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2018 Volume 35 Issue 2
2018, 35(2): 123-128
doi: 10.11944/j.issn.1000-0518.2018.02.170427
Abstract:
Biomacromolecules, such as DNA, protein and virus, can only undergo thermal degradation because their dimensions exceed the range of their intermolecular forces. Hence the formation of solvent-free biomacromolecular liquid and liquid crystal materials remains a significant challenge. Here, we briefly introduce the preparation and characterization of solvent-free biomacromolecular liquid crystal materials. Lamellar mesophases of solvent-free thermotropic liquid crystals are formed by electrostatic complexation of biomacromolecules and oppositely charged surfactants. These thermotropic liquid crystals retain the ordering and fluidity of biomolecules, providing great opportunities for their technical applications in water-free environments.
Biomacromolecules, such as DNA, protein and virus, can only undergo thermal degradation because their dimensions exceed the range of their intermolecular forces. Hence the formation of solvent-free biomacromolecular liquid and liquid crystal materials remains a significant challenge. Here, we briefly introduce the preparation and characterization of solvent-free biomacromolecular liquid crystal materials. Lamellar mesophases of solvent-free thermotropic liquid crystals are formed by electrostatic complexation of biomacromolecules and oppositely charged surfactants. These thermotropic liquid crystals retain the ordering and fluidity of biomolecules, providing great opportunities for their technical applications in water-free environments.
2018, 35(2): 129-136
doi: 10.11944/j.issn.1000-0518.2018.02.170346
Abstract:
Flat panel displays(FPDs) of polymer light-emitting diodes(PLEDs) attract more attention in this field because of the color tunability of polymer materials within the entire visible spectrum, simple solution processability, and suitability for large area and flexible substrates. For the patterning method of polymer light-emitting films, inkjet printing is a potential technique for applications because of its simple and high efficient patterning process, suitability for solution process, flexibility of the patterning process, and easiness to integration and automatization. The deposition of high quality polymer film is essential for fabricating high-performance PLEDs. However, a ring-shaped film is often formed on the substrate due to the "coffee ring" effect in inkjet printing. Therefore, it is essential to eliminate the "coffee ring" effect to achieve uniform deposition of polymer film. In this paper, we review the progress on avoiding "coffee ring" effect to achieve high uniformity of inkjet printing polymer films.
Flat panel displays(FPDs) of polymer light-emitting diodes(PLEDs) attract more attention in this field because of the color tunability of polymer materials within the entire visible spectrum, simple solution processability, and suitability for large area and flexible substrates. For the patterning method of polymer light-emitting films, inkjet printing is a potential technique for applications because of its simple and high efficient patterning process, suitability for solution process, flexibility of the patterning process, and easiness to integration and automatization. The deposition of high quality polymer film is essential for fabricating high-performance PLEDs. However, a ring-shaped film is often formed on the substrate due to the "coffee ring" effect in inkjet printing. Therefore, it is essential to eliminate the "coffee ring" effect to achieve uniform deposition of polymer film. In this paper, we review the progress on avoiding "coffee ring" effect to achieve high uniformity of inkjet printing polymer films.
2018, 35(2): 137-146
doi: 10.11944/j.issn.1000-0518.2018.02.170036
Abstract:
The unique two-dimensional spatial structure gives graphene excellent chemical and physical properties and huge specific surface area, which makes graphene a very promising material for energy storage applications and a research hotspot recently. Irreversible agglomeration, smooth surface and inertness result in the dramatic reduction of the available active surface of graphene, which limits its blending with other materials. In recent years, doping graphene with nitrogen reforms its electronic structure and increases surface active sites, promoting its electrochemical performance in the field of energy storage. This paper reviews the current status of nitrogen-doped graphene synthesis and recent progress in the use of nitrogen-doped graphene in chemical energy storage, including supercapacitors, Li-ion batteries, Li-air batteries and Li-S batteries. Finally, key issues related to preparations and applications of nitrogen-doped graphene are briefly discussed as well, and the development prospect of nitrogen-doped graphene is prospected as well.
