Study of Polypyrrole/Graphene Oxide Nanocomposite Structural and Morphological Changes Including Porosity

Polypyrrole/graphene oxide (PPy/GO) nanocomposite films were electrochemically synthesized to study their structural features. For this purpose, pyrrole monomer was exposed to oxidation in an aqueous dilute solution containing definite amounts of GO and a dopant electrolyte. Potentiostatic electropolymerization was carried out and the current-time curves were obtained for each electrodeposition test. Accordingly, a number of appropriate characterization analyses such as mercury porosimetry, TGA, SEM, XRD, Raman and FTIR spectroscopies were performed in order to investigate the composition and structure of the films. In this regard, factors such as incorporation of GO in the polymer matrix, porous layer structure and the thickness of the films were determined. The results showed that GO concentration could influence on both film thickness and its porous structure. Also, it was observed that the main factor controlling the film thickness and morphology is the potential applied.     

Morphological and Structural Studies of sPS/aPS Blends

Inrecentyears,thenewsedricrystallinepolymersyndiotacticp0lystyrene(sPS)hasat-ITactedmuchattentionduetoitsg0odchendcalresistanceandenhancedmechanicalperformanceatelevatedtemPeratUre.'H0wever,itexhibitshighbrittlenessandpoorimPact-resistanceandtCar-resistance.2Therefore,itisnecessarytomodifyitwithtougheningpolyIners.AsimPlemeth0dto0verc0methedriscibilityofatwo-phaseblendofsPSandatougheningpolymristotwrovetheinterfacialaffmity,wheretheadditionofablockcoP0lymerisconsideredtobemosteffective.3…     

ZnO-SnO2纳米复合氧化物光催化剂催化降解对硝基苯胺

 采用共沉淀法合成了n(Zn)/n(Sn)=2的ZnO-SnO2纳米复合氧化物光催化剂,并采用X射线衍射(XRD)、紫外-可见(UV-Vis)漫反射吸收光谱、透射电子显微镜(TEM)和N2物理吸附等方法对在500～1300 ℃焙烧不同时间制得的ZnO-SnO2纳米复合氧化物的物相组成、光吸收性能、晶粒尺寸、颗粒大小、比表面积和孔体积进行了表征. 以对硝基苯胺为模型化合物,对ZnO-SnO2复合氧化物的光催化活性进行了评价,考察了催化剂焙烧温度和焙烧时间对其催化活性的影响. 结果表明,在700 ℃焙烧2 h制得的ZnO-SnO2纳米复合氧化物具有最高的光催化活性.     

ITO和ZnO基底对电化学沉积氧化亚铜薄膜的形貌、结构的影响及作用机制

采用电化学恒电位沉积方法在ITO导电玻璃上和在ZnO薄膜上沉积氧化亚铜(Cu₂O),并通过X射线衍射(XRD)和扫描电镜(SEM)对晶体的微观结构和表面形貌进行了分析.在ZnO基底上沉积得到了纳米级的Cu₂O粒子并且具有明显择优取向,而在ITO导电玻璃上仅得到粒径为2—5μm的Cu₂O粒子,没有明显的择优取向.对薄膜的生长机理进行了讨论.     

纳米复合膜在膜分离领域的研究进展

基于纳米材料的独特性质,将其引入高分子膜所制得的纳米复合滤膜有望解决目前制约膜技术发展的“上限平衡”问题。 本文综述了碳纳米管、石墨烯、SiO2、TiO2、分子筛、ZrO2以及纳米银颗粒等纳米复合膜在膜分离领域的研究进展。 这些纳米材料对于提高复合膜的机械稳定性、亲水性、选择性、渗透性及抗污染能力等有显著的效果。 此外,对纳米复合膜的发展与应用做了展望,也对其研究中存在的问题和解决方法进行了阐述。     

