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排序方式: 共有1421条查询结果,搜索用时 15 毫秒
51.
In this study, a novel azocalix[4]arene derivative, 5,11,17-tris[(1-naphtyl)azo]-25,26,27,28-tetrahydroxy-calix[4]arene (NAC4) bearing napthyl groups on the upper rim was synthesized. Its complexation behavior for alkali, alkaline-earth and various heavy metal ions (Li+, Na+, K+, Rb+, Cs+, Mg2+, Ca2+, Sr2+, Ba2+, Pb2+, Hg2+, Ni2+, Cd2+, Cu2+, Zn2+, Co2+, Fe2+, Cr3+, Ag+) was investigated by spectroscopic and voltammetric methods. This chemosensor exhibits decreased absorbance in the presence of Hg2+ and a unique absorbance quenching effect only for Cr3+. In addition, a new absorption band centered at 565 nm with the formation of the 1:1 host–guest complex (Cr3+-NAC4) was observed in the case of Cr3+, leading to an obvious color change from light orange to dark lilac. In voltammetric experiments, Cr3+ ions decreased voltammetric peaks of NAC4, whereas no significant changes occurred in the presence of the other metal ions. The Benesi–Hildebrand method was used to determine a logarithmic value of 3.76 for the association constant of the complex between Cr3+ and NAC4. 相似文献
52.
Süleyman Köytepe Maruf Hurşit Demirel Ahmet Gültek Turgay Seçkin 《Polymer International》2014,63(4):778-787
In this study, novel metallo‐supramolecular materials based on terpyridine‐functionalized polyhedral silsesquioxane were synthesized from 4′‐chloro‐2,2′:6′,2″‐terpyridine and amino‐group‐functionalized polyhedral oligomeric silsesquioxane. The obtained terpyridine‐functionalized polyhedral silsesquioxanes were converted to metallo‐supramolecular hybrid materials by coordination polycondensation reaction with Co(II) or Cu(II) ions. The supramolecular polymers created were characterized by means of structure, morphology and stimuli‐responsive performance employing scanning electron microscopy, amperometric techniques and UV–visible and Fourier transform IR spectroscopy. UV?visible and cyclic voltammetry studies showed that both the optical and electrochemical properties of metallo‐supramolecular materials are affected by the substituent at the pyridine periphery. The supramolecular polymers obtained exhibited electrochromism during the oxidation processes of cyclic voltammogram studies. As a result, these terpyridine‐functionalized polyhedral silsesquioxanes are good candidates for electronic, opto‐electronic and photovoltaic applications as smart stimuli‐responsive materials. © 2013 Society of Chemical Industry 相似文献
53.
Erkan Ertürk Mustaf Ali Tezeren Tahir Tilki Tuba Erdogan Ahmet C Gren 《Polymer International》2012,61(5):795-799
The readily available mixed‐valent iron trifluoroacetate complex [Fe2IIIFeII(µ3‐O)(O2CCF3)6(H2O)3] is an effective catalyst for the polymerization of epoxides. A very small amount of the catalyst (1.0–0.01 mol%) could initiate the polymerization of cyclohexene oxide, cyclopentene oxide and epichlorohydrin. Based on quantitative end‐group analysis by 19F NMR spectroscopy, a Lewis acid (LA⊕) catalyzed anionic reaction mechanism is proposed. Copyright © 2012 Society of Chemical Industry 相似文献
54.
Tuncay Tun? ?brahim Uslu ?enol Durmu?o?lu Selda Keskin Arda Aytimur Ahmet Akdemir 《Journal of Inorganic and Organometallic Polymers and Materials》2012,22(1):105-111
In this study, boron doped and undoped poly (vinyl) alcohol/bismuth–gadolina acetate (PVA/Bi–Gd) nanofibers were prepared
using electrospinning technique then calcinated at 800 °C for 2 h. The originality of this study is the addition of boron
to metal acetates. The effects of boron doping were investigated in terms of solution properties, morphological changes and
thermal characteristics. The characteristics of the fibers were investigated with FT-IR, XRD, SEM and BET. The addition of
boron did not only increase the thermal stability of the fibers, but also their diameters, which yielded stronger fibers.
XRD analyses showed that boron doping increased the peak intensities and indicated that the boron doping enhanced the crystallite
size. Moreover, no shifts were noticed in diffraction angles for boron doped and undoped samples. Therefore, boron doping
did not significantly alter the lattice spacing. The SEM micrograph of the fibers showed that the addition of boron resulted
in the formation of cross-linked bright-surfaced fibers. The average fiber diameter for boron doped and undoped fiber mats
were 204 and 123 nm, respectively. Also, grain diameters of boron doped and undoped nanocrystalline sintered powders were
measured as 140 and 118 nm, respectively. The BET results showed that boron undoped and doped Bi2O3–La2O3 nanocrystalline powder ceramic structures sintered at 800 °C have surface areas of 59.72 and 39.80 m2/g, respectively. 相似文献
55.
