Synthesis, characterization and some properties of novel bis(pentafluorophenyl)methoxyl substituted metal free and metallophthalocyanines

The preparation of some new tetrakis[bis(pentafluorophenyl)methoxyl] substituted metal free and metallophthalocyanine (MPcs) complexes were achieved by the tetramerization of 4-[bis(pentafluorophenyl)methoxy]phthalonitrile with Li metal in pentan-1-ol or metal [Co(II) or Zn(II)] acetates in DMAE, respectively. The structures of the target compounds were confirmed by elemental analysis, IR, UV–vis, ¹H NMR, ¹⁹F NMR and mass spectroscopic methods. MPcs are soluble only in strong and medium polar solvents while the metal free one is soluble in weakly, medium and strong polar solvents. The temperature and frequency dependence of the electrical conductivities were studied on spin coated films of the compounds using dc and impedance spectroscopy techniques in the frequency range from 40 to 10⁵ Hz and within the temperature range from 290 to 440 K. The temperature dependence of the exponent s and conductivity, σ_ac, were completely in agreement with the prediction of the hopping model. The redox properties of the complexes were determined by cyclic voltammetry. The nature of the redox processes was also confirmed using spectroelectrochemical measurements.     

Effects on the thermal expansion coefficient and dielectric properties of CLST/PTFE filled with modified glass fiber as microwave material

The CLST/PTFE/5%GF composite sharply decreases the CTE in both X&Y and Z directions, obtained a promising microwave dielectric material for microwave communication.     

混合相二氧化钛石墨烯复合物的制备及光催化性能

采用水热法制备了一系列混合相二氧化钛-石墨烯(TrG)的复合物, 并考察了石墨烯的用量对降解污染物甲基蓝的影响. 采用X射线衍射(XRD), 傅里叶变换红外(FTIR)光谱, 高分辨透射电镜(HRTEM), 拉曼光谱,紫外-可见漫反射吸收光谱(UV-Vis DRS), X射线光电子能谱(XPS)和比表面积(BET)等测试手段对复合材料进行表征. 结果表明, 复合材料中TiO₂为棒状的混合相, 且均匀分散在石墨烯表面. 由于石墨烯良好的吸光性能,混合相中的异质结和复合物的良好光电子传递能力以及高比表面积, 复合材料具有较高的光催化活性. 所制备的TrG复合材料在紫外光下降解甲基蓝的催化活性均高于纯TiO₂, 且当氧化石墨烯负载量为0.8% (质量分数,w)时, 复合材料TrG具有较好的光催化效果.     

玻璃纤维对聚甲醛基导电复合材料性能的影响

采用在转矩流变仪中熔融混合的方法制备了聚甲醛(POM)/多壁碳纳米管(MWCNTs)/玻璃纤维(GF)和POM/炭黑(CB)/GF复合材料,研究了GF的加入对复合材料的导电性能、结晶行为和动态力学性能的影响.采用场发射扫描电镜(FESEM)观察了复合材料中导电填料的分散状态,发现GF的加入对MWCNTs和CB的分散状态没有明显影响.虽然GF为导电惰性填料,但因其加入起到了占位作用,明显提高了导电填料的有效浓度,从而使复合材料的体积电阻率明显降低.采用示差扫描量热仪(DSC)研究了复合材料中POM的结晶行为,发现GF的加入对POM的结晶温度、熔点和结晶度均无明显影响.采用动态机械分析仪(DMA)对复合材料的动态力学性能进行了研究,表明GF的加入能够明显地提高复合材料的储能模量.     

聚苯胺-还原氧化石墨烯复合材料的比电容及超级电容性能

Flaky polyaniline-reduced graphene oxide (PANI-rGO) composites have larger specific capacitance due to the improved redox charge of PANI in the composites, fabricated by simultaneous reduction of PANI-GO. The structural and morphological analyses were carried out using scanning electron microscopy, UV-Vis spectroscopy, and thermogravimetry. The results showed that the composites are flaky in shape. PANI is uniformly coated on GO, and PANI-rGO has specific capacitance as high as 1069 F·g^-1 (1.71 F·cm^-2) at a current density of 20 A·g^-1, 5 times higher than PANI-GO; this is caused by the large surface and conductivity of the rGO in the composite.     