The unique two-dimensional spatial structure gives graphene excellent chemical and physical properties and huge specific surface area, which makes graphene a very promising material for energy storage applications and a research hotspot recently. Irreversible agglomeration, smooth surface and inertness result in the dramatic reduction of the available active surface of graphene, which limits its blending with other materials. In recent years, doping graphene with nitrogen reforms its electronic structure and increases surface active sites, promoting its electrochemical performance in the field of energy storage. This paper reviews the current status of nitrogen-doped graphene synthesis and recent progress in the use of nitrogen-doped graphene in chemical energy storage, including supercapacitors, Li-ion batteries, Li-air batteries and Li-S batteries. Finally, key issues related to preparations and applications of nitrogen-doped graphene are briefly discussed as well, and the development prospect of nitrogen-doped graphene is prospected as well.
2018, 35(2): 147-153
doi: 10.11944/j.issn.1000-0518.2018.02.170378
Abstract:
Human islet amyloid polypeptide(hIAPP) is closely associated with type 2 diabetes mellitus(T2DM), which is one of possible pathogenic factors of islet beta cell apoptosis. It has been suggested that the environmental factors(such as metal ions, pH and temperature) have great effects on the aggregation process of hIAPP. In this study, we investigate the influence of copper(Ⅱ) ions on the aggregation of hIAPP and its fragments by a variety of biophysical methods. Atomic force microscope(AFM) and thioflavin T(ThT) fluorescence measurements show that the copper ions can inhibit hIAPP(1~37) and hIAPP(11~28) to aggregate into fibers. In addition, the micro-Fourier transform infrared spectroscopy(Micro-FTIR) shows that copper ions can restrain the transition from alpha helices structure to beta sheets formation during the peptide incubation. By the single amino acid mutation experiment, we speculate that the His18 in hIAPP(11~28) may have a dominant effect on the aggregation behavior and the interaction with copper ions.
Human islet amyloid polypeptide(hIAPP) is closely associated with type 2 diabetes mellitus(T2DM), which is one of possible pathogenic factors of islet beta cell apoptosis. It has been suggested that the environmental factors(such as metal ions, pH and temperature) have great effects on the aggregation process of hIAPP. In this study, we investigate the influence of copper(Ⅱ) ions on the aggregation of hIAPP and its fragments by a variety of biophysical methods. Atomic force microscope(AFM) and thioflavin T(ThT) fluorescence measurements show that the copper ions can inhibit hIAPP(1~37) and hIAPP(11~28) to aggregate into fibers. In addition, the micro-Fourier transform infrared spectroscopy(Micro-FTIR) shows that copper ions can restrain the transition from alpha helices structure to beta sheets formation during the peptide incubation. By the single amino acid mutation experiment, we speculate that the His18 in hIAPP(11~28) may have a dominant effect on the aggregation behavior and the interaction with copper ions.
2018, 35(2): 154-164
doi: 10.11944/j.issn.1000-0518.2018.02.170004
Abstract:
Heterocyclic molecules containing 1, 2, 4-triazole motif are important for drug screening due to their better broad spectrum of bioactivities. For structure-activity relationship study, twenty-eight novel multi-heterocyclic molecules[TM1~TM3(a~f)] and[TM4~TM5(a~e)] containing duo 1, 2, 4-triazole motifs were synthesized by the conjugation with piperazine and s-triazine, respectively. The structures of target molecules were confirmed via infrared(IR), proton nuclear magnetic resonance(1H NMR) and high resolution mass spectrometry(HRMS). In order to investigate the effect of 4-amino substituent on 1, 2, 4-triazole for bioactivities, the comparison between compounds 6-morpholine-2, 4-(5-thioether-4-amino-3-n-pentyl-1, 2, 4-triazole)-1, 3, 5-triazine(C), 6-pyrrole-2, 4-(5-mercapto-4-amino-3-n-pentyl-1, 2, 4-triazole)-1, 3, 5-triazine(D) and target molecules were also performed. The inhibitory activities against cell division cycle protein 25B(Cdc25B) phosphatases of synthesized molecules were evaluated. Twenty one molecules exhibit good activities, and nine among them are more potent than the positive control Na3VO4.
