS backbone prepared via atom transfer radical polymerization. When excess polystyryllithium (PSLi) was used, the quantitative grafting efficiency was achieved. The resulting polymers were characterized by NMR, IR, GPC, and SLS in detail.     

Chemical synthesis of a dual branched malto-decaose: a potential substrate for alpha-amylases

A convergent block strategy for general use in efficient synthesis of complex alpha-(1-->4)- and alpha-(1-->6)-malto-oligosaccharides is demonstrated with the first chemical synthesis of a malto-oligosaccharide, the decasaccharide 6,6'-bis(alpha-maltosyl)-maltohexaose, with two branch points. Using this chemically defined branched oligosaccharide as a substrate, the cleavage pattern of seven different alpha-amylases were investigated. Alpha-amylases from human saliva, porcine pancreas, barley alpha-amylase 2 and recombinant barley alpha-amylase 1 all hydrolysed the decasaccharide selectively. This resulted in a branched hexasaccharide and a branched tetrasaccharide. Alpha-amylases from Asperagillus oryzae, Bacillus licheniformis and Bacillus sp. cleaved the decasaccharide at two distinct sites, either producing two branched pentasaccharides, or a branched hexasaccharide and a branched tetrasaccharide. In addition, the enzymes were tested on the single-branched octasaccharide 6-alpha-maltosyl-maltohexaose, which was prepared from 6,6'-bis(alpha-maltosyl)-maltohexaose by treatment with malt limit dextrinase. A similar cleavage pattern to that found for the corresponding linear malto-oligosaccharide substrate was observed.     

2-甲酰胺环己酮的简便合成

以二甲苯作溶剂,环己酮、碳酸铵和尿素为原料,在无催化条件下,经两步反应制得2-甲酰胺环己酮。研究了聚合反应温度、碳酸铵和二甲苯的用量对产品质量和收率的影响。结果表明,最佳质量比为50∶18∶9∶25的环己酮、尿素、碳酸铵和二甲苯的混合物在137~142℃经聚合反应生成螺环,螺环用9.6%的稀硫酸水解即得产品,总收率54.6%。     

Facile synthesis of nanocrystalline magnesium oxide with high surface area

Nanocrystalline magnesium oxide with high surface area has been synthesized by precipitation method using ammonium hydroxide and polyvinyl alcohol as precipitant and polymeric surfactant, respectively. The results show that the polymeric surfactant (PVA) has a significant effect on the synthesis of MgO nanocrystals. The specific surface area of the MgO powder decreases from 123 m²g^− 1 to 61 m²g^− 1and the crystallite size on the (200) plane increases from 12.2 nm to 14.2 nm with increasing temperature from 600 °C to 800 °C. Transmission electron microscopy (TEM) and N₂ adsorption/desorption isotherm also show a nanostructure consisting of aggregates or agglomerates of particles forming slit shaped pores (plates or edged particles like cubes).     

Facile synthesis of hexagonal boron nitride fibers with uniform morphology

Hexagonal boron nitride (h-BN) fibers were synthesized via the polymeric precursor method using boric acid (H₃BO₃) and melamine (C₃H₆N₆) as raw materials. The precursor fibers were synthesized by a water bath and BN fibers were prepared from the precursor at 1600 °C for 3 h in flowing nitrogen atmosphere. The products were characterized by X-ray powder diffraction, Fourier transformation infrared spectroscopy, thermogravimetry and scanning electron microscopy. The results showed that h-BN fibers with uniform morphology were successfully fabricated. The well-synthesized fibers were 1–2 μm in diameter and 200–500 μm in length.     

Facile synthesis of ultrathin magnetic iron oxide nanoplates by Schikorr reaction

In this work, a very facile one-pot hydrothermal synthesis approach has been developed for the preparation of ultrathin magnetite nanoplates. The hydrothermal procedure was performed by aging ferrous hydroxide under anaerobic conditions, which is known as Schikorr reaction. Ethylene glycol (EG), which was introduced to the reaction as another solvent, played a critical role in the formation process of these nanoplates. Typically, hexagonal Fe₃O₄ nanoplates with a thickness of 10 to 15 nm and a side length of 150 to 200 nm have been synthesized with EG/H₂O = 1:1 in experiments. Our data suggest that the thickness of Fe₃O₄ nanoplates decreases, and the shape of the nanoplate becomes more irregular when the concentration of EG increases. The as-prepared Fe₃O₄ nanoplates were highly crystallized single crystals and exhibited large coercivity and specific absorption rate coefficient.     

Controllable synthesis of branched ZnO/Si nanowire arrays with hierarchical structure

A rational approach for creating branched ZnO/Si nanowire arrays with hierarchical structure was developed based on a combination of three simple and cost-effective synthesis pathways. The crucial procedure included growth of crystalline Si nanowire arrays as backbones by chemical etching of Si substrates, deposition of ZnO thin film as a seed layer by magnetron sputtering, and fabrication of ZnO nanowire arrays as branches by hydrothermal growth. The successful synthesis of ZnO/Si heterogeneous nanostructures was confirmed by morphologic, structural, and optical characterizations. The roles of key experimental parameters, such as the etchant solution, the substrate direction, and the seed layer on the hierarchical nanostructure formation, were systematically investigated. It was demonstrated that an etchant solution with an appropriate redox potential of the oxidant was crucial for a moderate etching speed to achieve a well-aligned Si nanowire array with solid and round surface. Meanwhile, the presence of gravity gradient was a key issue for the growth of branched ZnO nanowire arrays. The substrate should be placed vertically or facedown in contrast to the solution surface during the hydrothermal growth. Otherwise, only the condensation of the ZnO nanoparticles took place in a form of film on the substrate surface. The seed layer played another important role in the growth of ZnO nanowire arrays, as it provided nucleation sites and determined the growing direction and density of the nanowire arrays for reducing the thermodynamic barrier. The results of this study might provide insight on the synthesis of hierarchical three-dimensional nanostructure materials and offer an approach for the development of complex devices and advanced applications.     

A novel method for synthesis of polypyrrole grafted chitin

In this paper we report the grafting of polypyrrole (PPy) on to a biopolymer, chitin. Polypyrrole is chemically grafted onto chitin by using ammonium peroxydisulphate (APS) initiator, in the presence of 1 M HCl. The effects of concentration of polypyrrole on graft copolymer are studied by determining the grafting percentage. Grafting of polymer is further verified by dissolution studies. Grafted polymer samples are characterized by Fourier transform infrared spectroscopy (FTIR), UV-Vis absorption spectrum, X-ray diffraction (XRD), Differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA) and conductivity studies. Mechanism of grafting has been proposed on the basis of experimental results.     

Facile synthesis and promising antibacterial properties of a new guaiacol-based polymer

A new acrylamide-type monomer (N-(4-hydroxy-3-methoxy-benzyl)-acrylamide) derived from guaiacol was successfully synthesized. Polymers containing guaiacol moiety were obtained via conventional radical polymerization of this monomer with AIBN as initiator. The influence of reaction time, initiator concentration and temperature on polymers characteristics was studied. Evaluation of the termination mode in free-radical polymerization was performed by MALDI-TOF mass spectrometry. Termination occurs mainly by disproportionation reaction. Additional peaks in the spectrum were attributed to side chain reactions implying phenoxy radicals. This new polymer exhibits a potential antibacterial activity against Bacillus subtilis by using anti-adhesion and anti-biofilm tests. After an adhesion time of 3 h, compared to a non-coated glass slide, there was a decrease of bacteria of 99% on the polymer coated glass slide. After three days of culture in a bacterial suspension, no biofilm was observed on the polymer coated surface.