A novel technique for the interfacial characterisation of glass fibre–polypropylene systems

In the present work, a new technique was developed to determine the interfacial properties of two opaque glass fibre/polypropylene (GF/PP) systems via fragmentation tests on single filament model composites. Fragmentation tests usually require the fibre inside the composites to be completely aligned in the loading direction. Since PP matrices are non-transparent, it is not possible to guarantee a priori this condition. Hence, a novel technique was developed to determine the inclination of the filaments embedded in the composites. The fibre–polymer systems were also evaluated by comparing their interfacial properties with the overall mechanical properties determined on pultruded GF/PP composites. The present work shows that the knowledge of the interfacial properties is important, not only to compare alternative fibre/matrix systems, but also to assess whether the level of adhesion in these systems is adequate to fabricate composites with good mechanical properties.     

纤维状填料/HDPE复合体系的导电渗流与流变渗流行为的关系

研究了纤维状导电材料不锈钢纤维(SSF)填充高密度聚乙烯(HDPE)导电复合体系的导电渗流与流变渗流行为之间的关系,并与颗粒状导电颗粒炭黑(CB)/HDPE导电复合体系进行了比较.发现当SSF含量极低(0.3vol%)时,SSF/HDPE体系即发生导电渗流现象,且导电渗流转变区域极窄;而仅当SSF含量达到4.8vol%时,该复合体系才表现出流变渗流现象,这一结果与CB/HDPE体系及纳米级导电纤维填充体系截然不同.此外,通过正温度系数效应的研究发现SSF形成的导电通路稳定性高于CB/HDPE体系.我们认为,SSF/HDPE体系呈现的这些特点均与SSF较大的直径及长径比且其导电通路及流变渗流网络的形成机理不同有关.     

1,3,2-Diazastanna-[3]ferrocenophanes bearing alkyn-1-yl groups at tin and their 1,1-organoboration with triethylborane—molecular structure of a novel spirotin compound

2,2-Dichloro-1,3-bis(trimethylsilyl)-1,3,2-diazastanna-[3]ferrocenophane (3) reacts with lithium alkynides LiCCR¹ to give the corresponding di(alkyn-1-yl)tin derivatives 4a (R¹=^tBu) and 4b (R¹=SiMe₃). 1,1-Organoboration of 4 with triethylborane affords the spirotin compounds 5 which contain both a ferrocenophane and a stannacyclopentadiene ring. The crystal structure of 5b was determined by X-ray analysis. The compounds 4 and 5 were characterised in solution by multinuclear magnetic resonance (¹H-, ¹¹B-, ¹³C-, ¹⁵N-, ²⁹Si-, ¹¹⁹Sn-NMR), using pulsed field gradients in HMBC experiments for the ¹H detected ¹⁵N- and ¹¹⁹Sn-NMR signals. The compound 5b was also studied by solid-state ¹³C, ²⁹Si and ¹¹⁹Sn MAS NMR in order to correlate liquid and solid-state NMR data with the structural evidence.     

正丁基氯化镁还原氧化石墨烯的表征

采用元素分析、红外光谱(FTIR)、X射线光电子能谱(XPS)、拉曼光谱、X射线衍射(XRD)、固体¹³C核磁共振波谱(¹³C MAS NMR)、热失重分析(TGA)、导电率测试以及原子力显微镜(AFM)等手段对正丁基氯化镁还原的氧化石墨烯进行了系统的表征. 结果表明, 正丁基氯化镁可以有效还原氧化石墨烯, 随着其用量的增加, 氧化石墨烯还原程度增加, 碳/氧摩尔比升高, 片层间距减小, 热稳定性增强, 导电率增大(可达3.6×10² S/m). 还原后部分氧化石墨烯片层发生聚集.     

A conductive polymer composite derived from polyurethane and cathodically exfoliated graphene

Composite electrodes represent an important class of electromaterials, with enhanced functional properties tailored for targeted applications. Introduction of graphene as a conductive nanofiller into the thermoplastic polyurethane (PU) provides electrodes with interesting properties. In this study, a highly conductive cathodically exfoliated graphene (CEG) of ～2–8 μm lateral size was employed to prepare CEG-PU composites. The use of this larger graphene sheet requires loading of at least 20% w/w graphene to promote contact between the sheets, hence the conductivity. The CEG-PU composite electrodes were tested to determine their electrochemical capacitance and it was found that the 40% (w/w) CEG-PU composite shows areal capacitance, energy density, and power density of 2.51 mF/cm², 1.56 μW/h/cm², and 0.48 mW/cm², respectively, at a current density of 0.2 mA/cm² and an operating voltage of 1.0 V. In summary, the CEG-PU composite electrodes have excellent conductivity, chemical/mechanical properties, and capacitive performance.     