Heterocyclic molecules containing 1, 2, 4-triazole motif are important for drug screening due to their better broad spectrum of bioactivities. For structure-activity relationship study, twenty-eight novel multi-heterocyclic molecules[TM1~TM3(a~f)] and[TM4~TM5(a~e)] containing duo 1, 2, 4-triazole motifs were synthesized by the conjugation with piperazine and s-triazine, respectively. The structures of target molecules were confirmed via infrared(IR), proton nuclear magnetic resonance(1H NMR) and high resolution mass spectrometry(HRMS). In order to investigate the effect of 4-amino substituent on 1, 2, 4-triazole for bioactivities, the comparison between compounds 6-morpholine-2, 4-(5-thioether-4-amino-3-n-pentyl-1, 2, 4-triazole)-1, 3, 5-triazine(C), 6-pyrrole-2, 4-(5-mercapto-4-amino-3-n-pentyl-1, 2, 4-triazole)-1, 3, 5-triazine(D) and target molecules were also performed. The inhibitory activities against cell division cycle protein 25B(Cdc25B) phosphatases of synthesized molecules were evaluated. Twenty one molecules exhibit good activities, and nine among them are more potent than the positive control Na3VO4.
2018, 35(2): 165-173
doi: 10.11944/j.issn.1000-0518.2018.02.170045
Abstract:
Donor-acceptor type polymers are new electrochromic materials which are tunable and colorfull. However, the electrochromic properties such as optical contrast and stability need to be further improved. Low band gap conjugated polymers containing diketopyrrolopyrrole(DPP), benzothiadiazole(BTZ) and thiophen (T) were synthesized and their electrochromic properties were studied. Four polymers P1~P4 were obtained by adjusting the molar ratio of the three monomers(n(DPP):n(BTZ):n(T)=1:0:1, 1.5:0.5:1, 2:1:1 and 3:2:1, respectively). The absorption and electrochromic properties of the polymers depend on the ratios of DPP, BTZ and T units in the polymers. It was found that these polymers have high optical contrast(△T:50%~60%) and coloration efficiency(CE:300~600 cm2/C) in the near-infrared region. In particular, △T of polymer P3 reached the high value of 63% and CE of polymer P4 was 471 cm2/C at 1550 nm. The polymers containing BTZ groups have higher optical contrast at both the near-infrared(NIR) region and the maximum absorption wavelength than that of polymer P1 in which the BTZ content is zero. Polymers containing BTZ unit shows better electrochromic stability, which is attributed to its higher oxidation potential and better electrochemical stability. It provides a new way to design high-performance electrochromic polymers.
Donor-acceptor type polymers are new electrochromic materials which are tunable and colorfull. However, the electrochromic properties such as optical contrast and stability need to be further improved. Low band gap conjugated polymers containing diketopyrrolopyrrole(DPP), benzothiadiazole(BTZ) and thiophen (T) were synthesized and their electrochromic properties were studied. Four polymers P1~P4 were obtained by adjusting the molar ratio of the three monomers(n(DPP):n(BTZ):n(T)=1:0:1, 1.5:0.5:1, 2:1:1 and 3:2:1, respectively). The absorption and electrochromic properties of the polymers depend on the ratios of DPP, BTZ and T units in the polymers. It was found that these polymers have high optical contrast(△T:50%~60%) and coloration efficiency(CE:300~600 cm2/C) in the near-infrared region. In particular, △T of polymer P3 reached the high value of 63% and CE of polymer P4 was 471 cm2/C at 1550 nm. The polymers containing BTZ groups have higher optical contrast at both the near-infrared(NIR) region and the maximum absorption wavelength than that of polymer P1 in which the BTZ content is zero. Polymers containing BTZ unit shows better electrochromic stability, which is attributed to its higher oxidation potential and better electrochemical stability. It provides a new way to design high-performance electrochromic polymers.