多次交替浸渍法构筑簇状ZnO的PAN复合纳米纤维膜及其光催化性能

以聚丙烯腈(PAN)与氯化锌(ZnCl2)作为前驱物,采用静电纺丝工艺制备PAN/ZnCl_2复合纳米纤维膜,分别采用多次冷热交替浸渍法和单次冷热静置浸渍法得到簇状PAN/ZnO-1和PAN/ZnO-2复合纳米纤维膜。利用扫描电镜(SEM)、傅里叶红外光谱(FT-IR)、X射线衍射(XRD)、X射线能量色散光谱(XPS)和热重分析仪(TG)对复合纳米纤维膜的表面形貌和微结构进行了表征,并以亚甲基蓝(MB)为污染物模型,评价其光催化降解性能。结果表明:经冷热交替浸渍后,纳米ZnO粒子均匀地附着在PAN纤维表面,尤其在PAN/ZnO-1复合纳米纤维膜表面还出现了花状ZnO粒子;相比单次冷热静置浸渍法处理的PAN/ZnO-2复合纳米纤维膜,经多次冷热交替浸渍的PAN/ZnO-1复合纳米纤维膜循环使用3次后对MB的降解率仍可达到90%以上,具有更好的光催化活性和循环使用性能。同时,MB溶液的初始质量浓度、催化剂用量和染料溶液的pH等因素对样品的的光催化降解率有一定影响。     

Preparation of Sol-Gel Nano-Composites Containing Copper Oxide and Their Gas Sensing Properties

Sol-gel derived composite materials were prepared with nano-sized copper particles in silica matrix. Nano-sized oxide coatings were grown on the nano-particles of copper by subjecting the composites to a controlled oxidation treatment at different temperatures. The current response of samples with oxide layers of different thickness were studied at fixed temperatures in the range 350–450°C in the presence of different concentrations of CO and NO₂. The nano-composites were sensitive to both the gases. The operating temperature and the oxide thickness were found to have significant effect on the sensing properties.     

FTIR Spectroscopic Study of Crystallization of Uniaxial Drawn Syndiotactic Polystyrene/Carbon Nanotube Nanocomposite Films

The crystallization of uniaxial hot drawn syndiotactic polystyrene/multi-walled carbon nanotube (sPS/MWCNT) nanocomposite films was studied by FTIR spectroscopy. The effects of MWCNT content, draw ratio and drawing temperature on the sPS crystallinity were investigated. The sPS/MWCMT nanocomposite films show reduced crystallinities with the increase of MWCNT content. In addition, with the increase of draw ratio, both the pure sPS and the sPS/MWCNT nanocomposite drawn films exhibit increased crystallinity. The effect of drawing temperature on the sPS crystallization is complex. In a temperature range of 100―135 ℃, the crystallinity decreases with drawing temperature, whereas it increases at 140 ℃ for both pure sPS and its nanocomposite films.     

从氧化锌矿制备高纯超细ZnO粉体

超细ＺｎＯ具有表面效应、体积效应、久保效应以及优良的光活性、电活性、烧结活性和催化活性 ,可用来制造气体传感器、荧光体、紫外线遮蔽材料、变阻器、图像记录材料、压电材料、压敏电阻、高效催化剂、磁性材料、陶瓷材料、化妆品及医药材料。在橡胶工业、染料油墨等领域也有应用前景[1～ 5] 。目前 ,国内外对制备超细ＺｎＯ粉体的研究文章较多 ,但以氧化锌矿为原料直接研制的文章还很少。湿化学法是近二十年来超细ＺｎＯ产品应用开发的主要活跃点之一 ,直接沉淀法是制备超细ＺｎＯ的一种重要湿化学方法 ,它是在含有一种或多种粒子的可溶…     

Carboxyl-functionalized Nanocellulose Reinforced Nanocomposite Proton Exchange Membrane

Nanocellulose(NCC) was prepared through the acid hydrolysis of microcellulose(MCC) and was reacted with maleic anliydride to obtain carboxyl-functionized nanocellulose(MA-NCCs). The presence of .OH and .SO3H on the surface of rod-like MA-NCC was confirmed by Fourier transfonn infrared spectrometry(FTIR). Sulfonated poly(aryl ether ether ketone ketone)(Ph-SPEEKK) was synthesized with bis(4-fluorophenyl-methanone) and 2-phenylhydroquinone as monomer. MA-NCC/Ph-SPEEKK nanocomposite membranes with different MA-NCCs content were prepared, and their properties were characterized. Compared with Ph-SPEEKK, MA-NCC/Ph-SPEEKK nanocomposite membrane showed better mechanical and thermal properties and higher proton conductivity. The proton conductivity of the composite membrane with 4%(mass fraction) MA-NCCs under 80℃ was 0.095 S/cm. And its tensile strength reached 30.3 MPa, which was 21.2% higher than that of Ph-SPEEKK pure polymer membrane.     