Effect of temperature on AC conductivity of poly(butyl methacrylate)/cerium dioxide nanocomposites and applicability of different conductivity modeling studies

In this research, the effect of cerium dioxide (CeO₂) nanoparticles on electrical properties of poly(butyl methacrylate) (PBMA) has been investigated. Polymer nanocomposites reinforced with variable contents of CeO₂ nanoparticles (3, 5, 7 and 10 wt%) were fabricated by an in situ polymerization method. The formation of nanocomposites was analyzed by FTIR, XRD, SEM and TEM analysis. Also, the AC and DC conductivities of CeO₂ nanoparticles-reinforced PBMA were systematically studied with respect to different loadings of CeO₂ fillers. The FTIR, XRD and morphological studies revealed that the nanoparticles were well inserted and uniformly dispersed into the macromolecular chain of PBMA. The AC conductivity of PBMA/CeO₂ composite increases not only with the loading of nanoparticles but also with the temperature of the system. The activation energy determined from AC electrical conductivity was found to decrease with the frequency and temperature. DC conductivity of the nanocomposites was increased with the insertion of nanoparticles into PBMA. The DC conductivity of all the composites was greater than pure PBMA. The applicability of different theoretical models such as Scarisbrick, Bueche and McCullough equations was compared with the experimentally determined DC conductivity of PBMA/CeO₂ nanocomposites. These models fail to explain the conductivity of polymer composite in the entire loading of fillers. Hence, a new theoretical model is proposed in this study and it shows good agreement with the experimentally observed conductivity values.

     

Preparation and characterization of glass fiber–reinforced polyethylene terephthalate/linear low density polyethylene (GF‐PET/LLDPE) composites

Polyethylene terephthalate (PET) was melt blended with linear low density polyethylene (LLDPE) and subsequently compounded with glass fibers (GF) as reinforcements at percentages ranging from 15 to 45 wt% of LLDPE and 5 to 30 wt% of GF. Thermal, morphological, and mechanical properties of the prepared composites were investigated. It was found that compounding PET/LLDPE blends with GF would be beneficial in producing composites that are thermally stable with good mechanical properties. For example, the impact strength of the composites containing 85/15 wt% (PET/LLDPE) at relatively high loading of GF, ie, from 15 to 30 wt%, was higher than that of the GF‐reinforced neat PET. When increasing the percentage of LLDPE in the composites, the impact strength increased with increasing GF content, and this was also better than that of GF‐reinforced PET whose impact strength drastically decreased upon increasing the GF%. The improvement in mechanical properties of the composite, we suggest, should be correlated with the morphologies of the composites where the visualized interface adhesion tended to be better at higher loadings of both LLDPE and GF.     

Investigation of the proton mobility in CsH(SO4)0.76(SeO4)0.24 crystal by H NMR spectroscopy

Crystals of CsH(SO₄)_0.76(SeO₄)_0.24 formulation were studied by ¹H NMR spectroscopy. The ¹H line-shape, the T₁ and T₂ relaxation times were determined as a function of temperature. The activation energies deduced from the temperature dependence of relaxation times were compared with the activation energy issued from conductivity measurements. The results obtained are discussed and supported by the Ngai model.     

Influence of interfacial interactions on the mechanical behavior of hybrid composites of polypropylene / short glass fibers / hollow glass beads

Ternary composites of Polypropylene (PP)/Short Glass fibers (GF)/Hollow Glass Beads (HGB), with varying total and relative GF/HGB contents and using untreated and aminosilane-treated HGB compatibilized with maleated-PP, were prepared by direct injection molding of pre-extrusion compounded GF and HGB concentrates. The mechanical strength properties (tensile, flexural and Izod impact) were correlated with theoretical model predictions for hybrid composites, which identified synergistic gains over the rule of hybrid mixtures, depending upon the degree of interfacial interactions between the components of the hybrid composite. SEM analysis of cryofractured composites surfaces revealed that the presence of untreated HGB particles induces fiber-polymer interfacial decoupling under mechanical loading of the hybrid composites at much lower stress levels than in the presence of treated HGB particles. Higher storage modulus (E′) and lower mechanical damping (tan δ) from DMTA established the importance of strong polymer-hybrid reinforcement interfacial interactions in the development of lightweight/high strength PP syntactic foams.     