2018, 35(2): 174-180
doi: 10.11944/j.issn.1000-0518.2018.02.170056
Abstract:
Cross-linking is a commonly used method for polyolefin modification to improve the material's mechanical properties, thermo-and chemical resistance. High molecular mass(Mw) iPPs containing reactive anthracene groups were synthesized by coordination copolymerization. Crosslinked iPP films could be prepared by adding bi-functional N, N'-1, 4-phenylene bismaleimide as a crosslinker to react with the pendent anthracene groups during the solvent casting process of the film. The cross-linking degree of the films could be easily tuned by the addition of the crosslinker. Characteristic absorption bands in Fourier transform infrared(FT-IR) spectra of the crosslinked films and gravimetric analysis of the insoluble portion could be used to determine the crosslinking degree. Differential scanning calorimetry(DSC) and wide-angle X-ray diffraction(WAXD) analysis revealed that the crystallinity and crystallization capability of the films decreased followed with the increase of cross-linking degree, which were mainly caused by the restricted chain movement. On the other hand, according to DMA analysis, the loss modulus dropped gradually with the increase of cross-linking degree, indicating the loss of toughness brought by cross-linking. The increased Tg detected from loss angle curves indicated the enhancement of thermoresistance. The tensile stress of the crosslinked iPP films were improved by forming polymer network containing more force bearing point, while the elongation at break dropped drastically because of the chains' poor movability.
Cross-linking is a commonly used method for polyolefin modification to improve the material's mechanical properties, thermo-and chemical resistance. High molecular mass(Mw) iPPs containing reactive anthracene groups were synthesized by coordination copolymerization. Crosslinked iPP films could be prepared by adding bi-functional N, N'-1, 4-phenylene bismaleimide as a crosslinker to react with the pendent anthracene groups during the solvent casting process of the film. The cross-linking degree of the films could be easily tuned by the addition of the crosslinker. Characteristic absorption bands in Fourier transform infrared(FT-IR) spectra of the crosslinked films and gravimetric analysis of the insoluble portion could be used to determine the crosslinking degree. Differential scanning calorimetry(DSC) and wide-angle X-ray diffraction(WAXD) analysis revealed that the crystallinity and crystallization capability of the films decreased followed with the increase of cross-linking degree, which were mainly caused by the restricted chain movement. On the other hand, according to DMA analysis, the loss modulus dropped gradually with the increase of cross-linking degree, indicating the loss of toughness brought by cross-linking. The increased Tg detected from loss angle curves indicated the enhancement of thermoresistance. The tensile stress of the crosslinked iPP films were improved by forming polymer network containing more force bearing point, while the elongation at break dropped drastically because of the chains' poor movability.
2018, 35(2): 181-188
doi: 10.11944/j.issn.1000-0518.2018.02.170099
Abstract:
A visible-light-induced dearomation cyclilation of N-benzylmethacrylamides with nonafluorinated alkyl bromides or iodides toward nonafluorinated azaspirocyclic cyclo-hexadienones was developed. Under the irradiation of blue light-emitting diode(LED) light, using fac-Ir(ppy)3(fac=facial, ppy=2-phenylpyridyl) as the photocatalyst, N-benzylmethacrylamides and nonafluorinated alkyl bromides or iodides underwent cascade dearomation/cyclilation under optimal conditions, leading to a series of perfluorinating azaspirocyclic cyclohexadienones in 61%~85% yield, as well as introducing a series of perfluorinated moieties including CF3, C3F7, C4F9, C6F13, C8F17, CH2CF2, CF2CO2Et(Et:Ethyl). Given the broad substrate scope, mild reaction conditions and green catalytic systems, this protocol provides a green, effective and quick approach to pharmaceutically important cyclohexadienones.