The production of pure powder samples of boron-rich ternary Al–B–C phases was investigated in vacuum at temperatures between 1400 °C and 1600 °C, using a range of different starting powders. Compacted powder mixes of B–AlB2–B4C, Al–B–C, Al–B–B4C, B–C–AlB2, B–AlB2 and Al–B were heated for 1–2 h under vacuum in a carbon resistance furnace and the products characterised by X-ray diffraction. It was found impossible to produce significant quantities of C4AlB24 under these conditions, but >95% pure samples of α-AlB12, AlB12C2 and Al3B48C2 were obtained. This study is a precursor to further research aimed at producing dense B4C-type materials which might offer the advantages of easier densification and fabrication as compared with B4C itself. 相似文献
56.
A series of poly(styrene-co-p-stearoyl styrene) copolymers as novel polymeric solid–solid phase-change materials (SSPCMs) were synthesized by the modification of polystyrene with stearoyl chloride. The chemical structure and crystalline morphology of the synthesized copolymers were determined with Fourier transform infrared spectroscopy and polarized optical microscopy, respectively. The thermal energy storage properties and thermal stability of the SSPCMs were investigated with differential scanning calorimetry and thermogravimetric analysis, respectively. In addition, the thermal conductivity of the SSPCMs was measured with a thermal property analyzer. Moreover, thermal cycling tests showed that the copolymers had good thermal reliability and chemical stability after being subjected to 5000 heating/cooling cycles. The synthesized poly(styrene-co-stearoyl styrene) copolymers as novel SSPCMs have considerable potential for thermal energy storage and temperature-control applications. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
57.
Ahmet Surucu Volkan Eyupoglu Osman Tutkun 《Journal of Industrial and Engineering Chemistry》2012,18(2):629-634
Cobalt and nickel are among the most important nonferrous metals. The using of flat sheet supported liquid membranes (FSSLMs) to remove metals from wastewaters has been used actively by the scientific and industrial communities. In this study, the selective separation of cobalt from thiocyanate solutions containing cobalt and nickel by FSSLM was examined using tri-n-octylamine (Alamine 300) as carrier. The FSSLM was consisted of extractant, flat sheet support and organic solvent. The various parameters were studied to determine the optimum extraction and striping conditions of cobalt and nickel. These parameters were stirring speeds of phases, NH4SCN concentration, pH, diluent type, extractant concentration, stripping reagent concentration and modifier concentration. Concentration of cobalt and nickel were determined by Shimadzu AA-6701GF spectrophotometer. In the optimum conditions, selective separation of cobalt was achieved with an efficiency of 98.4% within 8 h, for equimolar feed mixtures, 400 mg/L Co + 400 mg/L Ni, and the separation factor of Co(II) over Ni(II) was 234.4. In addition, for nonequimolar feed mixtures, 500 mg/L Co + 1000 mg/L Ni, Ni in excess, selective separation of cobalt was 99.9%, and the separation factor of Co was 506 in the same time. 相似文献
58.
Huseyin Avci Esra Akkulak Hazal Gergeroglu Hamed Ghorbanpoor Onur Uysal Ayla Eker Sariboyaci Bahar Demir Merve Nur Soykan Suat Pat Reza Mohammadigharehbagh Ceren Özel Ahmet Cabuk Fatma Doğan Güzel 《应用聚合物科学杂志》2020,137(26):49184
Among the thermoplastic elastomers that play important roles in the polymer industry due to their superior properties, styrene-based species and polyurethane block copolymers are of great interest. Poly(styrene-ethylene-butadiene-styrene) (SEBS) as a triblock copolymer seems to have the potential to meet many demands in different applications due to various industrial requirements where durability, biocompatibility, breaking elongation, and interfacial adhesion are important. In this study, the SEBS triblock copolymer was functionalized with natural (Satureja hortensis, SH) and synthetic (nanopowder, TiO2) agents to obtain composite nanofibers by electrospinning and electrospraying methods for use in biomedical and water filtration applications. The results were compared with thermoplastic polyurethane (TPU) composite nanofibers, which are commonly used in these fields. Here, functionalized SEBS nanofibers exhibited antibacterial effect while at the same time improving cell viability. In addition, because of successful water filtration by using the SEBS composite nanofibers, the material may have a good potential to be used comparably to TPU for the application. 相似文献
59.
60.
Metalloporphyrazines with a 2-methyl-2-pentenyl group fused to each pyrrole unit were synthesized starting with the corresponding unsaturated dicarbonitrile derivative. The new compounds were characterized by elemental analysis together with FTIR, 1H-NMR, and UV-Vis spectroscopy and via voltammetric and spectrochemical methods. Electrochemical and spectroelectrochemical measurements demonstrate that while metal-free and magnesium porphyrazines gave common porphyrazine (Pz) ring-based electron-transfer reactions, incorporating redox active metal center, CoII, into the porphyrazine core extended the redox activity of the ring system with reversible metal-based reduction and oxidation couples of the metal center in addition to the common Pz ring-based electron transfer processes. The unsaturated functional groups of the porphyrazines did not alter the common electrochemical behavior of the complexes. An in situ electrocolorimetric method, based on the 1931 CIE (Commission Internationale de l’Eclairage) system of colorimetry, was applied to investigate the color of the electro-generated anionic and cationic forms of the complexes for possible electrochromatic applications. 相似文献