柔性复合织物电极Graphene/Cotton和MnO2/Graphene/Cotton的合成及在电化学电容器中的应用

通过热还原法成功地制备出了柔性复合织物电极石墨烯/棉布(graphene/cotton)。热还原条件对电极的导电性能具有较大的影响。导电柔性织物电极graphene/cotton特有的多级结构使其既有利于进一步负载膺电容材料,又有利于电子和电解质离子的传输与扩散。通过电化学沉积方法,利用导电柔性织物电极graphene/cotton进一步制备出了电极MnO₂/graphene/cotton。利用扫描电子显微镜(SEM),傅里叶变换红外(FTIR)光谱,四探针测试法等表征技术对电极的结构进行了较为详细的表征。结果表明电极MnO₂/graphene/cotton的比电容可以达到536 F·g^-1。良好的电化学性能和柔性使得此类电极在柔性储能材料应用中具有极大的应用前景。     

The addition of functionalized graphene oxide to polyetherimide to improve its thermal conductivity and mechanical properties

The thermal and electrical conductivity and mechanical properties of polyetherimide (PEI) containing either alkyl‐aminated (enGO) or phenyl‐aminated graphene (pnGO) oxides were studied. A solution casting method was used to prepare functionalized graphene oxide/PEI composites with different filler contents. The introduction of functionalized graphene oxide to the PEI matrix improved the thermal conductivity, electrical conductivity, and mechanical properties. The thermal conductivities of the enGO 3 wt%/PEI and pnGO 3 wt%/PEI composites were 0.324 W/mK and 0.329 W/mK, respectively, due to the high thermal conductivity of the graphene‐based materials and the strong interface adhesion due to the filler surface treatment between the fillers and the matrix. The electrical conductivities of the functionalized graphene oxide/PEI composites were larger than that of PEI, but the electrical conductivity values were generally low, which is consistent with the magnitude of the insulator. The strong interfacial adhesion between the fillers and the matrix led to improved mechanical properties. Copyright © 2014 John Wiley & Sons, Ltd.     

Fe_3O_4/RGO复合材料的制备及其电化学性能研究

以改进Hummers法合成的氧化石墨烯(GO)为前驱体,通过水热法结合烧结工艺制备了四氧化三铁/还原氧化石墨烯(Fe_3O_4/RGO)复合材料。利用X射线衍射(XRD)、拉曼光谱(Raman)、扫描电镜(SEM)、透射电镜(TEM)等手段对复合材料的理化性能进行表征;通过充放电测试、循环伏安(CV)和电化学阻抗谱(EIS)等技术,综合考察了材料的储锂性能及电化学性能增强机制。结果表明,在200和600 m A/g电流密度下,Fe_3O_4/RGO复合负极循环60次后的放电比容量分别保持在709和479 mAh/g,表现出良好的倍率性能;相较于纯Fe_3O_4负极,复合负极呈现出更优异的锂电性能,其电化学性能的改善得益于RGO能增强材料的电导性和结构稳定性。     

三维网状结构Ru/石墨烯/碳纳米管复合材料作为锂氧电池正极催化剂的性能

利用物理浸渍和冷冻干燥等方法制备了具有三维网状结构的Ru/石墨烯/碳纳米管复合材料, 对该材料的结构、 形貌及电化学性能进行了表征和研究. 结果表明, 当Ru含量为30%, 热处理温度为500 ℃时, 材料的催化性能最优. 将其用作锂氧电池的正极催化剂, 以50 mA/g电流密度进行首次充放电时, 放电比容量约为5800 mA·h/g, 且在放电比容量为4000 mA·h/g以内时, 其极化电压仅为0.9 V; 当以50 mA/g电流密度进行恒容(500 mA·h/g)充放电循环时, 在极化电压低于1.1 V时, 仍能稳定循环12周. 复合材料电催化机理的研究结果表明, 三维网状结构不仅提供了O₂和Li⁺的传输通道, 更增加了放电产物Li₂O₂的储存场所. 金属钌纳米粒子的负载既增加了复合材料的反应活性位点, 又促进了放电产物Li₂O₂的分解.     