A visible-light-induced dearomation cyclilation of N-benzylmethacrylamides with nonafluorinated alkyl bromides or iodides toward nonafluorinated azaspirocyclic cyclo-hexadienones was developed. Under the irradiation of blue light-emitting diode(LED) light, using fac-Ir(ppy)3(fac=facial, ppy=2-phenylpyridyl) as the photocatalyst, N-benzylmethacrylamides and nonafluorinated alkyl bromides or iodides underwent cascade dearomation/cyclilation under optimal conditions, leading to a series of perfluorinating azaspirocyclic cyclohexadienones in 61%~85% yield, as well as introducing a series of perfluorinated moieties including CF3, C3F7, C4F9, C6F13, C8F17, CH2CF2, CF2CO2Et(Et:Ethyl). Given the broad substrate scope, mild reaction conditions and green catalytic systems, this protocol provides a green, effective and quick approach to pharmaceutically important cyclohexadienones.
2018, 35(2): 189-196
doi: 10.11944/j.issn.1000-0518.2018.02.170066
Abstract:
As a widely used class of privileged ligands, phosphinoaryloxazolines(PHOX) have attracted much attention from chemists. However, the previous synthetic methods have problems of long steps, low yield and difficult separation and so on. In this article, a simple and efficient procedure for the synthesis of phosphinoaryloxazolines(PHOX) has been developed. First, 2-(diphenylphosphino)benzoic acid was condensed with various enantiomerically pure amino alcohols in the presence of 1-hydroxylbenzotriazole(HOBt) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride(EDCI) in dimethylformamide to give the corresponding (amido alcohol)s amides in excellent yields. Then the (amido alcohol)s amides were subjected to the oxazoline ring formation by treatment with triphenylphosphine, triethylamine and carbon tetrachloride in acetonitrile to afford a series of phosphinooxazolines in 64%~86% total yields. Subsequently, (S)-t-BuPHOX was applied in the palladium-catalyzed decarboxylative Tsuji allylations of β-ketoester, giving an excellent isolated yield of 80% with an enantiomeric excess of 84%. The new synthetic procedure has the advantages of using readily available starting materials, mild reaction conditions, and high overall yields.
As a widely used class of privileged ligands, phosphinoaryloxazolines(PHOX) have attracted much attention from chemists. However, the previous synthetic methods have problems of long steps, low yield and difficult separation and so on. In this article, a simple and efficient procedure for the synthesis of phosphinoaryloxazolines(PHOX) has been developed. First, 2-(diphenylphosphino)benzoic acid was condensed with various enantiomerically pure amino alcohols in the presence of 1-hydroxylbenzotriazole(HOBt) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride(EDCI) in dimethylformamide to give the corresponding (amido alcohol)s amides in excellent yields. Then the (amido alcohol)s amides were subjected to the oxazoline ring formation by treatment with triphenylphosphine, triethylamine and carbon tetrachloride in acetonitrile to afford a series of phosphinooxazolines in 64%~86% total yields. Subsequently, (S)-t-BuPHOX was applied in the palladium-catalyzed decarboxylative Tsuji allylations of β-ketoester, giving an excellent isolated yield of 80% with an enantiomeric excess of 84%. The new synthetic procedure has the advantages of using readily available starting materials, mild reaction conditions, and high overall yields.
2018, 35(2): 197-205
doi: 10.11944/j.issn.1000-0518.2018.02.170129
Abstract:
Two novel 1, 3-selenazole carbonyl hydrazones(SAF1, SAF2) were synthesized and their structures were confirmed by infrared spectrometry and nuclear magnetic resonance. Monitoring of nine common anions using probes SAF1 and SAF2 was performed via ultraviolet-visible and fluorescent spectra. When acetate ions(AcO-) were added, a new absorption peak of SAF1 and SAF2 was found at 500 nm and 414 nm, respectively. The color of SAF1 and SAF2 solutions changed from pale yellow to red and yellow, respectively. These results show naked eye identification of AcO-. In fluorescent spectra, a strong emission peak at 417 nm is found with the turn-on effect. The lowest limit of detection for AcO- reaches 10-5 mol/L. The binding constants of SAF1 and SAF2 with AcO- are 3.03×104 and 1.42×104 L/mol, respectively. SAF1 and SAF2 are expected to be specific fluorescent probes toward AcO-.