Gravimetric Study of Interaction of Water Vapour with Metallic Zinc

The interaction between samples of metallic zinc and water vapour was studied gravimetrically, both in the absence and in the presence of oxygen. The experimental total mass gain vs. time curves exhibited two plateaus, whose heights increased with, elevations both of relative humidity and of temperature. The amount of product retained on the surface after desorption was also determined as a function of time. The product was identified as hydrated zinc oxide. In the runs conducted without oxygen, the retained product curves displayed a time delay with respect to the total mass gain curves. In the presence of oxygen, however, there was practically only one chronogravimetric curve. This behaviour is interpreted on the basis of a common mechanism involving the formation of an intermediate precursor oxide, which is more readily formed in the presence of oxygen than in its absence. A set of mathematical equations was derived, from which the rate constants for both processes were obtained. The second step was ascribed to a further weak adsorption of water. This revised version was published online in July 2006 with corrections to the Cover Date.     

Wetting Properties of Barium Sodium Niobate Filled Polystyrene Nanocomposite

Nano crystalline powders of Barium Sodium Niobate (BNN) with the composition (Ba₃ Na₄Nb₁₀ O₃₀) have been prepared by conventional ceramic technique. XRD and SEM studies revealed that its particle size is in the nanometer range. Composites were prepared by mixing powders of BNN with polystyrene at different volume fractions of the material. Melt mixing technique was carried out in brabender plasticoder at a rotor speed of 60 rpm for composite preparation. Surface energy characteristics of the composites are measured using contact angle measurements of the composites with water and methlene iodide. The solid surface free energy is calculated from harmonic mean equations. The results are quantitatively analyzed with Girifalco-Good empirical model and provide unique insight into its properties. Various wettability parameters such as total solid surface free energy, work of adhesion, interfacial free energy and spreading coefficient are analyzed. The different parameters are calculated from the harmonic mean equation. The work of adhesion and interfacial free energy, spreading coefficient, and Girifalco-Good's interaction parameter had changed with composition. The surface properties can be controlled for a given polymer-surface pair by controlling the chemical structure, composition etc.     

从Mn_3O_4前驱体到MnO_2纳米结构的形貌和结构变化(英文)

锰氧化物是一类重要的且具有广泛应用背景的材料,控制合成不同形貌和组成的锰氧化物纳米结构将有助于拓宽其应用领域.本文报道了以Mn3O4为前驱体,通过水热法控制合成MnO2纳米结构的方法.用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)等手段对产物进行表征.在硫酸体系中,当反应温度为80和180℃时,所得产物分别为γ-MnO2海胆结构和β-MnO2单晶纳米棒.此外,MnOOH纳米线可以在稀酸溶液中合成.考察了反应温度、溶液酸度、反应时间对产物结构的影响,并提出了基于γ-MnO2为中间产物的反应机理.实验结果表明,水热体系促进了产物的各向异性生长并最终形成不同形貌和结构的锰氧化物.     

碱式碳酸锌非等温热分解动力学研究

采用TG-DTA曲线分析研究了碱式碳酸锌在氮气气氛中的热分解反应动力学,利用Doyle-Ozawa法和Kissinger法对碱式碳酸锌非等温热分解动力学数据进行了分析,同时运用Satava-Sestak法研究了碱式碳酸锌的热分解机理.结果表明,碱式碳酸锌的热分解反应服从随机成核和随后生长机理.     

Synthetic and Structural Studies of Ethyl Zinc β-Amidoenoates and β-Ketoiminates

A set of heteroleptic ethyl zinc β-amidoenoates (1, 2) and β-ketoiminates (3) of the form [LZnEt]₂ with varying steric bulk have been synthesised via the reaction of diethylzinc with β-aminoenoate ligands HL¹ and HL² and β-ketoimine HL³. These complexes have been characterised via ¹H and ¹³C NMR, mass spectrometry and single-crystal X-ray diffraction, which unambiguously determined all three structures as dimeric species in the solid state. We observe the unusual dimerisation of 1 and 2 through coordination of the central zinc atom to the methine carbon of the second monomer, which gives these complexes high reactivity. The thermal properties of complex 3 are explored via thermal gravimetric analysis (TGA), to investigate their potential as single-source precursors to zinc oxide, which shows that 3 has a significantly lower decomposition temperature as compared to its bis-ligated counterpart [Zn(L³)₂], which gives 3 promise as a single-source precursor to zinc oxide.