Synthesis and electrical properties of novel supramolecular octa-phthalocyaninato-dicobalt(II)-hexazinc(II) and dicobalt(II)-dimeric-phthalocyanine with six ferrocenylimin pendant groups

In this study supramolecular octakis phthalocyaninato-diCo(II)hexakis-Zn(II) has been synthesized in two steps. Starting with tetracyanodibenzo(1,4,7,10-tetrathia-(12-crown)) (1) and 4-nitro-1,2-dicyanobenzene (2), nitro-substituted dimeric phthalocyanine (3) was synthesized. Compound 3 reacted with unsymmetric Zn(II) phthalocyanine (4) to furnish a supramolecular assemble of a Co(II) dimer with six Zn(II) phthalocyanines through azo bridges (5). Co(II) dimeric phthalocyanine with six ferrocenyl groups (7) was obtained by the condensation of 6 with ferrocenylaldehyde. Compounds 3, 5, 6 and 7 were characterized by elemental analysis, ICP-MS, IR, UV–Vis and ¹H NMR spectroscopy. The electronic properties of a thin film of the compounds were investigated by impedance spectroscopy and d.c. conductivity measurements as a function of temperature. The a.c. conductivity is found to vary with frequency, ω, as ω^s with index s  1, suggesting a hopping conduction mechanism for 3 and 6. Whereas a frequency independent conductivity was observed for 5. It was found that reducing the nitro group to amines and azo coupling by the asymmetric nitro groups increases the electrical conductivity. The higher conductivity of 5 can be attributed to the increase in the mobility of charge carriers due to overlap of the π electron systems along the stacking direction of the molecules.     

石墨烯包覆天然球形石墨作为锂离子电池的负极材料，是否需要乙炔黑导电剂？

我们通过包覆炭化的方法制备得到了石墨烯包覆的天然球形石墨(G/SG)材料,并使用扫描电子显微镜、X射线衍射仪以及多种电化学测试手段考察了不同石墨烯含量的复合材料的形貌结构及电化学性能。我们发现,在不添加乙炔黑(AB)的情况下,G/SG复合材料表现出较高的首次库伦效率,很好的循环稳定性和高倍率性能。当石墨烯包覆量为1%时,材料50次循环后的可逆容量可与添加10%AB的天然石墨电极(SG)等同;当石墨烯包覆量为2.5%时,材料的比容量完全高于添加10%AB的石墨电极。材料电化学性能的改善归因于石墨烯的包覆。一方面,石墨烯的柔软可变性可以保证天然石墨颗粒在充放电过程中的结构完整性,从而有效改善材料的循环稳定性;另一方面,石墨烯的存在提高了电极的导电性,促进更好导电网络的形成。因此,石墨烯包覆天然球形石墨材料中,石墨烯不仅是活性物质,也发挥导电剂的作用。当添加5%的乙炔黑时,在50 mA·g^-1电流循环50次后,5%G/SG电极的可逆容量从381.1 mAh·g^-1提高到404.5 mAh·g^-1,在1 A·g^-1电流时可逆容量从82.5 mAh·g^-1提高到101.9 mAh·g^-1,这表明G/SG电极仍然需要乙炔黑导电剂。乙炔黑颗粒填充在复合材料的空隙中,通过点接触的形式连接到G/SG颗粒,与石墨烯协同作用形成了更加有效的导电网络。尽管石墨烯包覆和乙炔黑添加对天然石墨电极具有积极的影响,例如增加了天然石墨电极的导电性和储锂性能(包括可逆容量,倍率性能和循环性能),但随着石墨烯或乙炔黑的增加,电极密度通常会降低。因此,在实际应用中应考虑石墨负极材料的质量和体积容量的平衡。这些结果对天然石墨的进一步商业应用具有重要意义。我们的工作为天然石墨电极在锂电池中的电化学行为提供了一种新的认识,并且有助于制备更高性能的负极材料。