Two novel 1, 3-selenazole carbonyl hydrazones(SAF1, SAF2) were synthesized and their structures were confirmed by infrared spectrometry and nuclear magnetic resonance. Monitoring of nine common anions using probes SAF1 and SAF2 was performed via ultraviolet-visible and fluorescent spectra. When acetate ions(AcO-) were added, a new absorption peak of SAF1 and SAF2 was found at 500 nm and 414 nm, respectively. The color of SAF1 and SAF2 solutions changed from pale yellow to red and yellow, respectively. These results show naked eye identification of AcO-. In fluorescent spectra, a strong emission peak at 417 nm is found with the turn-on effect. The lowest limit of detection for AcO- reaches 10-5 mol/L. The binding constants of SAF1 and SAF2 with AcO- are 3.03×104 and 1.42×104 L/mol, respectively. SAF1 and SAF2 are expected to be specific fluorescent probes toward AcO-.
2018, 35(2): 206-215
doi: 10.11944/j.issn.1000-0518.2018.02.170084
Abstract:
As the photocatalytic reaction has the advantages of non-pollution, safe and efficient, so it has become a research hotspot of environmental protecting field. Therefore, this work choose 2, 4-two (3, 5-two methyl pyrazole)-6-two ethyl amine-1, 3, 5-three triazine(L1) and 2, 6-di[3-(5-methylpyrazolyl)] pyridine(L2) as the ligands, RuCl3 as the metal source to synthesize three kinds of complexes, [Ru(L1)Cl3](1), [Ru(L2)2]·Cl3(2), and[Ru(L2)2]·(H2BTC)·(HBTC)·H2O(3). At the same time, the complexes were characterized by infrared(IR) spectrometry, ultraviolet-visible(UV-Vis), themogravimetry(TG) and X-ray diffraction, and the photocatalytic degradation of RhB was explored. The results show that the complexes 1~3 have a certain degree of photodegradation effect, the degradation efficiency is 46.8%, 44.7% and 40.4%, respectively. Under the same conditions, the degradation effects of the complexes are better than those corresponding only with metal salts, ligands and H2O2, respectively.
As the photocatalytic reaction has the advantages of non-pollution, safe and efficient, so it has become a research hotspot of environmental protecting field. Therefore, this work choose 2, 4-two (3, 5-two methyl pyrazole)-6-two ethyl amine-1, 3, 5-three triazine(L1) and 2, 6-di[3-(5-methylpyrazolyl)] pyridine(L2) as the ligands, RuCl3 as the metal source to synthesize three kinds of complexes, [Ru(L1)Cl3](1), [Ru(L2)2]·Cl3(2), and[Ru(L2)2]·(H2BTC)·(HBTC)·H2O(3). At the same time, the complexes were characterized by infrared(IR) spectrometry, ultraviolet-visible(UV-Vis), themogravimetry(TG) and X-ray diffraction, and the photocatalytic degradation of RhB was explored. The results show that the complexes 1~3 have a certain degree of photodegradation effect, the degradation efficiency is 46.8%, 44.7% and 40.4%, respectively. Under the same conditions, the degradation effects of the complexes are better than those corresponding only with metal salts, ligands and H2O2, respectively.
2018, 35(2): 216-223
doi: 10.11944/j.issn.1000-0518.2018.02.170106
Abstract:
Controling the morphology of the perovskite film is an effective way to improve the photoelectric conversion efficiency of the cells. In this work, 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide(EMITFSI), 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide(HMITFSI) and 1-ethyl-3-methy-limidazolium bis(fluorosulfonyl) imide(EMIFSI) were prepared. Perovskite active layers were dealed with ionic liquid dispersed into the chlorobenzene solution, the morphology of the perovskite layer and the performance of perovskite solar cells were investigated. The results indicate that the fill factor of perovskite solar cells dealed with HMITFSI is enhanced from 0.71 to 0.74, and the photoelectric conversion efficiency is increased, and that the morphology of perovskite is also improved. However, the performance of perovskite solar cells dealed with EMITFSI and EMIFSI are declined. It is HMI cation that improves the morphology of perovskite.
Controling the morphology of the perovskite film is an effective way to improve the photoelectric conversion efficiency of the cells. In this work, 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide(EMITFSI), 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide(HMITFSI) and 1-ethyl-3-methy-limidazolium bis(fluorosulfonyl) imide(EMIFSI) were prepared. Perovskite active layers were dealed with ionic liquid dispersed into the chlorobenzene solution, the morphology of the perovskite layer and the performance of perovskite solar cells were investigated. The results indicate that the fill factor of perovskite solar cells dealed with HMITFSI is enhanced from 0.71 to 0.74, and the photoelectric conversion efficiency is increased, and that the morphology of perovskite is also improved. However, the performance of perovskite solar cells dealed with EMITFSI and EMIFSI are declined. It is HMI cation that improves the morphology of perovskite.
2018, 35(2): 224-231
doi: 10.11944/j.issn.1000-0518.2018.02.170080
Abstract:
Different mass fraction of iron-containing silicon carbide(Fe/SiC) ceramics was successfully prepared by firstly synthesizing iron(Fe)-containing precursor via blending Fe colloids formed by the reaction of liquid polycarbosilane(PCS) and carbonyl iron with solid PCS and then the cross-linking and pyrolysis. The effects of the introduction of Fe on the component, structure, and magnetic and dielectric properties were systematically studied. When the mass fraction of iron is less than 8.94%, Fe element can significantly promote the decomposition of SiCxOy and generate β-SiC, and the crystallization peak of β-SiC is sharper with increased Fe. But when the Fe mass fraction increases to 11.78%, the main product is Fe3Si; Fe-SiC ceramics are all ferromagnetic, and their saturation magnetization increases exponentially with the increase of iron. Fe/SiC ceramic with 4.19% Fe has a minimum -9.4 dB reflection loss at 12.4 GHz. The bandwidths of less than -5 dB for Fe/SiC cermic with 4.19% and 8.94% Fe are 2.4 GHz and 3.7 GHz, respectively, which can be used as good microwave-absorption materials.
Different mass fraction of iron-containing silicon carbide(Fe/SiC) ceramics was successfully prepared by firstly synthesizing iron(Fe)-containing precursor via blending Fe colloids formed by the reaction of liquid polycarbosilane(PCS) and carbonyl iron with solid PCS and then the cross-linking and pyrolysis. The effects of the introduction of Fe on the component, structure, and magnetic and dielectric properties were systematically studied. When the mass fraction of iron is less than 8.94%, Fe element can significantly promote the decomposition of SiCxOy and generate β-SiC, and the crystallization peak of β-SiC is sharper with increased Fe. But when the Fe mass fraction increases to 11.78%, the main product is Fe3Si; Fe-SiC ceramics are all ferromagnetic, and their saturation magnetization increases exponentially with the increase of iron. Fe/SiC ceramic with 4.19% Fe has a minimum -9.4 dB reflection loss at 12.4 GHz. The bandwidths of less than -5 dB for Fe/SiC cermic with 4.19% and 8.94% Fe are 2.4 GHz and 3.7 GHz, respectively, which can be used as good microwave-absorption materials.
2018, 35(2): 232-238
doi: 10.11944/j.issn.1000-0518.2018.02.170083
Abstract:
In order to obtain large-area graphene oxide(L-GO) films, a series of FeCl3-catalyzed L-GO films are prepared. The surface morphology and structure of L-GO films synthesized with various temperatures and times are studied by atomic force microscope(AFM), polarizing microscope(POM), Fourier transform infrared spectrometer(FTIR), and X-ray diffraction(XRD). The sheet domain area of FeCl3-catalyzed L-GO films is 10 μm×10 μm, which increases about four times in contrast to that of GO films prepared without catalyst. By further analysis of FTIR and XRD, the formation of L-GO domains can be attributed to the new connections of the hydroxyl, carboxyl, and carbonyl groups in graphene oxide under FeCl3 catalysis. Thus, a formation model of FeCl3-catalyzed L-GO films is proposed, which provides a new way for the preparation of large area graphene oxide films.
In order to obtain large-area graphene oxide(L-GO) films, a series of FeCl3-catalyzed L-GO films are prepared. The surface morphology and structure of L-GO films synthesized with various temperatures and times are studied by atomic force microscope(AFM), polarizing microscope(POM), Fourier transform infrared spectrometer(FTIR), and X-ray diffraction(XRD). The sheet domain area of FeCl3-catalyzed L-GO films is 10 μm×10 μm, which increases about four times in contrast to that of GO films prepared without catalyst. By further analysis of FTIR and XRD, the formation of L-GO domains can be attributed to the new connections of the hydroxyl, carboxyl, and carbonyl groups in graphene oxide under FeCl3 catalysis. Thus, a formation model of FeCl3-catalyzed L-GO films is proposed, which provides a new way for the preparation of large area graphene oxide films.
2018, 35(2): 239-244
doi: 10.11944/j.issn.1000-0518.2018.02.170053
Abstract:
Through regulating the amount of PtCl2 and the temperature of reduction, Ru@Pt core-shell monodisperse nanoparticles comprising a Ru core covered with an approximately 1.5 monolayer-thick shell of Pt atoms were synthesized by using a sequential polyol process with RuCl3·xH2O and PtCl2 as precursors, ethylene glycol as the reductant and polyvinylpyrrolidone as the stabilizer. The microstructure, size-distribution, crystal structure and phase composition of nanoparticles were characterized by transmission electron microscopy(TEM), X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS) and other analytical methods. The results indicate that the nanoparticles are uniformly distributed and spherical with 3.57 nm average size. The core is about 2.49 nm and the shell is about 0.55 nm. Pt shell has a nice crystalline phase which is mainly {111} lattice fringes. The production of electronic effect is found between Ru core and Pt shell, and this makes the diffraction peak of Pt and the electron binding energy of Ru and Pt produce a certain offset. The factors controlling the thickness of the shell of nanoparticles and strengthening the electronic effect between Ru core and Pt shell have been investigated preliminarily. The Ru@Pt core-shell nanoparticles are expected to have great potential in catalysis and other fields.
Through regulating the amount of PtCl2 and the temperature of reduction, Ru@Pt core-shell monodisperse nanoparticles comprising a Ru core covered with an approximately 1.5 monolayer-thick shell of Pt atoms were synthesized by using a sequential polyol process with RuCl3·xH2O and PtCl2 as precursors, ethylene glycol as the reductant and polyvinylpyrrolidone as the stabilizer. The microstructure, size-distribution, crystal structure and phase composition of nanoparticles were characterized by transmission electron microscopy(TEM), X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS) and other analytical methods. The results indicate that the nanoparticles are uniformly distributed and spherical with 3.57 nm average size. The core is about 2.49 nm and the shell is about 0.55 nm. Pt shell has a nice crystalline phase which is mainly {111} lattice fringes. The production of electronic effect is found between Ru core and Pt shell, and this makes the diffraction peak of Pt and the electron binding energy of Ru and Pt produce a certain offset. The factors controlling the thickness of the shell of nanoparticles and strengthening the electronic effect between Ru core and Pt shell have been investigated preliminarily. The Ru@Pt core-shell nanoparticles are expected to have great potential in catalysis and other fields.
